Sorry everyone, but somehow my Yahoo e-mail account was violated.  Ignore the
obviously fake e-mail message sent about London.  I have contacted Yahoo and
have changed my password.  As this has not happened to me before, let me know if
there is anything else that you advise me to do.

Thanks

Steve

Steve Cannistra
e-mail: sc02492@...
webpage: http://www.starrywonders.com

<I need to try PixInsight's thing, I finally found it somewhere, but they
don't have that free version on their website anymore.>

Yes they do - but the version that you are referring to HAS been withdrawn
because it just no longer represents the true power that PI brings to the
world of astroimage processing.

What you get now is the FULL program, unrestricted, apart from a 30-day
trial limit.

Providing you are willing to put the effort into 'getting to know' the
program during that 30-day trial, I think you will be happily amazed at the
power it can offer (look at the results on APOD recently, for example).

And, apart from just getting to know the program, drop by their discussion
forum as well. Meet the guys who actually WRITE the code, and not just them,
but a whole load of other enthusiasts, many of whose names might be familiar
to Forum visitors here on Yahoo.

I know that PS has been a respectable performer - and has been well
supported by many of the top imagers, but PI adds another level of power to
your image processing arsenal.

Cheers,
Niall Saunders
Clinterty Observatories
Aberdeen, SCOTLAND

Hi Steve,

I don't know what your email said, but I received an email recently from an
astronomer friend, saying that he was in London and had been robbed and to send
money.  My first reaction was that someone had stolen his mailing list.  (He's
on Yahoo too.)  But in retrospect, it's possible that a virus on any one of our
computers could be sending email out under other people's names.  To make a
case, if you and my friend both send me email, and if my computer is infected,
then it would send out email under your names.  And no one would have had to
steal a mailing list from Yahoo to do this.  (No, my computer didn't do it!)

I mention this because it's an interesting coincidence that my friend was an
astronomer too.  It might mean that some common astronomer friend, perhaps
someone reading this list, was the culprit.

Hilary

--- In ccd-newastro@yahoogroups.com, Steve Cannistra <sc02492@...> wrote:
>
> Sorry everyone, but somehow my Yahoo e-mail account was violated.  Ignore the
obviously fake e-mail message sent about London.  I have contacted Yahoo and
have changed my password.  As this has not happened to me before, let me know if
there is anything else that you advise me to do.
>
> Thanks
>
> Steve
>
> Steve Cannistra
> e-mail: sc02492@...
> webpage: http://www.starrywonders.com
>

Hi all,

This is becoming common. I have so far received three from different people
all astro-related (Two Yahoo and one GMail) and all were exactly the same
scam. It is the online email account that is hacked.

Once the online account has been accessed by the scammer, they have access
to every email you sent and received from that account.

Then its a simple matter for them to target your astro-friends and
acquaintences with the bogus email.

If you cannot get into your account any more (they probably changed the
password once they got in), then notify the security teams of the online
account provider and have the account suspended in order to stop the flow of
information between your well-meaning friends and the scammers..

Believe it or not, people have sent money to these people thinking they were
helping a friend....

Regards
Eddie Trimarchi
http://astroshed.com


On Wed, Nov 18, 2009 at 7:42 AM, hilary15xx <hilaryyahoo3@...>wrote:

> Hi Steve,
>
> I don't know what your email said, but I received an email recently from an
> astronomer friend, saying that he was in London and had been robbed and to
> send money.  My first reaction was that someone had stolen his mailing list.
>  (He's on Yahoo too.)  But in retrospect, it's possible that a virus on any
> one of our computers could be sending email out under other people's names.
>  To make a case, if you and my friend both send me email, and if my computer
> is infected, then it would send out email under your names.  And no one
> would have had to steal a mailing list from Yahoo to do this.  (No, my
> computer didn't do it!)
>
> I mention this because it's an interesting coincidence that my friend was
> an astronomer too.  It might mean that some common astronomer friend,
> perhaps someone reading this list, was the culprit.
>
> Hilary
>
> --- In ccd-newastro@yahoogroups.com, Steve Cannistra <sc02492@...> wrote:
> >
> > Sorry everyone, but somehow my Yahoo e-mail account was violated.  Ignore
> the obviously fake e-mail message sent about London.  I have contacted Yahoo
> and have changed my password.  As this has not happened to me before, let me
> know if there is anything else that you advise me to do.
> >
> > Thanks
> >
> > Steve
> >
> > Steve Cannistra
> > e-mail: sc02492@...
> > webpage: http://www.starrywonders.com
> >
>
>
>
>
> ------------------------------------
>
>
>
>
>


