Danny, unless I'm dreaming it...I looked at Orion's ad for the camera on
their site when I received my catalog w/o a price and it was $2900. A day or two
later SBIG announced their version for under $2K and now the Orion is priced at
$2599...Still way too high IMHO. I suppose that's justified by their 4 position
cheap(er) filter wheel and their much cheaper 2" filters to fit it. I don't know
about the camera, but in the case of the CFW and in particular the filters...you
usually get what you pay for...

    BTW: I also think the Orion has an electronic shutter vice mechanical because
of the speed listed. This means you can shoot brighter objects using the faster
shutter speed but probably need to physically cover the OTA to take a dark.

Stu

   ----- Original Message -----
   From: dannysperry
   To: ccd-newastro@yahoogroups.com
   Sent: Monday, November 16, 2009 12:57 AM
   Subject: [ccd-newastro] Re: Camera question - reflection



   I think the main thing contributing to the different pricing is that each of
the various companies guessed wrong on where SBIG would come in price-wise.
Orion may have a hard time selling the $2600 monochrome Parsec now that SBIG has
announced their $2000 camera with the same chip. FLI, Apogee, and QSI would be
wise to lower their prices on their 8300-based cameras. Of course, they could
get stubborn on the issue and insist there are all sorts of features and support
that separate them from Orion... but how are they going to make that argument
against SBIG? :-)

   Best,
   Danny

   --- In ccd-newastro@yahoogroups.com, "Matts Sporre" <matts.sporre@...> wrote:
   >
   > Dear group
   >
   >
   >
   > In recent days two new cameras has been introduced; the Orion Persec 8300
   > and the SBIG ST-8300. From before we have the QSI 583.
   >
   >
   >
   > They all have the same sensor Kodak's KAF-8300 sensor, but the price is
   > really different. The QSI starts at $3595 (then you can add filter wheel and
   > OAG for more $), the Orion is priced at $2500 and the SBIG at $1995. All
   > have regulating temp, at least QSI and SBIG have mechanical shutter (not
   > sure about the Orion).
   >
   >
   >
   > What am I missing?
   >
   >
   >
   > BR
   > Matts
   >
   >
   >
   > _____
   >
   > Frεn: ccd-newastro@yahoogroups.com [mailto:ccd-newastro@yahoogroups.com] Fφr
   > njsgps
   > Skickat: den 9 november 2009 20:24
   > Till: ccd-newastro@yahoogroups.com
   > Δmne: [ccd-newastro] CCD FOV Calculator
   >
   >
   >
   >
   >
   > Hi all,
   >
   > I just changed to the latest (and last) version of Ron's CCD Calculator
   > program, and find that I can no longer 'drag' the little FOV window around
   > the sample images. It only ever appears 'dead centre', and can only be
   > 'moved' by 'clicking and dragging' with the mouse - which just draws a new
   > window, with sizes commensurate with where the mouse 'clicked'.
   >
   > Is this how the latest (v1.5.0 (c)2002) version works?
   >
   > Cheers,
   > Niall Saunders
   > Clinterty Observatories
   > Aberdeen, SCOTLAND
   >
   >
   >
   >
   >
   > [Non-text portions of this message have been removed]
   >





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

Ron,

I don't think this is what Luis is asking.  Luis would need to respond, but,
It looks like he is asking is if a master dark consisting of summing 30
frames of 30 seconds each (900 sec. total exposure time) is equivalent, or
equal quality to, a master dark consisting of 3 frames of 300 seconds each
(again 900 sec. total exposure time).

For my dark library, I usually expose an equal number of exposures for each
duration and mediam combine each set for a master dark of its respective
exposure duration.

Don Waid

----- Original Message -----
From: "Wodaski - Yahoo" <yahoo@...>
To: <ccd-newastro@yahoogroups.com>
Sent: Sunday, November 15, 2009 10:36 PM
Subject: Re: [ccd-newastro] Dark frame libraries


> I'm confused by what you are asking; it looks like you are asking about
> something that absolutely won't work: summing 30-second darks to get
> longer darks.
>
> No, won't work at all. The bias will be completely wrong in the summed
> result.
>
> Ron W
>
> On Nov 15, 2009, at 5:48 PM, lbarneo2003 wrote:
>
>> Ron,
>> If I obtain 30 dark frames, 30 seconds each one, is it correct to
>> construct various  libraries applying the sum of the frames such as: 15
>> dark frames of 60 seconds each one,  10 dark frames of  90 seconds each
>> one, 5 dark frames of 180 seconds each one, 3 dark frames of 300 seconds
>> each one, etc? Thanks,
>> Luis
>>
>>
>>
>>
>> ------------------------------------
>>
>>
>>
>>
>
>
>
> ------------------------------------
>
>
>
>

I think the main thing contributing to the different pricing is that each of the
various companies guessed wrong on where SBIG would come in price-wise. Orion
may have a hard time selling the $2600 monochrome Parsec now that SBIG has
announced their $2000 camera with the same chip. FLI, Apogee, and QSI would be
wise to lower their prices on their 8300-based cameras. Of course, they could
get stubborn on the issue and insist there are all sorts of features and support
that separate them from Orion... but how are they going to make that argument
against SBIG? :-)

Best,
Danny


--- In ccd-newastro@yahoogroups.com, "Matts Sporre" <matts.sporre@...> wrote:
>
> Dear group
>
>
>
> In recent days two new cameras has been introduced; the Orion Persec 8300
> and the SBIG ST-8300. From before we have the QSI 583.
>
>
>
> They all have the same sensor Kodak's KAF-8300 sensor, but the price is
> really different. The QSI starts at $3595 (then you can add filter wheel and
> OAG for more $), the Orion is priced at $2500 and the SBIG at $1995. All
> have regulating temp, at least QSI and SBIG have mechanical shutter (not
> sure about the Orion).
>
>
>
> What am I missing?
>
>
>
> BR
> Matts
>
>
>
>   _____
>
> Frεn: ccd-newastro@yahoogroups.com [mailto:ccd-newastro@yahoogroups.com] Fφr
> njsgps
> Skickat: den 9 november 2009 20:24
> Till: ccd-newastro@yahoogroups.com
> Δmne: [ccd-newastro] CCD FOV Calculator
>
>
>
>
>
> Hi all,
>
> I just changed to the latest (and last) version of Ron's CCD Calculator
> program, and find that I can no longer 'drag' the little FOV window around
> the sample images. It only ever appears 'dead centre', and can only be
> 'moved' by 'clicking and dragging' with the mouse - which just draws a new
> window, with sizes commensurate with where the mouse 'clicked'.
>
> Is this how the latest (v1.5.0 (c)2002) version works?
>
> Cheers,
> Niall Saunders
> Clinterty Observatories
> Aberdeen, SCOTLAND
>
>
>
>
>
> [Non-text portions of this message have been removed]
>

I'm confused by what you are asking; it looks like you are asking about
something that absolutely won't work: summing 30-second darks to get longer
darks.

No, won't work at all. The bias will be completely wrong in the summed result.

Ron W

On Nov 15, 2009, at 5:48 PM, lbarneo2003 wrote:

> Ron,
> If I obtain 30 dark frames, 30 seconds each one, is it correct to construct
various  libraries applying the sum of the frames such as: 15 dark frames of 60
seconds each one,  10 dark frames of  90 seconds each one, 5 dark frames of 180
seconds each one, 3 dark frames of 300 seconds each one, etc? Thanks,
> Luis
>
>
>
>
> ------------------------------------
>
>
>
>

Ron,
If I obtain 30 dark frames, 30 seconds each one, is it correct to construct
various  libraries applying the sum of the frames such as: 15 dark frames of 60
seconds each one,  10 dark frames of  90 seconds each one, 5 dark frames of 180
seconds each one, 3 dark frames of 300 seconds each one, etc? Thanks,
Luis

Ryan, all dielectric-coated filters are "mirrors" outside their bandpass,
including red, green and blue and narrowbands. The key is how the manufacturer
designs the coatings on both sides of the filter.  Since A/R is built into the
design, you don't or shouldn't get much of Fresnel reflections (4% reflectivity
per side).  The ghosting that produces halos around bright stars is "cross-talk"
between the two sides of the filter where the coatings are not quite designed
correctly.  You'll have to go by comments posted on the web to determine which
narrowband filters have and do not have these halo problems.  Since the filter
is a mirror outside the bandpass, the filter will reject, that is, reflect this
unwanted light back up through the telescope. It shouldn't reach your CCD. In
general, you should see H-a images, let's say of the Horsehead Nebula, where
hugely bright Alnitak is just a big star.  That means that the H-a filter is
doing its job.  Again, the best way to assess this is to look at posted images
on these groups and ask around to see which brand has or doesn't have halos and
reflections.

Don Goldman
Astrodon Imaging




--- In ccd-newastro@yahoogroups.com, Ryan Brooks <ryan@...> wrote:
>
> Any thoughts on the "mirror" issue?  I've got the same issue right now,
> so I stay away from objects with bright stars nestled in nebulousity.
>
> donclearview wrote:
> >
> >
> > We guarantee >90% transmission at the emission line for our 5 and 3 nm
> > Astrodon narrowband filters. Transmission dominates your Signal (S) in
> > S/N. S/N is contrast. The N is largely controlled by the FWHM of the
> > filter that eliminates continuum radiation outside the filter's
> > bandpass. The narrower the filter, the more is eliminated, bringing
> > out faint detail, and minimizing moonlight gradients. For example,
> > going from a 6 to a 3 nm filter decreases the background ADU signal
> > that you measure in your FITS file by over 2x. This leads to an
> > increase in S/N of about 25%. You don't see a huge difference in the
> > bright parts of the nebula. You will see it out in the fainter areas,
> > such as outer halos in planetary nebula and in background nebulosity.
> >
> > An example of 3 nm vs 6 nm OIII taken with the moon out is shown at:
> > http://old.astrodon.com/oldsite/6v3/6v3.html
> > <http://old.astrodon.com/oldsite/6v3/6v3.html>
> >
> > I've written a short FAQ on narrowbands at:
> > http://www.astrodon.com/Orphan/astrodonfaqnarrowband/
> > <http://www.astrodon.com/Orphan/astrodonfaqnarrowband/>
> >
> > Regards,
> > Don Goldman
> > Astrodon Imaging
> >
> > --- In ccd-newastro@yahoogroups.com
> > <mailto:ccd-newastro%40yahoogroups.com>, "dennis_persyk" <dpersyk@>
> > wrote:
> > >
> > > Hello Bob,
> > >
> > > Thanks for the kind words.
> > >
> > > The main thing for me is that it is an AstroDon filter. I have
> > another brand, wider than 6 nm FWHM, that has terrible problems with
> > reflections that produce halos and ghosting. If you notice, the H-a
> > filterer is a pretty good mirror. This leads to all sorts of problems,
> > as the Si chip is itself a good mirror (Fresnel reflections).
> > >
> > > To my knowledge, the peak transmission of an H-a filter is not
> > guaranteed – the suppliers offer "typical" curves but guarantee no
> > specs. I will probably get a narrower filter in the future. I want the
> > best SNR, and that to me means the narrowest filter. The H-a line from
> > the nebulae are neither pressure broadened nor red-shifted, so why not
> > use the narrowest filter compatible with your scope's focal ratio?
> > >
> > > Clear skies,
> > >
> > > Dennis
> > >
> > >
> > > --- In ccd-newastro@yahoogroups.com
> > <mailto:ccd-newastro%40yahoogroups.com>, "tekic545" <tekic545@> wrote:
> > > >
> > > > Dennis,
> > > >
> > > > Excellent summary. What do you see as the pros and cons of a 6 nm
> > Ha filter vs wider passband such as 13 nm, for a fast astrography like
> > yours?
> > > >
> > > > Bob
> > > >
> > > > --- In ccd-newastro@yahoogroups.com
> > <mailto:ccd-newastro%40yahoogroups.com>, "dennis_persyk" <dpersyk@> wrote:
> > > > >
> > > > > Our skies are filled with nebulae. The nebulae of interest in
> > this tutorial are huge regions of gas – gas clouds. The nebulae I'll
> > discuss here are called emission nebulae. We image emission nebulae by
> > means of the light from the surrounding gas cloud which is ionized by
> > radiation from one or more nearby stars.
> > > > >
> > > > > The most common emission nebulae are of the hydrogen emission
> > type. They emit a very narrow band of red light, and with the
> > appropriate filter (Hydrogen alpha, or H-a), the camera sees
> > essentially only the nebula light, and moon light and terrestrial
> > light pollution is nearly completely eliminated.
> > > > >
> > > > > Imaging with H-a levels the imaging playing field. No matter
> > where you are imaging from, with an H-a filter you have the equivalent
> > of magnitude 8 super dark skies! Honest!
> > > > >
> > > > > Pros of H-a Imaging
> > > > > • Eliminates light pollution
> > > > > • Background is now inky black – backgrounds have a zero or
> > nearly zero black point
> > > > > • Stars are much dimmer, minimizing star bloat, chromatic
> > aberration and "fat" stars.
> > > > >
> > > > > Cons of H-a Imaging
> > > > > • Very little signal is passed by the filter, so imaging times
> > have to be fairly long – five minute subs are possible if your camera
> > has very low readout noise
> > > > > • Autoguiding is probably required
> > > > > • DLSRs without mods don't have much sensitivity to the H-a light
> > > > >
> > > > > Here's an example of 2 hours and 15 minutes in nine 15-minute
> > subframes
> > > > > http://home.att.net/~dpersyk/new.htm
> > <http://home.att.net/%7Edpersyk/new.htm>
> > > > >
> > > > > The target is NGC 281, a/k/a the "Pac Man" nebula and Sharpless
> > 2-184. I used a Takahashi astrograph, f/3.3 and Starlight Xpress
> > SXV-H9 camera. The filter was a 6 nm FWHM H-a. Most processing was
> > done with ImagesPlus. The false color was added in Photoshop with Noel
> > Carboni's actions. The Hubble employes false color, so I don't feel
> > like I cheated.
> > > > >
> > > > > I recommend H-a imaging to everyone who is plagued by sky
> > pollution. No longer will you have to journey to a dark site to get
> > good images.
> > > > >
> > > > > Clear skies,
> > > > >
> > > > > Dennis Persyk
> > > > > Igloo (Now Roll-Off) Observatory Home Page
> > http://dpersyk.home.att.net <http://dpersyk.home.att.net>
> > > > > Hampshire, IL
> > > > >
> > > >
> > >
> >
> >
>