--
Regards,

Eddie Trimarchi
~~~~~~~~~~~
http://astroshed.com


[Non-text portions of this message have been removed]

Hi Tom,

If you have multiple distinct peaks in your histogram, your background sky is
not neutralized. Those peaks represent blue, green, and red. The fact that
they're not one peak means that the background sky is stronger in one of the
primary colors and weaker in the others. Using the Levels' center eyedropper
sets the grey point. If you're doing it correctly on an empty area of the sky
and using the eyedropper with a setting that averages surrounding pixels, that
should neutralize the sky background and restore your object color more or less
also.

I wouldn't consider it cheating or a trick. It's a legitimate way to remove an
"unnatural" color cast to the sky that could be caused by light pollution, sky
glow, an LPS filter, or a one-shot color camera.

I perform this step all the time when imaging with my DSLR.

Best,
Danny
http://www.californiastars.net/


--- In ccd-newastro@yahoogroups.com, "tegwilym" <tegwilym@...> wrote:
>
> Lately I've been doing this:
> I'll see a few spikes of data in my histogram, so do get it all into one
spike, I'll open levels, then with the center "picker eyedrop" thing, I'll click
on what appears to be empty sky.  The image then seems to even out pretty good.
>
> I'm still a novice at this, and I'm not out for completely accurate images,
just something that looks kind of pretty.  Is this a lousy short cut kind of
trick?
>
> I always use the GradientXterminator that thing is a lifesaver for my Seattle
skies.
> I need to try PixInsight's thing, I finally found it somewhere, but they don't
have that free version on their website anymore.
>
> I went to the Advanced Imaging Conference a few weeks ago, and have been
trying some new things.  Here is my latest tinkering.
> http://eas-astroblog.blogspot.com/2009/11/trying-new-processing-tricks.html
>
> Tom
>
>
>
> --- In ccd-newastro@yahoogroups.com, Wodaski - Yahoo <yahoo@> wrote:
> >
> > If you are trailing off to the right that weakly, then the _best_ answer is
longer exposures. <g>
> >
> > There isn't a definitive place for the white point; you only need to set it
when your exposures are too short. It's a judgment call; you will need to
experiment to find the ideal place, but anywhere where the line is discontinuous
(dotted, dashed, weakening) is as good a place as any to start with. The only
time to worry is if you find that your stars are too hard-edged because you've
placed it too low.
> >
> > Even when you have a short exposure, you can ignore the white point entirely
and simply keep pushing up the dim zone with the standard curve. You may find it
easier to settle on a white point after one or more applications of the curve.
Because the exposure is short, you don't have a full complement of dynamic range
anyway, so you have a limited (partial) range in which to boost the dim zone.
> >
> > Ron W
> >
> > On Nov 16, 2009, at 7:06 PM, Robert wrote:
> >
> > > After my first year of imaging, I've gone back to Ron's Zone System book
and have a question about setting the white point in the levels window of
Photoshop.  I know to move the black point to just before the distribution
begins, but I'm never quite sure about setting the white point.  Often there
seems to be a hair-thin distribution extension that goes a long way off to the
right.  Is it best to stay to the right of that, or simply to stay to the right
of the beginning of the tailing off point?
> > >
> > > Thanks,
> > > Bob Hertel
> > >
> > >
> > >
> > > ------------------------------------
> > >
> > >
> > >
> > >
> >
>

Eddie Trimarchi wrote:
> This is becoming common. I have so far received three from different people
> all astro-related (Two Yahoo and one GMail) and all were exactly the same
> scam. It is the online email account that is hacked.
>
> Once the online account has been accessed by the scammer, they have access
> to every email you sent and received from that account.
>
> Then its a simple matter for them to target your astro-friends and
> acquaintences with the bogus email.
>
> If you cannot get into your account any more (they probably changed the
> password once they got in), then notify the security teams of the online
> account provider and have the account suspended in order to stop the flow of
> information between your well-meaning friends and the scammers..
>
> Believe it or not, people have sent money to these people thinking they were
> helping a friend....
>
> Regards
> Eddie Trimarchi
> http://astroshed.com

To add to Eddie's comments - In around the October timeframe gmail,
hotmail and yahoo were all compromised. Both email addresses and their
relevant passwords were widely available for download (at least 30k
addresses so a small but significant number).

Unfortunately many people use the same password for many different
purposes - so the scammers naturally try various other services that
they can identify with that person and try the same password. A close
friend had her paypal account hacked recently and this is one potential
way that they did it.

This is a warning to all of us to make sure that we do not have a single
password, equating to a single point of failure. If you have or have had
a hotmail or gmail account, and have used the same password elsewhere
then you absolutely must change to new passwords everywhere.

I recommend we all change our yahoo and/or gmail password in any event.
Unfortunately the service providers have not done a good job at
advertising this security breach or recommending people change their
password - as far as I am aware, even for the people who's accounts were
on the list!

http://www.theregister.co.uk/2009/10/06/gmail_webmail_phish/
http://www.theinquirer.net/inquirer/news/1557535/hotmail-suffers-massive-theft
http://www.theregister.co.uk/2009/10/07/scam_spam_spike/

Cheers, Paul.
--
http://www.beskeen.com

Ok, sounds good. Thanks for the advice and reassurance.  I actually just
discovered that recently on one of the forums where someone showed that on a
processing web page.  Seems to really help a lot with getting colors more
accurate.
So much to learn!

Tom


--- In ccd-newastro@yahoogroups.com, "dannysperry" <danny@...> wrote:
>
> Hi Tom,
>
> If you have multiple distinct peaks in your histogram, your background sky is
not neutralized. Those peaks represent blue, green, and red. The fact that
they're not one peak means that the background sky is stronger in one of the
primary colors and weaker in the others. Using the Levels' center eyedropper
sets the grey point. If you're doing it correctly on an empty area of the sky
and using the eyedropper with a setting that averages surrounding pixels, that
should neutralize the sky background and restore your object color more or less
also.
>
> I wouldn't consider it cheating or a trick. It's a legitimate way to remove an
"unnatural" color cast to the sky that could be caused by light pollution, sky
glow, an LPS filter, or a one-shot color camera.
>
> I perform this step all the time when imaging with my DSLR.
>
> Best,
> Danny
> http://www.californiastars.net/
>
>
> --- In ccd-newastro@yahoogroups.com, "tegwilym" <tegwilym@> wrote:
> >
> > Lately I've been doing this:
> > I'll see a few spikes of data in my histogram, so do get it all into one
spike, I'll open levels, then with the center "picker eyedrop" thing, I'll click
on what appears to be empty sky.  The image then seems to even out pretty good.
> >
> > I'm still a novice at this, and I'm not out for completely accurate images,
just something that looks kind of pretty.  Is this a lousy short cut kind of
trick?
> >
> > I always use the GradientXterminator that thing is a lifesaver for my
Seattle skies.
> > I need to try PixInsight's thing, I finally found it somewhere, but they
don't have that free version on their website anymore.
> >
> > I went to the Advanced Imaging Conference a few weeks ago, and have been
trying some new things.  Here is my latest tinkering.
> > http://eas-astroblog.blogspot.com/2009/11/trying-new-processing-tricks.html
> >
> > Tom
> >
> >
> >
> > --- In ccd-newastro@yahoogroups.com, Wodaski - Yahoo <yahoo@> wrote:
> > >
> > > If you are trailing off to the right that weakly, then the _best_ answer
is longer exposures. <g>
> > >
> > > There isn't a definitive place for the white point; you only need to set