Matts,

There are lots of things to look at besides the base price of the camera. The
Orion cameras have in the past, always had a lot of pattern noise, this is an
unknown at this time. A lot of the cost of making a camera is in the price of
the electronics, and if the electronics are not designed well then you will get
pattern noise which does not calibrate out. The Orion will also require 2"
filters which are more expensive, this is due to the distance from the sensor to
the filter and with smaller filters will cause vignetting. The SBIG gets around
this with a new filter wheel that uses a custom sized filters, so expect to add
another $1200-1500 to the SBIG to start imaging. The Orion will be much the same
maybe a little less, but you will want high quality filters so that will bring
it closer in cost. Also if you want any narrowband filters the larger filters
are a lot more expensive than 1 1/4 filters. The QSI camera uses the smaller
filters because the filter wheel is closer to the sensor so you can use the 1
1/4 filters without any vingetting up to about f2.8 and any faster there will be
some slight vignetting but will flat field out. The QSI also has the intergrated
off-axis guider, so that reduces the amount of backfocus necessary and
eliminates flexure and works with a number of popular guide cameras. The other
cameras will require an external off-axis guider which will need more backfocus.
If you choose an external guide scope then you can get flexure issues. The QSI
also has very low noise, very closely regulated temperature and is available
now.

So when you look it with all the things needed they get a lot closer in price to
each other, so then you need to look which is going to give you the best image,
the best image data to start with results in less editing, less headaches and
easier editing. So look at the whole package not the just the initial cost of
the camera.

Alan

--- In ccd-newastro@yahoogroups.com, "Matts Sporre" <matts.sporre@...> wrote:
>
> Dear group
>
>
>
> In recent days two new cameras has been introduced; the Orion Persec 8300
> and the SBIG ST-8300. From before we have the QSI 583.
>
>
>
> They all have the same sensor Kodak's KAF-8300 sensor, but the price is
> really different. The QSI starts at $3595 (then you can add filter wheel and
> OAG for more $), the Orion is priced at $2500 and the SBIG at $1995. All
> have regulating temp, at least QSI and SBIG have mechanical shutter (not
> sure about the Orion).
>
>
>
> What am I missing?
>
>
>
> BR
> Matts
>
>

Any thoughts on the "mirror" issue?  I've got the same issue right now,
so I stay away from objects with bright stars nestled in nebulousity.

donclearview wrote:
>
>
> We guarantee >90% transmission at the emission line for our 5 and 3 nm
> Astrodon narrowband filters. Transmission dominates your Signal (S) in
> S/N. S/N is contrast. The N is largely controlled by the FWHM of the
> filter that eliminates continuum radiation outside the filter's
> bandpass. The narrower the filter, the more is eliminated, bringing
> out faint detail, and minimizing moonlight gradients. For example,
> going from a 6 to a 3 nm filter decreases the background ADU signal
> that you measure in your FITS file by over 2x. This leads to an
> increase in S/N of about 25%. You don't see a huge difference in the
> bright parts of the nebula. You will see it out in the fainter areas,
> such as outer halos in planetary nebula and in background nebulosity.
>
> An example of 3 nm vs 6 nm OIII taken with the moon out is shown at:
> http://old.astrodon.com/oldsite/6v3/6v3.html
> <http://old.astrodon.com/oldsite/6v3/6v3.html>
>
> I've written a short FAQ on narrowbands at:
> http://www.astrodon.com/Orphan/astrodonfaqnarrowband/
> <http://www.astrodon.com/Orphan/astrodonfaqnarrowband/>
>
> Regards,
> Don Goldman
> Astrodon Imaging
>
> --- In ccd-newastro@yahoogroups.com
> <mailto:ccd-newastro%40yahoogroups.com>, "dennis_persyk" <dpersyk@...>
> wrote:
> >
> > Hello Bob,
> >
> > Thanks for the kind words.
> >
> > The main thing for me is that it is an AstroDon filter. I have
> another brand, wider than 6 nm FWHM, that has terrible problems with
> reflections that produce halos and ghosting. If you notice, the H-a
> filterer is a pretty good mirror. This leads to all sorts of problems,
> as the Si chip is itself a good mirror (Fresnel reflections).
> >
> > To my knowledge, the peak transmission of an H-a filter is not
> guaranteed – the suppliers offer "typical" curves but guarantee no
> specs. I will probably get a narrower filter in the future. I want the
> best SNR, and that to me means the narrowest filter. The H-a line from
> the nebulae are neither pressure broadened nor red-shifted, so why not
> use the narrowest filter compatible with your scope's focal ratio?
> >
> > Clear skies,
> >
> > Dennis
> >
> >
> > --- In ccd-newastro@yahoogroups.com
> <mailto:ccd-newastro%40yahoogroups.com>, "tekic545" <tekic545@> wrote:
> > >
> > > Dennis,
> > >
> > > Excellent summary. What do you see as the pros and cons of a 6 nm
> Ha filter vs wider passband such as 13 nm, for a fast astrography like
> yours?
> > >
> > > Bob
> > >
> > > --- In ccd-newastro@yahoogroups.com
> <mailto:ccd-newastro%40yahoogroups.com>, "dennis_persyk" <dpersyk@> wrote:
> > > >
> > > > Our skies are filled with nebulae. The nebulae of interest in
> this tutorial are huge regions of gas – gas clouds. The nebulae I'll
> discuss here are called emission nebulae. We image emission nebulae by
> means of the light from the surrounding gas cloud which is ionized by
> radiation from one or more nearby stars.
> > > >
> > > > The most common emission nebulae are of the hydrogen emission
> type. They emit a very narrow band of red light, and with the
> appropriate filter (Hydrogen alpha, or H-a), the camera sees
> essentially only the nebula light, and moon light and terrestrial
> light pollution is nearly completely eliminated.
> > > >
> > > > Imaging with H-a levels the imaging playing field. No matter
> where you are imaging from, with an H-a filter you have the equivalent
> of magnitude 8 super dark skies! Honest!
> > > >
> > > > Pros of H-a Imaging
> > > > • Eliminates light pollution
> > > > • Background is now inky black – backgrounds have a zero or
> nearly zero black point
> > > > • Stars are much dimmer, minimizing star bloat, chromatic
> aberration and "fat" stars.
> > > >
> > > > Cons of H-a Imaging
> > > > • Very little signal is passed by the filter, so imaging times
> have to be fairly long – five minute subs are possible if your camera
> has very low readout noise
> > > > • Autoguiding is probably required
> > > > • DLSRs without mods don't have much sensitivity to the H-a light
> > > >
> > > > Here's an example of 2 hours and 15 minutes in nine 15-minute
> subframes
> > > > http://home.att.net/~dpersyk/new.htm
> <http://home.att.net/%7Edpersyk/new.htm>
> > > >
> > > > The target is NGC 281, a/k/a the "Pac Man" nebula and Sharpless
> 2-184. I used a Takahashi astrograph, f/3.3 and Starlight Xpress
> SXV-H9 camera. The filter was a 6 nm FWHM H-a. Most processing was
> done with ImagesPlus. The false color was added in Photoshop with Noel
> Carboni's actions. The Hubble employes false color, so I don't feel
> like I cheated.
> > > >
> > > > I recommend H-a imaging to everyone who is plagued by sky
> pollution. No longer will you have to journey to a dark site to get
> good images.
> > > >
> > > > Clear skies,
> > > >
> > > > Dennis Persyk
> > > > Igloo (Now Roll-Off) Observatory Home Page
> http://dpersyk.home.att.net <http://dpersyk.home.att.net>
> > > > Hampshire, IL
> > > >
> > >
> >
>
>

Sheldon,

I don't see any reason a manual filter wheel would not work.  You may be
able to get one of these plus filters on Astromart.  Don't forget to check
on Cloudy Nights also.  They have a similar feature like Astromart for used
equipment.  Manual wheel or not, don't skimp on the filters.  I have seen
complete sets of CS filters on Astromart for around a hundred or so.

Don

----- Original Message -----
From: "taldan9" <alfortz9@...>
To: <ccd-newastro@yahoogroups.com>
Sent: Sunday, November 15, 2009 3:01 PM
Subject: [ccd-newastro] Re: Colour through an SBIG 237a - manual filters


> Don,
>
> Thanks, i have 3 ads out there now. just curious though, since i will not
> be spending the $400 or so necessary to buy the cfw5 at the 2 suppliers
> that still sell it new, would a manual tri-color filter, like lumicon's,
> work with the 237a?
>
> I am trying to be as frugal as possible while in the beginner stage.
>
> sheldon
>
>
> --- In ccd-newastro@yahoogroups.com, "Don" <don@...> wrote:
>>
>> Hi,
>>
>> You might try putting a "want ad" for a cfw-5c on Astromart.  You might
>> just
>> get lucky!
>>
>> Good luck,
>>
>> Don Waid
>> http://www.waid-observatory.com
>>
>> ----- Original Message -----
>> From: "taldan9" <alfortz9@...>
>> To: <ccd-newastro@yahoogroups.com>
>> Sent: Thursday, November 12, 2009 3:14 PM
>> Subject: [ccd-newastro] Colour through an SBIG 237a
>>
>>
>> >I know this question might be better at the SBIG group, but as an abject
>> >beginner I thought I would post it here first.
>> >
>> > I have, spending very little, acquired an SBIG 237a (at a store
>> > close-out
>> > of abandoned consignment items) and the SBIG efinder/focal reducer, so
>> > the
>> > only item missing from my perspective is the colour filter wheel and
>> > filters.
>> >
>> > Is the SBIG internal cfw/filters system necessary to take colour
>> > pictures
>> > with this camera or is there another way of doing it?  I have come
>> > across
>> > references to SBIG compatible CFWs, but can't get any information about
>> > them and the internal cfw-5c which was made by SBIG for the 237 has
>> > long
>> > been discontinued.
>> >
>> >
>> > Sheldon
>> >
>> >
>> >
>> >
>> >
>> > ------------------------------------
>> >
>> >
>> >
>> >
>>
>
>
>
>
> ------------------------------------
>
>
>
>

We guarantee >90% transmission at the emission line for our 5 and 3 nm Astrodon
narrowband filters.  Transmission dominates your Signal (S) in S/N.  S/N is
contrast.   The N is largely controlled by the FWHM of the filter that
eliminates continuum radiation outside the filter's bandpass. The narrower the
filter, the more is eliminated, bringing out faint detail, and minimizing
moonlight gradients. For example, going from a 6 to a 3 nm filter decreases the
background ADU signal that you measure in your FITS file by over 2x. This leads
to an increase in S/N of about 25%.  You don't see a huge difference in the
bright parts of the nebula.  You will see it out in the fainter areas, such as
outer halos in planetary nebula and in background nebulosity.

An example of 3 nm vs 6 nm OIII taken with the moon out is shown at:
http://old.astrodon.com/oldsite/6v3/6v3.html

I've written a short FAQ on narrowbands at:
http://www.astrodon.com/Orphan/astrodonfaqnarrowband/

Regards,
Don Goldman
Astrodon Imaging

--- In ccd-newastro@yahoogroups.com, "dennis_persyk" <dpersyk@...> wrote:
>
> Hello Bob,
>
> Thanks for the kind words.
>
> The main thing for me is that it is an  AstroDon filter. I have another brand,
wider than 6 nm FWHM, that has terrible problems with reflections that produce
halos and ghosting. If you notice, the H-a filterer is a pretty good mirror.
This leads to all sorts of problems, as the Si chip is itself a good mirror
(Fresnel reflections).
>
> To my knowledge, the peak transmission  of an H-a filter is not guaranteed –
the suppliers offer "typical" curves but guarantee no specs. I will probably get
a narrower filter in the future. I want the best SNR, and that to me means the
narrowest filter. The H-a line from the nebulae are neither pressure broadened
nor red-shifted, so why not use the narrowest filter compatible with your
scope's focal ratio?
>
> Clear skies,
>
> Dennis
>
>
> --- In ccd-newastro@yahoogroups.com, "tekic545" <tekic545@> wrote:
> >
> > Dennis,
> >
> > Excellent summary. What do you see as the pros and cons of a 6 nm Ha filter
vs wider passband such as 13 nm, for a fast astrography like yours?
> >
> > Bob
> >
> > --- In ccd-newastro@yahoogroups.com, "dennis_persyk" <dpersyk@> wrote:
> > >
> > > Our skies are filled with nebulae. The nebulae of interest in this
tutorial are huge regions of gas – gas clouds. The nebulae I'll discuss here are
called emission nebulae. We image emission nebulae by means of the light from
the surrounding  gas cloud which is ionized by radiation from one or more nearby
stars.
> > >
> > > The most common emission nebulae are of the hydrogen emission type. They
emit a very narrow band of red light, and with the appropriate filter (Hydrogen
alpha, or H-a), the camera sees essentially only the nebula light, and moon
light and terrestrial light pollution is nearly completely eliminated.
> > >
> > > Imaging with H-a levels the imaging playing field. No matter where you are
imaging from, with an H-a filter you have the equivalent of magnitude 8 super
dark skies! Honest!
> > >
> > > Pros of H-a Imaging
> > > • Eliminates light pollution
> > > • Background is now inky black – backgrounds have a  zero or nearly zero
black point
> > > • Stars are much dimmer, minimizing star bloat, chromatic aberration and
"fat" stars.
> > >
> > > Cons of   H-a Imaging
> > > • Very little signal is passed by the filter, so imaging times have to be
fairly long – five minute subs are possible if your camera has very low readout
noise
> > > • Autoguiding is probably required
> > > • DLSRs without mods don't have much sensitivity to the H-a light
> > >
> > > Here's an example of 2 hours and 15 minutes in nine 15-minute subframes
> > > http://home.att.net/~dpersyk/new.htm
> > >
> > > The target is NGC 281, a/k/a the "Pac Man" nebula and Sharpless 2-184. I
used a Takahashi astrograph, f/3.3 and Starlight Xpress SXV-H9 camera. The
filter was a 6 nm FWHM H-a. Most processing was done with ImagesPlus.  The false
color was added in Photoshop with Noel Carboni's actions. The Hubble employes
false color, so I don't feel like I cheated.
> > >
> > > I recommend H-a imaging to everyone who is plagued by sky pollution. No
longer will you have to journey to a dark site to get good images.
> > >
> > > Clear skies,
> > >
> > > Dennis Persyk
> > > Igloo (Now Roll-Off) Observatory Home Page http://dpersyk.home.att.net
> > > Hampshire, IL
> > >
> >
>

Don,

Thanks, i have 3 ads out there now. just curious though, since i will not be
spending the $400 or so necessary to buy the cfw5 at the 2 suppliers that still
sell it new, would a manual tri-color filter, like lumicon's, work with the
237a?