it when your exposures are too short. It's a judgment call; you will need to
experiment to find the ideal place, but anywhere where the line is discontinuous
(dotted, dashed, weakening) is as good a place as any to start with. The only
time to worry is if you find that your stars are too hard-edged because you've
placed it too low.
> > >
> > > Even when you have a short exposure, you can ignore the white point
entirely and simply keep pushing up the dim zone with the standard curve. You
may find it easier to settle on a white point after one or more applications of
the curve. Because the exposure is short, you don't have a full complement of
dynamic range anyway, so you have a limited (partial) range in which to boost
the dim zone.
> > >
> > > Ron W
> > >
> > > On Nov 16, 2009, at 7:06 PM, Robert wrote:
> > >
> > > > After my first year of imaging, I've gone back to Ron's Zone System book
and have a question about setting the white point in the levels window of
Photoshop.  I know to move the black point to just before the distribution
begins, but I'm never quite sure about setting the white point.  Often there
seems to be a hair-thin distribution extension that goes a long way off to the
right.  Is it best to stay to the right of that, or simply to stay to the right
of the beginning of the tailing off point?
> > > >
> > > > Thanks,
> > > > Bob Hertel
> > > >
> > > >
> > > >
> > > > ------------------------------------
> > > >
> > > >
> > > >
> > > >
> > >
> >
>

I am confused by this, although it does not take much with me.

By throwing more light onto the chip, would that not also include whatever is
causing the gradient as well? By your comment I suspect this does not occur,
but am curious as to why this is.



Many thanks for educating me on this.



Jim  
----- Original Message -----
From: " Wodaski - Yahoo" <yahoo@ wodaski .com>
To: ccd-newastro@ yahoogroups .com
Sent: Tuesday, November 17, 2009 9:16:12 AM GMT -07:00 US/Canada Mountain
Subject: Re: [ccd-newastro] Re: Light Pollution Gradients

A larger aperture that has the same FOV will be throwing more light onto the
chip, so your gradients will have better S/N. That's about the only difference.
So they should clean up a little bit better.

Ron W

On Nov 17, 2009, at 8:12 AM, ancient. sull wrote:

> I have and use GradientXterminator but the real question is, will going from a
150 mm scope with a FL ~ 1200 to a 300mm scope which still has a FL of about
1200mm and has the same field of view make the problem worse or not change it at
all?
>
> Drew S
>
> --- In ccd-newastro@ yahoogroups .com, "donsinger1" <don@...> wrote:
>>
>> An example of the problem would be great:). But, in software, there are the
"usual" suspects such as Gradient Xterminator . Others, such as the
DynamicBackroundExtraction in PixInsight are amazing.
>>
>> Don
>>
>> --- In ccd-newastro@ yahoogroups .com, "ancient. sull " <ancient. sull @>
wrote:
>>>
>>> Where I image there is a city a few miles in one direction and reasonably
dark skies in the other direction. Light pollution _gradients_ are causing me
more problems than total light pollution.
>>>
>>> Am I correct that light pollution gradients are a function of field of view,
and therefore (with a given camera chip) of focal length, but not of aperture?
In other words if I have two scopes, both with a FL of 1200mm, one with twice
the aperture of the other, will they have the same light pollution gradient?
>>>
>>> Is there any disadvantage (assuming the same FL) of a larger aperture in an
area with "mild suburban" light pollution? Will the extra aperture be wasted if
I get a faster, larger aperture scope?
>>>
>>> I realize I will hit sky background sooner and may adjust subexposure length
but will the final image be better/worse/the same?
>>>
>>> Regards,
>>>
>>> Drew Sullivan
>>>
>>
>
>
>
>
> ------------------------------------
>
>
>
>



[Non-text portions of this message have been removed]

Yes, it will put more of the gradient photons on the chip. That's what I mean
when I say that the gradients will have better S/N. That is why they can be
removed more cleanly. Even for unwanted signal, cleaner (more) is better. <g>

Ron Wodaski

On Nov 18, 2009, at 4:18 PM, jfmiller7@... wrote:

>
>
> I am confused by this, although it does not take much with me.
>
> By throwing more light onto the chip, would that not also include whatever is
causing the gradient as well? By your comment I suspect this does not occur, but
am curious as to why this is.
>
>
>
> Many thanks for educating me on this.
>
>
>
> Jim
> ----- Original Message -----
> From: " Wodaski - Yahoo" <yahoo@ wodaski .com>
> To: ccd-newastro@ yahoogroups .com
> Sent: Tuesday, November 17, 2009 9:16:12 AM GMT -07:00 US/Canada Mountain
> Subject: Re: [ccd-newastro] Re: Light Pollution Gradients
>
> A larger aperture that has the same FOV will be throwing more light onto the
chip, so your gradients will have better S/N. That's about the only difference.
So they should clean up a little bit better.
>
> Ron W
>
> On Nov 17, 2009, at 8:12 AM, ancient. sull wrote:
>
>> I have and use GradientXterminator but the real question is, will going from
a 150 mm scope with a FL ~ 1200 to a 300mm scope which still has a FL of about
1200mm and has the same field of view make the problem worse or not change it at
all?
>>
>> Drew S
>>
>> --- In ccd-newastro@ yahoogroups .com, "donsinger1" <don@...> wrote:
>>>
>>> An example of the problem would be great:). But, in software, there are the
"usual" suspects such as Gradient Xterminator . Others, such as the
DynamicBackroundExtraction in PixInsight are amazing.
>>>
>>> Don
>>>
>>> --- In ccd-newastro@ yahoogroups .com, "ancient. sull " <ancient. sull @>
wrote:
>>>>
>>>> Where I image there is a city a few miles in one direction and reasonably
dark skies in the other direction. Light pollution _gradients_ are causing me
more problems than total light pollution.
>>>>
>>>> Am I correct that light pollution gradients are a function of field of
view, and therefore (with a given camera chip) of focal length, but not of
aperture? In other words if I have two scopes, both with a FL of 1200mm, one
with twice the aperture of the other, will they have the same light pollution
gradient?
>>>>
>>>> Is there any disadvantage (assuming the same FL) of a larger aperture in an
area with "mild suburban" light pollution? Will the extra aperture be wasted if
I get a faster, larger aperture scope?
>>>>
>>>> I realize I will hit sky background sooner and may adjust subexposure
length but will the final image be better/worse/the same?
>>>>
>>>> Regards,
>>>>
>>>> Drew Sullivan
>>>>
>>>
>>
>>
>>
>>
>> ------------------------------------
>>
>>
>>
>>
>
>
>
> [Non-text portions of this message have been removed]
>
>
>
> ------------------------------------
>
>
>
>

Hi Everyone,

I'm a new member here. I've been a photographer for a long time and use a DSLR,
Nikon D90. My husband and I are looking into purchasing a telescope that can be
used with a DSLR camera. I've just started looking at information on them and
I'm hoping to get some advice on which models are good. We're looking in around
a $400 price range.

I'd appreciate any advice.

Thanks!

Rebecca

if thats all you want to spend look at the orion 80mm ED

--- In ccd-newastro@yahoogroups.com, "rebeccry" <rebeccry@...> wrote:
>
> Hi Everyone,
>
> I'm a new member here. I've been a photographer for a long time and use a
DSLR, Nikon D90. My husband and I are looking into purchasing a telescope that
can be used with a DSLR camera. I've just started looking at information on them
and I'm hoping to get some advice on which models are good. We're looking in
around a $400 price range.
>
> I'd appreciate any advice.
>
> Thanks!
>
> Rebecca
>

Almost any telescope can be used with a DSLR. You'll need a "T" adapter for your
D90 and a "T" to 1.25" adapter to attach the camera to the telescope. Prime
focus imaging uses the telescope as a fixed aperture telephoto lens. Eyepiece
projection imaging uses a special eyepiece holder and one of your eyepieces to
increase the apparent focal length of the telescope. A focuser on the telescope
that has a fine enough movement to allow easy focusing is needed and it also
must be sturdy enough to keep the camera held in place with tilting relative to
the axis of the telescope.