I am trying to be as frugal as possible while in the beginner stage.

sheldon


--- In ccd-newastro@yahoogroups.com, "Don" <don@...> wrote:
>
> Hi,
>
> You might try putting a "want ad" for a cfw-5c on Astromart.  You might just
> get lucky!
>
> Good luck,
>
> Don Waid
> http://www.waid-observatory.com
>
> ----- Original Message -----
> From: "taldan9" <alfortz9@...>
> To: <ccd-newastro@yahoogroups.com>
> Sent: Thursday, November 12, 2009 3:14 PM
> Subject: [ccd-newastro] Colour through an SBIG 237a
>
>
> >I know this question might be better at the SBIG group, but as an abject
> >beginner I thought I would post it here first.
> >
> > I have, spending very little, acquired an SBIG 237a (at a store close-out
> > of abandoned consignment items) and the SBIG efinder/focal reducer, so the
> > only item missing from my perspective is the colour filter wheel and
> > filters.
> >
> > Is the SBIG internal cfw/filters system necessary to take colour pictures
> > with this camera or is there another way of doing it?  I have come across
> > references to SBIG compatible CFWs, but can't get any information about
> > them and the internal cfw-5c which was made by SBIG for the 237 has long
> > been discontinued.
> >
> >
> > Sheldon
> >
> >
> >
> >
> >
> > ------------------------------------
> >
> >
> >
> >
>

Hello Bob,

Thanks for the kind words.

The main thing for me is that it is an  AstroDon filter. I have another brand,
wider than 6 nm FWHM, that has terrible problems with reflections that produce
halos and ghosting. If you notice, the H-a filterer is a pretty good mirror.
This leads to all sorts of problems, as the Si chip is itself a good mirror
(Fresnel reflections).

To my knowledge, the peak transmission  of an H-a filter is not guaranteed – the
suppliers offer "typical" curves but guarantee no specs. I will probably get a
narrower filter in the future. I want the best SNR, and that to me means the
narrowest filter. The H-a line from the nebulae are neither pressure broadened
nor red-shifted, so why not use the narrowest filter compatible with your
scope's focal ratio?

Clear skies,

Dennis


--- In ccd-newastro@yahoogroups.com, "tekic545" <tekic545@...> wrote:
>
> Dennis,
>
> Excellent summary. What do you see as the pros and cons of a 6 nm Ha filter vs
wider passband such as 13 nm, for a fast astrography like yours?
>
> Bob
>
> --- In ccd-newastro@yahoogroups.com, "dennis_persyk" <dpersyk@> wrote:
> >
> > Our skies are filled with nebulae. The nebulae of interest in this tutorial
are huge regions of gas – gas clouds. The nebulae I'll discuss here are called
emission nebulae. We image emission nebulae by means of the light from the
surrounding  gas cloud which is ionized by radiation from one or more nearby
stars.
> >
> > The most common emission nebulae are of the hydrogen emission type. They
emit a very narrow band of red light, and with the appropriate filter (Hydrogen
alpha, or H-a), the camera sees essentially only the nebula light, and moon
light and terrestrial light pollution is nearly completely eliminated.
> >
> > Imaging with H-a levels the imaging playing field. No matter where you are
imaging from, with an H-a filter you have the equivalent of magnitude 8 super
dark skies! Honest!
> >
> > Pros of H-a Imaging
> > • Eliminates light pollution
> > • Background is now inky black – backgrounds have a  zero or nearly zero
black point
> > • Stars are much dimmer, minimizing star bloat, chromatic aberration and
"fat" stars.
> >
> > Cons of   H-a Imaging
> > • Very little signal is passed by the filter, so imaging times have to be
fairly long – five minute subs are possible if your camera has very low readout
noise
> > • Autoguiding is probably required
> > • DLSRs without mods don't have much sensitivity to the H-a light
> >
> > Here's an example of 2 hours and 15 minutes in nine 15-minute subframes
> > http://home.att.net/~dpersyk/new.htm
> >
> > The target is NGC 281, a/k/a the "Pac Man" nebula and Sharpless 2-184. I
used a Takahashi astrograph, f/3.3 and Starlight Xpress SXV-H9 camera. The
filter was a 6 nm FWHM H-a. Most processing was done with ImagesPlus.  The false
color was added in Photoshop with Noel Carboni's actions. The Hubble employes
false color, so I don't feel like I cheated.
> >
> > I recommend H-a imaging to everyone who is plagued by sky pollution. No
longer will you have to journey to a dark site to get good images.
> >
> > Clear skies,
> >
> > Dennis Persyk
> > Igloo (Now Roll-Off) Observatory Home Page http://dpersyk.home.att.net
> > Hampshire, IL
> >
>

Thank you Dennis for the in depth Ha information. I just recently purchased one
myself
& your info here & that inspiring pacman shot really has me excited to give it a
serious run. As soon as my leg will let me (post op right now) I'll be out
there. Thanks again!

Jim
--- In ccd-newastro@yahoogroups.com, "dennis_persyk" <dpersyk@...> wrote:
>
> Our skies are filled with nebulae. The nebulae of interest in this tutorial
are huge regions of gas – gas clouds. The nebulae I'll discuss here are called
emission nebulae. We image emission nebulae by means of the light from the
surrounding  gas cloud which is ionized by radiation from one or more nearby
stars.
>
> The most common emission nebulae are of the hydrogen emission type. They emit
a very narrow band of red light, and with the appropriate filter (Hydrogen
alpha, or H-a), the camera sees essentially only the nebula light, and moon
light and terrestrial light pollution is nearly completely eliminated.
>
> Imaging with H-a levels the imaging playing field. No matter where you are
imaging from, with an H-a filter you have the equivalent of magnitude 8 super
dark skies! Honest!
>
> Pros of H-a Imaging
> • Eliminates light pollution
> • Background is now inky black – backgrounds have a  zero or nearly zero black
point
> • Stars are much dimmer, minimizing star bloat, chromatic aberration and "fat"
stars.
>
> Cons of   H-a Imaging
> • Very little signal is passed by the filter, so imaging times have to be
fairly long – five minute subs are possible if your camera has very low readout
noise
> • Autoguiding is probably required
> • DLSRs without mods don't have much sensitivity to the H-a light
>
> Here's an example of 2 hours and 15 minutes in nine 15-minute subframes
> http://home.att.net/~dpersyk/new.htm
>
> The target is NGC 281, a/k/a the "Pac Man" nebula and Sharpless 2-184. I used
a Takahashi astrograph, f/3.3 and Starlight Xpress SXV-H9 camera. The filter was
a 6 nm FWHM H-a. Most processing was done with ImagesPlus.  The false color was
added in Photoshop with Noel Carboni's actions. The Hubble employes false color,
so I don't feel like I cheated.
>
> I recommend H-a imaging to everyone who is plagued by sky pollution. No longer
will you have to journey to a dark site to get good images.
>
> Clear skies,
>
> Dennis Persyk
> Igloo (Now Roll-Off) Observatory Home Page http://dpersyk.home.att.net
> Hampshire, IL
>

Dear group



In recent days two new cameras has been introduced; the Orion Persec 8300
and the SBIG ST-8300. From before we have the QSI 583.



They all have the same sensor Kodak’s KAF-8300 sensor, but the price is
really different. The QSI starts at $3595 (then you can add filter wheel and
OAG for more $), the Orion is priced at $2500 and the SBIG at $1995. All
have regulating temp, at least QSI and SBIG have mechanical shutter (not
sure about the Orion).



What am I missing?



BR
Matts



   _____

Frεn: ccd-newastro@yahoogroups.com [mailto:ccd-newastro@yahoogroups.com] Fφr
njsgps
Skickat: den 9 november 2009 20:24
Till: ccd-newastro@yahoogroups.com
Δmne: [ccd-newastro] CCD FOV Calculator





Hi all,

I just changed to the latest (and last) version of Ron's CCD Calculator
program, and find that I can no longer 'drag' the little FOV window around
the sample images. It only ever appears 'dead centre', and can only be
'moved' by 'clicking and dragging' with the mouse - which just draws a new
window, with sizes commensurate with where the mouse 'clicked'.

Is this how the latest (v1.5.0 (c)2002) version works?

Cheers,
Niall Saunders
Clinterty Observatories
Aberdeen, SCOTLAND





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

Dennis,

Excellent summary. What do you see as the pros and cons of a 6 nm Ha filter vs
wider passband such as 13 nm, for a fast astrography like yours?

Bob

--- In ccd-newastro@yahoogroups.com, "dennis_persyk" <dpersyk@...> wrote:
>
> Our skies are filled with nebulae. The nebulae of interest in this tutorial
are huge regions of gas – gas clouds. The nebulae I'll discuss here are called
emission nebulae. We image emission nebulae by means of the light from the
surrounding  gas cloud which is ionized by radiation from one or more nearby
stars.
>
> The most common emission nebulae are of the hydrogen emission type. They emit
a very narrow band of red light, and with the appropriate filter (Hydrogen
alpha, or H-a), the camera sees essentially only the nebula light, and moon
light and terrestrial light pollution is nearly completely eliminated.
>
> Imaging with H-a levels the imaging playing field. No matter where you are
imaging from, with an H-a filter you have the equivalent of magnitude 8 super
dark skies! Honest!
>
> Pros of H-a Imaging
> • Eliminates light pollution
> • Background is now inky black – backgrounds have a  zero or nearly zero black
point
> • Stars are much dimmer, minimizing star bloat, chromatic aberration and "fat"
stars.
>
> Cons of   H-a Imaging
> • Very little signal is passed by the filter, so imaging times have to be
fairly long – five minute subs are possible if your camera has very low readout
noise
> • Autoguiding is probably required
> • DLSRs without mods don't have much sensitivity to the H-a light
>
> Here's an example of 2 hours and 15 minutes in nine 15-minute subframes
> http://home.att.net/~dpersyk/new.htm
>
> The target is NGC 281, a/k/a the "Pac Man" nebula and Sharpless 2-184. I used
a Takahashi astrograph, f/3.3 and Starlight Xpress SXV-H9 camera. The filter was
a 6 nm FWHM H-a. Most processing was done with ImagesPlus.  The false color was
added in Photoshop with Noel Carboni's actions. The Hubble employes false color,
so I don't feel like I cheated.
>
> I recommend H-a imaging to everyone who is plagued by sky pollution. No longer
will you have to journey to a dark site to get good images.
>
> Clear skies,
>
> Dennis Persyk
> Igloo (Now Roll-Off) Observatory Home Page http://dpersyk.home.att.net
> Hampshire, IL
>

Hi Mick,

Have you considered the new SBIG ST8300 at $1999?  I have an SXV-H9 which I like
alot and would recommend (maybe used?), but dont forget with the SX cameras you
have to add extra $$ for software like Maxim DL/CCD.  Not sure exactly what
addons need to be bought for the Atik line of cameras and how good their
software is that comes with the camera.  The ST8300 chip would be great with an
80mm F7 refractor as well and I believe it comes with software that is very
good.  My advice would be to add up the total costs of everything your going to
need before you make your choice.

Mike


--- In ccd-newastro@yahoogroups.com, "mick_ainge" <mick_ainge@...> wrote:
>
> Hi.
> I would like to upgrade to a new camera,and i am looking to-wards a monochrome
one.But as usual i am on a budget,so on looking around a couple of cameras have
caught my eye.
> The Starlightxpress SXVF-M7,and also the Atik 314E.
> I was wondering if anybody has any thoughts on these cameras,or indeed could
reccommed something else.
> The chosen camera would be coupled to a Celestron ED80. F7 scope.
> I would appreciate any comments.
> regards.
> Mick.
>

Thanks Bob! I appreciate your feedback.

R,


--- In ccd-newastro@yahoogroups.com, "Bob Franke" <bfranke@...> wrote:
>
> A google search shows several GSO focusers being used with RoboFocus.  Try
emailing some of those folks to see how they hooked it up.  On of the standard
RoboFocus adapters may fit your focuser.  It works great on my FSQ scope.
> http://www.robofocus.com/products.htm
>
> Bob
> http://bf-astro.com
>
>
> --- In ccd-newastro@yahoogroups.com, "ramastronomy" <ramastronomy@> wrote:
> >
> > Hi guys,
> >
> > I have an 80mm scope to which I added a GSO Crayford Focuser for Refractor
Telescopes - Dual Speed with 10:1 MicroFocuser.
> >
> > I would really appreciate any recommendations for an electric motor focuser
to work it and supported by CCDSoft. I have a mobile setup so ease of
installation and power consumption are very important.
> >
> > Best regards,
> >
> > R,
> >
>

Hi.
I would like to upgrade to a new camera,and i am looking to-wards a monochrome
one.But as usual i am on a budget,so on looking around a couple of cameras have
caught my eye.
The Starlightxpress SXVF-M7,and also the Atik 314E.
I was wondering if anybody has any thoughts on these cameras,or indeed could
reccommed something else.
The chosen camera would be coupled to a Celestron ED80. F7 scope.
I would appreciate any comments.
regards.
Mick.

Hi,

You might try putting a "want ad" for a cfw-5c on Astromart.  You might just
get lucky!

Good luck,

Don Waid
http://www.waid-observatory.com

----- Original Message -----
From: "taldan9" <alfortz9@...>
To: <ccd-newastro@yahoogroups.com>
Sent: Thursday, November 12, 2009 3:14 PM
Subject: [ccd-newastro] Colour through an SBIG 237a


>I know this question might be better at the SBIG group, but as an abject
>beginner I thought I would post it here first.
>
> I have, spending very little, acquired an SBIG 237a (at a store close-out
> of abandoned consignment items) and the SBIG efinder/focal reducer, so the
> only item missing from my perspective is the colour filter wheel and
> filters.
>
> Is the SBIG internal cfw/filters system necessary to take colour pictures
> with this camera or is there another way of doing it?  I have come across
> references to SBIG compatible CFWs, but can't get any information about
> them and the internal cfw-5c which was made by SBIG for the 237 has long
> been discontinued.
>
>
> Sheldon
>
>
>
>
>
> ------------------------------------
>
>
>
>

I know this question might be better at the SBIG group, but as an abject
beginner I thought I would post it here first.