If you are using this for terrestrial photography, that's all you'll need. If
you are looking at astrophotography, you'll be limited to imaging the moon and
bright planets. Almost all other astronomical imaging requires exposures long
enough to cause the object being imaged to produce a trail of light instead of a
point. A telescope mount with a clock drive can correct this (caused by the
Earth's rotation) but requires a very high precision set of gears (read: lots of
$$$) to move the mount at exactly the correct rate to make objects appear
motionless in the sky.

If you're interested in astrophotography, you can try the following to get some
idea of this issue.
1. Setup your camera with the longest lens you have, on a tripod facing South,
with the camera pointing around 45 degrees above the Southern horizon. Use the
fastest ASA setting of the camera. If you do this after 5am this month, the
Orion constellation makes a great test object.
2. Take a series of photos, 1,2,5,10,20,30 seconds. If you can take longer ones,
also try 60 seconds.
3. Look at the images - you'll see the effects of Earth's rotation as the
exposure time increases. You should also see how longer exposures show more
stars. Don't be surprised at how dim the images look. Astrophotos of deep space
objects (DSOs) require lots of post processing to bring out what the camera
recorded.

Phil

--- In ccd-newastro@yahoogroups.com, "rebeccry" <rebeccry@...> wrote:
>
> Hi Everyone,
>
> I'm a new member here. I've been a photographer for a long time and use a
DSLR, Nikon D90. My husband and I are looking into purchasing a telescope that
can be used with a DSLR camera. I've just started looking at information on them
and I'm hoping to get some advice on which models are good. We're looking in
around a $400 price range.
>
> I'd appreciate any advice.
>
> Thanks!
>
> Rebecca
>

I would look at this site for great deals on used and or new gear.
http://www.astromart.com/
HTH
Jim

--- On Fri, 11/20/09, phils67 <plsherman@...> wrote:


From: phils67 <plsherman@...>
Subject: [ccd-newastro] Re: Newbie with telescope questions
To: ccd-newastro@yahoogroups.com
Date: Friday, November 20, 2009, 1:46 PM


 



Almost any telescope can be used with a DSLR. You'll need a "T" adapter for your
D90 and a "T" to 1.25" adapter to attach the camera to the telescope. Prime
focus imaging uses the telescope as a fixed aperture telephoto lens. Eyepiece
projection imaging uses a special eyepiece holder and one of your eyepieces to
increase the apparent focal length of the telescope. A focuser on the telescope
that has a fine enough movement to allow easy focusing is needed and it also
must be sturdy enough to keep the camera held in place with tilting relative to
the axis of the telescope.

If you are using this for terrestrial photography, that's all you'll need. If
you are looking at astrophotography, you'll be limited to imaging the moon and
bright planets. Almost all other astronomical imaging requires exposures long
enough to cause the object being imaged to produce a trail of light instead of a
point. A telescope mount with a clock drive can correct this (caused by the
Earth's rotation) but requires a very high precision set of gears (read: lots of
$$$) to move the mount at exactly the correct rate to make objects appear
motionless in the sky.

If you're interested in astrophotography, you can try the following to get some
idea of this issue.
1. Setup your camera with the longest lens you have, on a tripod facing South,
with the camera pointing around 45 degrees above the Southern horizon. Use the
fastest ASA setting of the camera. If you do this after 5am this month, the
Orion constellation makes a great test object.
2. Take a series of photos, 1,2,5,10,20, 30 seconds. If you can take longer
ones, also try 60 seconds.
3. Look at the images - you'll see the effects of Earth's rotation as the
exposure time increases. You should also see how longer exposures show more
stars. Don't be surprised at how dim the images look. Astrophotos of deep space
objects (DSOs) require lots of post processing to bring out what the camera
recorded.

Phil

--- In ccd-newastro@ yahoogroups. com, "rebeccry" <rebeccry@.. .> wrote:
>
> Hi Everyone,
>
> I'm a new member here. I've been a photographer for a long time and use a
DSLR, Nikon D90. My husband and I are looking into purchasing a telescope that
can be used with a DSLR camera. I've just started looking at information on them
and I'm hoping to get some advice on which models are good. We're looking in
around a $400 price range.
>
> I'd appreciate any advice.
>
> Thanks!
>
> Rebecca
>








[Non-text portions of this message have been removed]

Hi Rebecca,

Regardless of which scope you get, keep in mind that you won't be able to take
long exposures without a quality, tracking mount. $400 may get you a decent
refractor but what will you put it on so it can track the sky? :)

If you just put it on a tripod, you'll be limited to taking daytime pictures of
pictures of the moon. That's about it.

Best,
Danny


--- In ccd-newastro@yahoogroups.com, "rebeccry" <rebeccry@...> wrote:
>
> Hi Everyone,
>
> I'm a new member here. I've been a photographer for a long time and use a
DSLR, Nikon D90. My husband and I are looking into purchasing a telescope that
can be used with a DSLR camera. I've just started looking at information on them
and I'm hoping to get some advice on which models are good. We're looking in
around a $400 price range.
>
> I'd appreciate any advice.
>
> Thanks!
>
> Rebecca
>

Here is my advice, for what it is worth.

Four hundred dollars wont buy you much of a telescope. A quick search on eBay
will show you hundreds, if not thousands, of "department store" telescopes which
are pretty useless and end up killing your interest with the frustration.

If you want to get into deep sky photography, you would be better off investing
in a decent lens to go with the camera and either build, or buy, a small mount
that will allow you to track the movement of stars, for short periods of time.
Anyone with even very modest skills can build a small equatorial platform in a
day or so at very little cost.

You can achieve good results with a basic DSLR and test the water in relation to
your interest in astrophotography and many beautifl shots of the night sky have
been done this way.

If you want to do visual observing, for $400, I'd invest in a decent star atlas,
(about $100), and a couple of good pairs of binoculars, (about 7 X 50's).  Good
binoculars will last a life time and can be used for lots of different
activities.

Once you've determined that you want to pursue the hobby, get a decent
equatorial mount so that you can track for longer periods of time then invest in
a small high quality refractor. You can do that for around $1000 and it'll keep
you happy for a ong time.

Good luck, you are taking your first steps on a most amazing journey

[Non-text portions of this message have been removed]

One more thing to add to this post would be to join an astro club if you have
one locally.  An average club will have a yearly membership fee of probably
less than $50 and with that you get the use of all the equipment available. Plus
the experience from other members. 
HTH
Jim

--- On Sat, 11/21/09, Rom Springall <starman00@...> wrote:


From: Rom Springall <starman00@...>
Subject: [ccd-newastro] Re:Newbie with telescope questions
To: ccd-newastro@yahoogroups.com
Date: Saturday, November 21, 2009, 4:16 PM


 



Here is my advice, for what it is worth.

Four hundred dollars wont buy you much of a telescope. A quick search on eBay
will show you hundreds, if not thousands, of "department store" telescopes which
are pretty useless and end up killing your interest with the frustration.

If you want to get into deep sky photography, you would be better off investing
in a decent lens to go with the camera and either build, or buy, a small mount
that will allow you to track the movement of stars, for short periods of time.
Anyone with even very modest skills can build a small equatorial platform in a
day or so at very little cost.

You can achieve good results with a basic DSLR and test the water in relation to
your interest in astrophotography and many beautifl shots of the night sky have
been done this way.

If you want to do visual observing, for $400, I'd invest in a decent star atlas,