I have, spending very little, acquired an SBIG 237a (at a store close-out of
abandoned consignment items) and the SBIG efinder/focal reducer, so the only
item missing from my perspective is the colour filter wheel and filters.

Is the SBIG internal cfw/filters system necessary to take colour pictures with
this camera or is there another way of doing it?  I have come across references
to SBIG compatible CFWs, but can't get any information about them and the
internal cfw-5c which was made by SBIG for the 237 has long been discontinued.


Sheldon

el_draco_numero_uno wrote:
> Question: Is there a fundamental reason for selecting 1.25 inch or 2
> inch filters apart from the size of the imaging chip?
>
> Seems to me it would be wiser to buy larger filters/filter wheel and
> grow into it rather than have to replace equipment at a later date.

A big factor for me in choosing 1.25-inch filters was the availability
of a mechanism that would accommodate the standard LRGB filters plus Ha,
S-II, and O-III in one wheel. I really didn't want to have to remove one
wheel and replace it with another in order to do narrowband imaging.

Furthermore, since the filters I use are parfocal, I typically focus
with the Luminance filter instead of trying to do so with a narrowband
filter, so a separate narrowband filter wheel would require me to
purchase a separate Luminance filter, since the first one would remain
with the RGB filters.

One other factor was that the 1.25-inch filters are significantly less
expensive than the larger filters.

I actually had an Optec IFW with 50mm LRGB filters, but I sold it and
bought an SBIG CFW-10 plus new 1.25-inch filters so I could incorporate
everything into one wheel.
-----
Mike

Mike Dodd
Montpelier, VA USA
http://astronomy.mdodd.com
http://NotWhatIVotedFor.com

> Just breaking in to imaging and building an equipment base.
>
> Question:
> Is there a fundamental reason for selecting 1.25 inch or 2 inch filters apart
from the size of the imaging chip?
>
> Seems to me it would be wiser to buy larger filters/filter wheel and grow into
it rather than have to replace equipment at a later date.
>
> Comments, experiences, suggestions most appreciated.
>
> Rom
The filter size 'needed', is the diagonal dimension of the chip, plus
the distance from the filter to the CCD times the focal ratio.

So if you have a f/10 scope, and the filter wheel is 25mm from the CCD,
the size required is the chip diagonal, plus 25*1/10.

This is then the minimum glass diameter that must be available, if
vignetting from the filters is not going to be a problem.

Primary 'downsides' for larger filters, are:

Cost of the filters themselves.

The wheel will need to be larger and heavier, or hold less filters.
Probably also more expensive.

You may also get a slight disadvantage, depending on how well baffled
the scope itself is, with an increased tendency to reflections causing
problems in the camera, for bright objects just outside the FOV.

However if you are likely to go to a larger chip later, then buying
larger filters in the earlier stages, is a good way to reduce the cost
of the upgrade...

Best Wishes

A google search shows several GSO focusers being used with RoboFocus.  Try
emailing some of those folks to see how they hooked it up.  On of the standard
RoboFocus adapters may fit your focuser.  It works great on my FSQ scope.
http://www.robofocus.com/products.htm

Bob
http://bf-astro.com


--- In ccd-newastro@yahoogroups.com, "ramastronomy" <ramastronomy@...> wrote:
>
> Hi guys,
>
> I have an 80mm scope to which I added a GSO Crayford Focuser for Refractor
Telescopes - Dual Speed with 10:1 MicroFocuser.
>
> I would really appreciate any recommendations for an electric motor focuser to
work it and supported by CCDSoft. I have a mobile setup so ease of installation
and power consumption are very important.
>
> Best regards,
>
> R,
>

Thanks Gerard ! That's a really nice one you have but what I'm looking for is a
electric motor to rotate the focuser I have now.

Best regards,

R,


--- In ccd-newastro@yahoogroups.com, "Pollux sterrenwacht" <Pollux@...> wrote:
>
> I'm using successfully an Optec TCF-s.
>
>
>
> Clear skies,
>
> Gerard van den Braak, Holland
>
>  <http://www.sterrenwacht.eu/> www.sterrenwacht.eu
>
> 53  05' 45.07"N  6  40' 47.12" E
>
>
>
> Van: ccd-newastro@yahoogroups.com [mailto:ccd-newastro@yahoogroups.com]
> Namens ramastronomy
> Verzonden: zondag 8 november 2009 12:03
> Aan: ccd-newastro@yahoogroups.com
> Onderwerp: [ccd-newastro] Electric Motor focuser Recommendations
>
>
>
>
>
> Hi guys,
>
> I have an 80mm scope to which I added a GSO Crayford Focuser for Refractor
> Telescopes - Dual Speed with 10:1 MicroFocuser.
>
> I would really appreciate any recommendations for an electric motor focuser
> to work it and supported by CCDSoft. I have a mobile setup so ease of
> installation and power consumption are very important.
>
> Best regards,
>
> R,
>
>
>
>
>
> [Non-text portions of this message have been removed]
>

Dennis Persyk,

Thanks for the tutorial.

  I am sitting on 6 hours of Ha SH2-171 waiting for clear nights to get RGB.  I
have Actions, but wasn't aware of the colorizing capability.

I tried the Actions feature this evening and the result looks as good as you
said it would.  Dark skies, no noise, no gradient, almost as good as your CED
214, and hours less time.

I don't think I'll now bother with RGB for this image.

Dave Bailey



To: ccd-newastro@yahoogroups.com
From: dpersyk@...
Date: Wed, 11 Nov 2009 23:14:39 +0000
Subject: [ccd-newastro] Why I Love H-a Imaging –Brief Tutorial





Our skies are filled with nebulae. The nebulae of interest in this tutorial are
huge regions of gas – gas clouds. The nebulae I'll discuss here are called
emission nebulae. We image emission nebulae by means of the light from the
surrounding gas cloud which is ionized by radiation from one or more nearby
stars.

The most common emission nebulae are of the hydrogen emission type. They emit a
very narrow band of red light, and with the appropriate filter (Hydrogen alpha,
or H-a), the camera sees essentially only the nebula light, and moon light and
terrestrial light pollution is nearly completely eliminated.

Imaging with H-a levels the imaging playing field. No matter where you are
imaging from, with an H-a filter you have the equivalent of magnitude 8 super
dark skies! Honest!

Pros of H-a Imaging
• Eliminates light pollution
• Background is now inky black – backgrounds have a zero or nearly zero black
point
• Stars are much dimmer, minimizing star bloat, chromatic aberration and "fat"
stars.