(about $100), and a couple of good pairs of binoculars, (about 7 X 50's). Good
binoculars will last a life time and can be used for lots of different
activities.

Once you've determined that you want to pursue the hobby, get a decent
equatorial mount so that you can track for longer periods of time then invest in
a small high quality refractor. You can do that for around $1000 and it'll keep
you happy for a ong time.

Good luck, you are taking your first steps on a most amazing journey

[Non-text portions of this message have been removed]








[Non-text portions of this message have been removed]

Link here:

http://www.telescope.com/control/product/~category_id=mounts_and_tripods/~pcateg\
ory=accessories/~product_id=09055

On Sat, Nov 21, 2009 at 11:03 PM, Kelsey Golden <kcgolden@...> wrote:

> Actually, something tells me that this little $59 "table top" mount would
> be even better than the $115 taller mount. Lower to the ground and shorter
> legs means easier to control vibration.
>
> The key to this of course is to set the mount up on the ground and get a
> nice long shutter release cable so you can avoid going anywhere near the
> mount when taking pictures. Good solid earth is the best place to setup for
> astrophotography, not concrete.
>
> Kelsey
>
>
> On Sat, Nov 21, 2009 at 10:54 PM, Kelsey Golden <kcgolden@...>wrote:
>
>> The biggest advice I can give having been doing astrophotography for a few
>> years is to avoid setting a goal which you cannot easily achieve on the
>> budget you have set out for yourself. $400 is plenty to start out with
>> DSLR lens "extra wide field" astrophotography. It's not nearly enough to do
>> deep space photography.
>>
>> You can take some spectacular long exposure images with just a regular
>> tripod and the camera's normal lenses. If you want tracked images, get a
>> small equatorial mount with motorized star tracking and you *should* be able
>> to stay under budget.
>>
>> If you want to get into deep sky photography, the cheapest setup I would
>> recommend would be the Orion 80ED on the Atlas mount. If you polar align
>> well enough on this mount, you can get as much as a minute exposures
>> without significant star trails. However, this setup would be about $1000 to
>> $1500 on the used market (www.astromart.com).
>>
>> Just know going in that it's very hard to do deep sky work without
>> spending closer to $1000 (and that's really a low estimate) so I would start
>> with just the camera's lenses mounted on a small equatorial mount until you
>> get the hang of it and desire something more. But I will say, the pictures
>> I've seen with just this setup alone can be among the most spectacular.
>> Here's an example:
>>
>> http://z.hubpages.com/u/101012_f520.jpg
>>
>> If you want to try such photography, I think the following $115
>> "auto-tracking" eq mount would be an adequate place to start with low focal
>> length lenses:
>>
>>
>>
http://www.telescope.com/control/product/~category_id=mounts_and_tripods/~pcateg\
ory=accessories/~product_id=09011
>>
>> Just make sure you get the motorized option, which is extra.
>>
>> You'll also need a manual shutter release which you could find at any
>> camera store.
>>
>> Finally, you may want to check out www.hutech.com for information and
>> resources to modify (or have your camera modified) to be more sensitive to
>> the kinds of light that make night sky objects so beautiful. Standard
>> out-of-box DSLR cameras tend to filter out this light since it isn't useful
>> to terrestrial photography but the camera sensors are perfectly capable of a
>> much broader spectrum if their filter is replaced and hutech sells filters
>> that make your camera useful for both terrestrial and astrophotography. This
>> is something you'll almost certainly want to do regardless of whether you do
>> deep sky or simple camera/lense astrophotography.
>>
>> I hope this helps.
>>
>> Kelsey
>>
>>
>>
>>
>>
>> On Sat, Nov 21, 2009 at 4:50 PM, James Prink <astroscuba1@...>wrote:
>>
>>>
>>>
>>> One more thing to add to this post would be to join an astro club if you
>>> have one locally.  An average club will have a yearly membership fee of
>>> probably less than $50 and with that you get the use of all the equipment
>>> available. Plus the experience from other members.
>>> HTH
>>> Jim
>>>
>>> --- On Sat, 11/21/09, Rom Springall
<starman00@...<starman00%40netspace.net.au>>
>>> wrote:
>>>
>>> From: Rom Springall <starman00@...<starman00%40netspace.net.au>
>>> >
>>>
>>> Subject: [ccd-newastro] Re:Newbie with telescope questions
>>> To: ccd-newastro@yahoogroups.com <ccd-newastro%40yahoogroups.com>
>>> Date: Saturday, November 21, 2009, 4:16 PM
>>>
>>>
>>>
>>>
>>> Here is my advice, for what it is worth.
>>>
>>> Four hundred dollars wont buy you much of a telescope. A quick search on
>>> eBay will show you hundreds, if not thousands, of "department store"
>>> telescopes which are pretty useless and end up killing your interest with
>>> the frustration.
>>>
>>> If you want to get into deep sky photography, you would be better off
>>> investing in a decent lens to go with the camera and either build, or buy, a
>>> small mount that will allow you to track the movement of stars, for short
>>> periods of time. Anyone with even very modest skills can build a small
>>> equatorial platform in a day or so at very little cost.
>>>
>>> You can achieve good results with a basic DSLR and test the water in
>>> relation to your interest in astrophotography and many beautifl shots of the
>>> night sky have been done this way.
>>>
>>> If you want to do visual observing, for $400, I'd invest in a decent star
>>> atlas, (about $100), and a couple of good pairs of binoculars, (about 7 X
>>> 50's). Good binoculars will last a life time and can be used for lots of
>>> different activities.
>>>
>>> Once you've determined that you want to pursue the hobby, get a decent
>>> equatorial mount so that you can track for longer periods of time then
>>> invest in a small high quality refractor. You can do that for around $1000
>>> and it'll keep you happy for a ong time.
>>>
>>> Good luck, you are taking your first steps on a most amazing journey
>>>
>>> [Non-text portions of this message have been removed]
>>>
>>> [Non-text portions of this message have been removed]
>>>
>>>
>>>
>>
>>
>


[Non-text portions of this message have been removed]

Now I understand.

thanks,



Jim
----- Original Message -----
From: " Wodaski - Yahoo" <yahoo@ wodaski .com>
To: ccd-newastro@ yahoogroups .com
Sent: Wednesday, November 18, 2009 4:28:37 PM GMT -07:00 US/Canada Mountain
Subject: Re: [ccd-newastro] Re: Light Pollution Gradients

 




Yes, it will put more of the gradient photons on the chip. That's what I mean
when I say that the gradients will have better S/N. That is why they can be
removed more cleanly. Even for unwanted signal, cleaner (more) is better. <g>

Ron Wodaski

On Nov 18, 2009, at 4:18 PM, jfmiller7@... wrote:

>
>
> I am confused by this, although it does not take much with me.
>
> By throwing more light onto the chip, would that not also include whatever is
causing the gradient as well? By your comment I suspect this does not occur, but
am curious as to why this is.
>
>
>
> Many thanks for educating me on this.
>
>
>
> Jim
> ----- Original Message -----
> From: " Wodaski - Yahoo" <yahoo@ wodaski .com>
> To: ccd-newastro@ yahoogroups .com
> Sent: Tuesday, November 17, 2009 9:16:12 AM GMT -07:00 US/Canada Mountain
> Subject: Re: [ccd-newastro] Re: Light Pollution Gradients
>
> A larger aperture that has the same FOV will be throwing more light onto the
chip, so your gradients will have better S/N. That's about the only difference.
So they should clean up a little bit better.
>
> Ron W
>
> On Nov 17, 2009, at 8:12 AM, ancient. sull wrote:
>
>> I have and use GradientXterminator but the real question is, will going from
a 150 mm scope with a FL ~ 1200 to a 300mm scope which still has a FL of about
1200mm and has the same field of view make the problem worse or not change it at
all?
>>
>> Drew S
>>
>> --- In ccd-newastro@ yahoogroups .com, "donsinger1" <don@...> wrote:
>>>
>>> An example of the problem would be great:). But, in software, there are the
"usual" suspects such as Gradient Xterminator . Others, such as the
DynamicBackroundExtraction in PixInsight are amazing.
>>>
>>> Don
>>>