Cons of H-a Imaging
• Very little signal is passed by the filter, so imaging times have to be fairly
long – five minute subs are possible if your camera has very low readout noise
• Autoguiding is probably required
• DLSRs without mods don't have much sensitivity to the H-a light

Here's an example of 2 hours and 15 minutes in nine 15-minute subframes
http://home.att.net/~dpersyk/new.htm

The target is NGC 281, a/k/a the "Pac Man" nebula and Sharpless 2-184. I used a
Takahashi astrograph, f/3.3 and Starlight Xpress SXV-H9 camera. The filter was a
6 nm FWHM H-a. Most processing was done with ImagesPlus. The false color was
added in Photoshop with Noel Carboni's actions. The Hubble employes false color,
so I don't feel like I cheated.

I recommend H-a imaging to everyone who is plagued by sky pollution. No longer
will you have to journey to a dark site to get good images.

Clear skies,

Dennis Persyk
Igloo (Now Roll-Off) Observatory Home Page http://dpersyk.home.att.net
Hampshire, IL






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

Just breaking in to imaging and building an equipment base.

Question:
Is there a fundamental reason for selecting 1.25 inch or 2 inch filters apart
from the size of the imaging chip?

Seems to me it would be wiser to buy larger filters/filter wheel and grow into
it rather than have to replace equipment at a later date.

Comments, experiences, suggestions most appreciated.

Rom

What a wonderful discussion, Dennis.  Thanks for posting this.  I recently
ordered one of the new SBIG ST-8300's and agonized over whether to opt for C or
M. I ended up with the latter, rest assured. Your post was timely and reinforced
the feeling that I made the right decision.

Bill Shaheen
Gold Canyon, AZ
USA

--- In ccd-newastro@yahoogroups.com, "dennis_persyk" <dpersyk@...> wrote:
>
> Our skies are filled with nebulae. The nebulae of interest in this tutorial
are huge regions of gas – gas clouds. The nebulae I'll discuss here are called
emission nebulae. We image emission nebulae by means of the light from the
surrounding  gas cloud which is ionized by radiation from one or more nearby
stars.
>
> The most common emission nebulae are of the hydrogen emission type. They emit
a very narrow band of red light, and with the appropriate filter (Hydrogen
alpha, or H-a), the camera sees essentially only the nebula light, and moon
light and terrestrial light pollution is nearly completely eliminated.
>
> Imaging with H-a levels the imaging playing field. No matter where you are
imaging from, with an H-a filter you have the equivalent of magnitude 8 super
dark skies! Honest!
>
> Pros of H-a Imaging
> • Eliminates light pollution
> • Background is now inky black – backgrounds have a  zero or nearly zero black
point
> • Stars are much dimmer, minimizing star bloat, chromatic aberration and "fat"
stars.
>
> Cons of   H-a Imaging
> • Very little signal is passed by the filter, so imaging times have to be
fairly long – five minute subs are possible if your camera has very low readout
noise
> • Autoguiding is probably required
> • DLSRs without mods don't have much sensitivity to the H-a light
>
> Here's an example of 2 hours and 15 minutes in nine 15-minute subframes
> http://home.att.net/~dpersyk/new.htm
>
> The target is NGC 281, a/k/a the "Pac Man" nebula and Sharpless 2-184. I used
a Takahashi astrograph, f/3.3 and Starlight Xpress SXV-H9 camera. The filter was
a 6 nm FWHM H-a. Most processing was done with ImagesPlus.  The false color was
added in Photoshop with Noel Carboni's actions. The Hubble employes false color,
so I don't feel like I cheated.
>
> I recommend H-a imaging to everyone who is plagued by sky pollution. No longer
will you have to journey to a dark site to get good images.
>
> Clear skies,
>
> Dennis Persyk
> Igloo (Now Roll-Off) Observatory Home Page http://dpersyk.home.att.net
> Hampshire, IL
>

Our skies are filled with nebulae. The nebulae of interest in this tutorial are
huge regions of gas – gas clouds. The nebulae I'll discuss here are called
emission nebulae. We image emission nebulae by means of the light from the
surrounding  gas cloud which is ionized by radiation from one or more nearby
stars.

The most common emission nebulae are of the hydrogen emission type. They emit a
very narrow band of red light, and with the appropriate filter (Hydrogen alpha,
or H-a), the camera sees essentially only the nebula light, and moon light and
terrestrial light pollution is nearly completely eliminated.

Imaging with H-a levels the imaging playing field. No matter where you are
imaging from, with an H-a filter you have the equivalent of magnitude 8 super
dark skies! Honest!

Pros of H-a Imaging
• Eliminates light pollution
• Background is now inky black – backgrounds have a  zero or nearly zero black
point
• Stars are much dimmer, minimizing star bloat, chromatic aberration and "fat"
stars.

Cons of   H-a Imaging
• Very little signal is passed by the filter, so imaging times have to be fairly
long – five minute subs are possible if your camera has very low readout noise
• Autoguiding is probably required
• DLSRs without mods don't have much sensitivity to the H-a light

Here's an example of 2 hours and 15 minutes in nine 15-minute subframes
http://home.att.net/~dpersyk/new.htm

The target is NGC 281, a/k/a the "Pac Man" nebula and Sharpless 2-184. I used a
Takahashi astrograph, f/3.3 and Starlight Xpress SXV-H9 camera. The filter was a
6 nm FWHM H-a. Most processing was done with ImagesPlus.  The false color was
added in Photoshop with Noel Carboni's actions. The Hubble employes false color,
so I don't feel like I cheated.

I recommend H-a imaging to everyone who is plagued by sky pollution. No longer
will you have to journey to a dark site to get good images.

Clear skies,

Dennis Persyk
Igloo (Now Roll-Off) Observatory Home Page http://dpersyk.home.att.net
Hampshire, IL

Hi all.

I was wondering if anyone had seen or heard any usefull info regarding this
technology...

http://www.andor.com/learning/applications/Astronomy/

--
Regards,
Wayne
Riverland of South Australia


________________________________________________________________
sent by Webmail @ Riverland Internet

You do not need the SBIG Nikon adapter if you use the Mandel adapter. The Mandel
adapter has a Nikon bayonet mount.

--- In ccd-newastro@yahoogroups.com, Admilson <admilson_p@...> wrote:
>
> Hi,
>
> thank you for this very interesting information! In the setup shown do
> I still need the SBIG Nikon adapter or is there other one?
>
> Best
> Admilson
>
>
>
>
> ________________________________
> From: RASVP <rasvp@...>
> To: ccd-newastro@yahoogroups.com
> Sent: Sat, November 7, 2009 7:13:32 AM
> Subject: [ccd-newastro] Re: Nikon lenses for astrophotography
>
> Β 
>
>
> --- In ccd-newastro@ yahoogroups. com, "CurtisC" <calypte@ > wrote:
> >
> >
> >
> > --- In ccd-newastro@ yahoogroups. com, "RASVP" <rasvp@> wrote:
> > >
> > > I have the 180mm f/2.8 and 300mm f/4 lenses and both are very nice. I use
them stopped down (180mm at f/4, 300mm at f/5.6) with the ST-10XME and
STL-11000M. You can find images taken with them at my Web site at:
> > > http://www.alsonwongastro.com/
> >
> > You can't use these lenses with the filter wheel on the ST-10XME, can you?
>
> Yes, they can be used with the filter wheel, but you need the Mandel adapter
to be able to bring the lenses to focus:
> http://www.galaxyim ages.com/ ccdwidefield. html
>
>
>
>
>
>
>
> [Non-text portions of this message have been removed]
>