>>> --- In ccd-newastro@ yahoogroups .com, "ancient. sull " <ancient. sull @>
wrote:
>>>>
>>>> Where I image there is a city a few miles in one direction and reasonably
dark skies in the other direction. Light pollution _gradients_ are causing me
more problems than total light pollution.
>>>>
>>>> Am I correct that light pollution gradients are a function of field of
view, and therefore (with a given camera chip) of focal length, but not of
aperture? In other words if I have two scopes, both with a FL of 1200mm, one
with twice the aperture of the other, will they have the same light pollution
gradient?
>>>>
>>>> Is there any disadvantage (assuming the same FL) of a larger aperture in an
area with "mild suburban" light pollution? Will the extra aperture be wasted if
I get a faster, larger aperture scope?
>>>>
>>>> I realize I will hit sky background sooner and may adjust subexposure
length but will the final image be better/worse/the same?
>>>>
>>>> Regards,
>>>>
>>>> Drew Sullivan
>>>>
>>>
>>
>>
>>
>>
>> ------------------------------------
>>
>>
>>
>>
>
>
>
> [Non-text portions of this message have been removed]
>
>
>
> ------------------------------------
>
>
>
>


__ ._,_. __ _

Reply to sender | Reply to group Messages in this topic ( 7 )
Recent Activity:

     • New Members 1


Visit Your Group Start a New Topic

MARKETPLACE

Mom Power: Discover the community of moms doing more for their families, for the
world and for each other
Yahoo! Groups
Switch to: Text-Only , Daily Digest • Unsubscribe • Terms of Use


.

__ ,_._, __ _

[Non-text portions of this message have been removed]

Actually, something tells me that this little $59 "table top" mount would be
even better than the $115 taller mount. Lower to the ground and shorter legs
means easier to control vibration.

The key to this of course is to set the mount up on the ground and get a
nice long shutter release cable so you can avoid going anywhere near the
mount when taking pictures. Good solid earth is the best place to setup for
astrophotography, not concrete.

Kelsey

On Sat, Nov 21, 2009 at 10:54 PM, Kelsey Golden <kcgolden@...> wrote:

> The biggest advice I can give having been doing astrophotography for a few
> years is to avoid setting a goal which you cannot easily achieve on the
> budget you have set out for yourself. $400 is plenty to start out with
> DSLR lens "extra wide field" astrophotography. It's not nearly enough to do
> deep space photography.
>
> You can take some spectacular long exposure images with just a regular
> tripod and the camera's normal lenses. If you want tracked images, get a
> small equatorial mount with motorized star tracking and you *should* be able
> to stay under budget.
>
> If you want to get into deep sky photography, the cheapest setup I would
> recommend would be the Orion 80ED on the Atlas mount. If you polar align
> well enough on this mount, you can get as much as a minute exposures
> without significant star trails. However, this setup would be about $1000 to
> $1500 on the used market (www.astromart.com).
>
> Just know going in that it's very hard to do deep sky work without spending
> closer to $1000 (and that's really a low estimate) so I would start with
> just the camera's lenses mounted on a small equatorial mount until you get
> the hang of it and desire something more. But I will say, the pictures I've
> seen with just this setup alone can be among the most spectacular. Here's an
> example:
>
> http://z.hubpages.com/u/101012_f520.jpg
>
> If you want to try such photography, I think the following $115
> "auto-tracking" eq mount would be an adequate place to start with low focal
> length lenses:
>
>
>
http://www.telescope.com/control/product/~category_id=mounts_and_tripods/~pcateg\
ory=accessories/~product_id=09011
>
> Just make sure you get the motorized option, which is extra.
>
> You'll also need a manual shutter release which you could find at any
> camera store.
>
> Finally, you may want to check out www.hutech.com for information and
> resources to modify (or have your camera modified) to be more sensitive to
> the kinds of light that make night sky objects so beautiful. Standard
> out-of-box DSLR cameras tend to filter out this light since it isn't useful
> to terrestrial photography but the camera sensors are perfectly capable of a
> much broader spectrum if their filter is replaced and hutech sells filters
> that make your camera useful for both terrestrial and astrophotography. This
> is something you'll almost certainly want to do regardless of whether you do
> deep sky or simple camera/lense astrophotography.
>
> I hope this helps.
>
> Kelsey
>
>
>
>
>
> On Sat, Nov 21, 2009 at 4:50 PM, James Prink <astroscuba1@...>wrote:
>
>>
>>
>> One more thing to add to this post would be to join an astro club if you
>> have one locally.  An average club will have a yearly membership fee of
>> probably less than $50 and with that you get the use of all the equipment
>> available. Plus the experience from other members.
>> HTH
>> Jim
>>
>> --- On Sat, 11/21/09, Rom Springall
<starman00@...<starman00%40netspace.net.au>>
>> wrote:
>>
>> From: Rom Springall <starman00@...<starman00%40netspace.net.au>
>> >
>>
>> Subject: [ccd-newastro] Re:Newbie with telescope questions
>> To: ccd-newastro@yahoogroups.com <ccd-newastro%40yahoogroups.com>
>> Date: Saturday, November 21, 2009, 4:16 PM
>>
>>
>>
>>
>> Here is my advice, for what it is worth.
>>
>> Four hundred dollars wont buy you much of a telescope. A quick search on
>> eBay will show you hundreds, if not thousands, of "department store"
>> telescopes which are pretty useless and end up killing your interest with
>> the frustration.
>>
>> If you want to get into deep sky photography, you would be better off
>> investing in a decent lens to go with the camera and either build, or buy, a
>> small mount that will allow you to track the movement of stars, for short
>> periods of time. Anyone with even very modest skills can build a small
>> equatorial platform in a day or so at very little cost.
>>
>> You can achieve good results with a basic DSLR and test the water in
>> relation to your interest in astrophotography and many beautifl shots of the
>> night sky have been done this way.
>>
>> If you want to do visual observing, for $400, I'd invest in a decent star
>> atlas, (about $100), and a couple of good pairs of binoculars, (about 7 X
>> 50's). Good binoculars will last a life time and can be used for lots of
>> different activities.
>>
>> Once you've determined that you want to pursue the hobby, get a decent
>> equatorial mount so that you can track for longer periods of time then
>> invest in a small high quality refractor. You can do that for around $1000
>> and it'll keep you happy for a ong time.
>>
>> Good luck, you are taking your first steps on a most amazing journey
>>
>> [Non-text portions of this message have been removed]
>>
>> [Non-text portions of this message have been removed]
>>
>>
>>
>
>


[Non-text portions of this message have been removed]

The biggest advice I can give having been doing astrophotography for a few
years is to avoid setting a goal which you cannot easily achieve on the
budget you have set out for yourself. $400 is plenty to start out with
DSLR lens "extra wide field" astrophotography. It's not nearly enough to do
deep space photography.

You can take some spectacular long exposure images with just a regular
tripod and the camera's normal lenses. If you want tracked images, get a
small equatorial mount with motorized star tracking and you *should* be able
to stay under budget.

If you want to get into deep sky photography, the cheapest setup I would
recommend would be the Orion 80ED on the Atlas mount. If you polar align
well enough on this mount, you can get as much as a minute exposures
without significant star trails. However, this setup would be about $1000 to
$1500 on the used market (www.astromart.com).

Just know going in that it's very hard to do deep sky work without spending
closer to $1000 (and that's really a low estimate) so I would start with
just the camera's lenses mounted on a small equatorial mount until you get
the hang of it and desire something more. But I will say, the pictures I've
seen with just this setup alone can be among the most spectacular. Here's an
example:

http://z.hubpages.com/u/101012_f520.jpg

If you want to try such photography, I think the following $115
"auto-tracking" eq mount would be an adequate place to start with low focal
length lenses:

http://www.telescope.com/control/product/~category_id=mounts_and_tripods/~pcateg\
ory=accessories/~product_id=09011

Just make sure you get the motorized option, which is extra.

You'll also need a manual shutter release which you could find at any camera
store.

Finally, you may want to check out www.hutech.com for information and
resources to modify (or have your camera modified) to be more sensitive to
the kinds of light that make night sky objects so beautiful. Standard
out-of-box DSLR cameras tend to filter out this light since it isn't useful
to terrestrial photography but the camera sensors are perfectly capable of a
much broader spectrum if their filter is replaced and hutech sells filters
that make your camera useful for both terrestrial and astrophotography. This
is something you'll almost certainly want to do regardless of whether you do
deep sky or simple camera/lense astrophotography.

I hope this helps.

Kelsey





On Sat, Nov 21, 2009 at 4:50 PM, James Prink <astroscuba1@...> wrote:

>
>
> One more thing to add to this post would be to join an astro club if you
> have one locally.  An average club will have a yearly membership fee of
> probably less than $50 and with that you get the use of all the equipment
> available. Plus the experience from other members.
> HTH
> Jim
>
> --- On Sat, 11/21/09, Rom Springall
<starman00@...<starman00%40netspace.net.au>>
> wrote:
>
> From: Rom Springall <starman00@...<starman00%40netspace.net.au>
> >
>
> Subject: [ccd-newastro] Re:Newbie with telescope questions
> To: ccd-newastro@yahoogroups.com <ccd-newastro%40yahoogroups.com>
> Date: Saturday, November 21, 2009, 4:16 PM
>
>
>
>
> Here is my advice, for what it is worth.
>
> Four hundred dollars wont buy you much of a telescope. A quick search on
> eBay will show you hundreds, if not thousands, of "department store"
> telescopes which are pretty useless and end up killing your interest with
> the frustration.
>
> If you want to get into deep sky photography, you would be better off
> investing in a decent lens to go with the camera and either build, or buy, a
> small mount that will allow you to track the movement of stars, for short
> periods of time. Anyone with even very modest skills can build a small
> equatorial platform in a day or so at very little cost.
>
> You can achieve good results with a basic DSLR and test the water in
> relation to your interest in astrophotography and many beautifl shots of the
> night sky have been done this way.
>
> If you want to do visual observing, for $400, I'd invest in a decent star
> atlas, (about $100), and a couple of good pairs of binoculars, (about 7 X
> 50's). Good binoculars will last a life time and can be used for lots of
> different activities.
>
> Once you've determined that you want to pursue the hobby, get a decent
> equatorial mount so that you can track for longer periods of time then
> invest in a small high quality refractor. You can do that for around $1000
> and it'll keep you happy for a ong time.
>
> Good luck, you are taking your first steps on a most amazing journey
>
> [Non-text portions of this message have been removed]
>
> [Non-text portions of this message have been removed]
>
>
>


[Non-text portions of this message have been removed]

I thought I would jump in here late with an observation and recommendation.  I
agree on the proposed budget, you need to start off with more realistic and
simplistic expectations.  Astrophotography is one of the hardest tasks in our
hobby.  A simple good, fast and well corrected camera lens on a DSLR would be
the best  place to start.  As far as the mount goes, I don't think you can touch
the price point with the very good AstroTrac mount.  I got a chance to repair
and use a damaged one and I was quite impressed with its capabilities.  I was
able to use up to 3 minute exposures at about 300mm FL and get nice tight stars.
And this was with a very improvised camera mounting arrangement with scavenged
bits from the old kit.  It was simply a matter of attaching my Kenko polar scope
to the mount and doing a couple minute polar alignment and I produced a quite
acceptable image of M31.  Used AstroTrac's show up on AstroMart often around the
$400-500 range.  MIght be a mount to consider.

Keith

Hi Everyone,

I just wanted to thank all of you for the great advice. I've been doing a lot of
research over the weekend and have a better understanding of what I'm getting
myself into. I took a few photos last night with my camera and was pleasantly
surprised at all the stars that showed up. I've always been interested in that
type of photography but never took the steps to get into it. I have far too many
hobbies.

I think for now I should focus on getting a decent telescope within my budget
and worry a little more about the deep space photos later, when I have a bigger
budget. I might invest in a tracking mount for my camera. I'm going to look at
all the links and advice everyone gave and go from there. I have a lot of books
on hold at the library and can't wait to dive in.

Thanks to all of you for the great advice. I'm going to thoroughly look into
this before making a purchase. I'm sure I'll have more questions at some point.

Thanks!

Rebecca








[Non-text portions of this message have been removed]

I keep running into a problem processing my images.  I start out with what looks
like a nice smooth image, and as soon as I start stretching it, the histogram
starts looking like a picket fence (i.e., spikes) and the image goes from smooth
to just a few discrete intensity levels.  I'm supposedly working with 16 bits
per pixel, but it quickly looks like it goes to about 5 or 6 bits per pixel
after only a few very modest stretches.  What am I doing wrong?

Any thoughts would be very welcome.  Thanks.

Rich

Are you in Photoshop?

You are right - that sounds like it is NOT a 16-bit file. Look at each step you
are doing - is anything converting you to an 8-bit image?

For example, saving to a TIFF in CCDSoft would, if memory serves, give you an
8-bit file.

You need to examine every step of your process and see if any part of it is
turning your data into an 8-bit image.

Ron W

On Nov 24, 2009, at 3:35 PM, richsmith79 wrote:

> I keep running into a problem processing my images.  I start out with what
looks like a nice smooth image, and as soon as I start stretching it, the
histogram starts looking like a picket fence (i.e., spikes) and the image goes
from smooth to just a few discrete intensity levels.  I'm supposedly working
with 16 bits per pixel, but it quickly looks like it goes to about 5 or 6 bits
per pixel after only a few very modest stretches.  What am I doing wrong?
>
> Any thoughts would be very welcome.  Thanks.
>
> Rich
>
>
>
> ------------------------------------
>
>
>
>

richsmith79 wrote:
> I keep running into a problem processing my images. I start out with
what looks like a nice smooth image, and as soon as I start stretching
it, the histogram starts looking like a picket fence (i.e., spikes) and
the image goes from smooth to just a few discrete intensity levels. I'm
supposedly working with 16 bits per pixel, but it quickly looks like it
goes to about 5 or 6 bits per pixel after only a few very modest
stretches. What am I doing wrong?
>
> Any thoughts would be very welcome.  Thanks.

If you are using adjustment layers then this is normal. When you merge
the layers you will get a smooth histogram again. Another way to get the
histogram smooth temporarily is to hit the recache button on the top
right of the histogram dialog.

If you are not using adjustment layers then you may be doing too many
odd stretches that pull the histogram apart, or perhaps you have
inadvertently imported as eight bit data.

Cheers, Paul.
--

Ron and Paul,

Thanks for the input.  I've been saving everything as 16 bit files in both FIT
and TIFF format, with similar results.  I don't seem to have an issue when I
save the files as separate R, G and B files in Nebulosity.  Each greyscale image
file looks very smooth.

After doing some additional experiments, I think I have a PhotoShop problem.  In
at least one case, as soon as I zoom a 16-bit RGB TIFF image created with
Nebulosity below 50%, the displayed image goes from very smooth to something
that looks like it has 4 bits per pixel.  Very odd. But in another case, zoom
has no affect on the blockiness of a 16-bit RGB TIFF image created with Deep Sky
Stacker.  Using FITS Liberator to create 16 bit files also creates blocky
images.

I'm confused.

--- In ccd-newastro@yahoogroups.com, Paul Beskeen <yahoo@...> wrote:
>
> richsmith79 wrote:
> > I keep running into a problem processing my images. I start out with
> what looks like a nice smooth image, and as soon as I start stretching
> it, the histogram starts looking like a picket fence (i.e., spikes) and
> the image goes from smooth to just a few discrete intensity levels. I'm
> supposedly working with 16 bits per pixel, but it quickly looks like it
> goes to about 5 or 6 bits per pixel after only a few very modest
> stretches. What am I doing wrong?
> >
> > Any thoughts would be very welcome.  Thanks.
>
> If you are using adjustment layers then this is normal. When you merge
> the layers you will get a smooth histogram again. Another way to get the
> histogram smooth temporarily is to hit the recache button on the top
> right of the histogram dialog.
>
> If you are not using adjustment layers then you may be doing too many
> odd stretches that pull the histogram apart, or perhaps you have
> inadvertently imported as eight bit data.
>
> Cheers, Paul.
> --
>

There is something else- but I don't want to confuse the matter- so ignore this
if it is not relevant.

You can get the effect you describe when saving 16-bit INTEGER TIF files for
Photoshop. The original floating point file that you have created (presumably in
Maxim DL or CCDStack...etc) contains fractional values (values to the right of
the decimal). These fractional values are dropped in the creation of the 16-bit
integer TIF.

This quantization artifact sometimes happens for me when dealing with Ha data
since the range of values is so small those fractional values can make a
difference. Scaling data (by multiplying by some reasonable number) before
saving as a 16-bit (integer) file can help pull some of those fractional values
to be expressed in the integer file.

Nowadays if I am blending Ha data this happens naturally for me when I normalize
the Ha data to the luminance or Red information.

Anyway, just felt like babbling a little bit.
Adam


------------------------------------------------------------
Adam Block

ngc1535@...

http://skycenter.arizona.edu (NEW!)

http://caelumobservatory.com/

Caelum videre iussit, et erectos ad sidera tollere vultus.
He bid them look at the sky and lift their faces to the stars.
--Ovid, Metamorphoses 1. 85-8

------------------------------------------------------------


 

 

*-----Original Message-----
*From: richsmith79 [mailto:smithrb@...]
*Sent: Tuesday, November 24, 2009 03:35 PM
*To: ccd-newastro@yahoogroups.com
*Subject: [ccd-newastro] Where are my smooth levels going?
*
*I keep running into a problem processing my images.  I start out with what
looks like a nice smooth image, and as soon as I start stretching it, the
histogram starts looking like a picket fence (i.e., spikes) and the image goes
from smooth to just a few discrete intensity levels.  I'm supposedly working
with 16 bits per pixel, but it quickly looks like it goes to about 5 or 6 bits
per pixel after only a few very modest stretches.  What am I doing wrong?
*
*Any thoughts would be very welcome.  Thanks.
*
*Rich
*
*

Adam, sounds like a topic for a future tutorial.

Larry


--- In ccd-newastro@yahoogroups.com, "Adam Block" <ngc1535@...> wrote:
>
> There is something else- but I don't want to confuse the matter- so ignore
this if it is not relevant.
>
> You can get the effect you describe when saving 16-bit INTEGER TIF files for
Photoshop. The original floating point file that you have created (presumably in
Maxim DL or CCDStack...etc) contains fractional values (values to the right of
the decimal). These fractional values are dropped in the creation of the 16-bit
integer TIF.
>
> This quantization artifact sometimes happens for me when dealing with Ha data
since the range of values is so small those fractional values can make a
difference. Scaling data (by multiplying by some reasonable number) before
saving as a 16-bit (integer) file can help pull some of those fractional values
to be expressed in the integer file.
>
> Nowadays if I am blending Ha data this happens naturally for me when I
normalize the Ha data to the luminance or Red information.
>
> Anyway, just felt like babbling a little bit.
> Adam
>
>
> ------------------------------------------------------------
> Adam Block
>
> ngc1535@...
>
> http://skycenter.arizona.edu (NEW!)
>
> http://caelumobservatory.com/
>
> Caelum videre iussit, et erectos ad sidera tollere vultus.
> He bid them look at the sky and lift their faces to the stars.
> --Ovid, Metamorphoses 1. 85-8
>
> ------------------------------------------------------------
>
>
>  
>
>  
>
> *-----Original Message-----
> *From: richsmith79 [mailto:smithrb@...]
> *Sent: Tuesday, November 24, 2009 03:35 PM
> *To: ccd-newastro@yahoogroups.com
> *Subject: [ccd-newastro] Where are my smooth levels going?
> *
> *I keep running into a problem processing my images.  I start out with what
looks like a nice smooth image, and as soon as I start stretching it, the
histogram starts looking like a picket fence (i.e., spikes) and the image goes
from smooth to just a few discrete intensity levels.  I'm supposedly working
with 16 bits per pixel, but it quickly looks like it goes to about 5 or 6 bits
per pixel after only a few very modest stretches.  What am I doing wrong?
> *
> *Any thoughts would be very welcome.  Thanks.
> *
> *Rich
> *
> *
>

On Friday (Nov 27, 2009), enter the coupon code BLACKFRIDAY on the checkout page
and receive a 50% discount on everything, including new subscriptions,
subscription renewals/extensions, individual back issues and conference DVDs.

http://www.astrophotoinsight.com/catalog

Clear skies,
Al Degutis
Editor-in-Chief
AstroPhoto Insight Magazine
http://www.astrophotoinsight.com

Adam, you were not babbling at all.  You hit the nail on the head and solved my
problem.  Thanks so much.

Rich

--- In ccd-newastro@yahoogroups.com, "Adam Block" <ngc1535@...> wrote:
>
> There is something else- but I don't want to confuse the matter- so ignore
this if it is not relevant.
>
> You can get the effect you describe when saving 16-bit INTEGER TIF files for
Photoshop. The original floating point file that you have created (presumably in
Maxim DL or CCDStack...etc) contains fractional values (values to the right of
the decimal). These fractional values are dropped in the creation of the 16-bit
integer TIF.
>
> This quantization artifact sometimes happens for me when dealing with Ha data
since the range of values is so small those fractional values can make a
difference. Scaling data (by multiplying by some reasonable number) before
saving as a 16-bit (integer) file can help pull some of those fractional values
to be expressed in the integer file.
>
> Nowadays if I am blending Ha data this happens naturally for me when I
normalize the Ha data to the luminance or Red information.
>
> Anyway, just felt like babbling a little bit.
> Adam
>
>
> ------------------------------------------------------------
> Adam Block
>
> ngc1535@...
>
> http://skycenter.arizona.edu (NEW!)
>
> http://caelumobservatory.com/
>
> Caelum videre iussit, et erectos ad sidera tollere vultus.
> He bid them look at the sky and lift their faces to the stars.
> --Ovid, Metamorphoses 1. 85-8
>
> ------------------------------------------------------------
>
>
>  
>
>  
>
> *-----Original Message-----
> *From: richsmith79 [mailto:smithrb@...]
> *Sent: Tuesday, November 24, 2009 03:35 PM
> *To: ccd-newastro@yahoogroups.com
> *Subject: [ccd-newastro] Where are my smooth levels going?
> *
> *I keep running into a problem processing my images.  I start out with what
looks like a nice smooth image, and as soon as I start stretching it, the
histogram starts looking like a picket fence (i.e., spikes) and the image goes
from smooth to just a few discrete intensity levels.  I'm supposedly working
with 16 bits per pixel, but it quickly looks like it goes to about 5 or 6 bits
per pixel after only a few very modest stretches.  What am I doing wrong?
> *
> *Any thoughts would be very welcome.  Thanks.
> *
> *Rich
> *
> *
>