Roland, you may be thinking of "Improving the Thermal Properties of
Newtonian Reflectors" by Bryan Greer.  Its a two part article that appeared
in S&T May and June 2004.

John D.

>
>  --- In OAFs@yahoogroups.com, "roland_prevost" <r.prevost@...> wrote:
>
>Hi Richard! ( or anyone else who knows ),
>
>At dinner, last time, you mentioned that you thought S&T had an
>article (or perhaps two in seperate months ) on the various mods you
>could make to dobs.  Did I misunderstand you, or did you maybe say
>these articles were in very recent issues?
>
>I had S&T at home for 5 years, but stopped getting it last fall.
>Would you happen to know which articles, in which issues of S&T, you
>were thinking about?
>
>Thanks,
>Rol
>

thanks Len,  RE the chip, I looked on the ATIK site and they say its the
Sony ICX-098BL CCD chip, its the same size and pixel size (5.6 micron) as
the colour one so perhaps it is just a monochrome version. Not 100% sure on
that one.

--Piz
----- Original Message -----
From: "ldbenschop" <lbenschop@...>
To: <OAFs@yahoogroups.com>
Sent: Monday, May 31, 2004 10:15 PM
Subject: [OAFs] Re: Bevy of Lunar shots


> Piz;
> June 2003 Pg14- Letter to editor - Monogrammed Moon  By Dominique
> Dierick
> Re: CCD - Same as Toucam but mono?
>
> Len
>
> --- In OAFs@yahoogroups.com, "Mike Wirths" <mwirths@s...> wrote:
> > After looking at the image again I see the "L", cool! but which
> issue of S&T
> > was that in?
> > The chip is the same one used in the Toucam 740/840.
> >
> > thanks
> >
> > Piz
> > ----- Original Message -----
> > From: "ldbenschop" <lbenschop@h...>
> > To: <OAFs@yahoogroups.com>
> > Sent: Sunday, May 30, 2004 4:27 PM
> > Subject: [OAFs] Re: Bevy of Lunar shots
> >
> >
> > > Mike;
> > > The images look good. In the Clavius crater, there is a
> light "letter
> > > L" that was mentioned in S&T a while back. You captured it!!
> > >
> > > What CCD chip does your ATIK camera use?
> > >
> > > Len
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>

caugheyd wrote:

> But in the application in question... i.e., the cooling of a single
> object within that tube, undoubtedly the quickest way is to direct a
> turbulent stream across the object's surface.  I.e., blow.  That's
> undeniable.

Well, how about a fan sucking air out, and another fan just "stirring
the pot" within the tube, blowing at the mirror?  That way no dust is
pulled in.

Doug

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

Doug George
dgeorge@...

Diffraction Limited
Makers of Cyanogen Imaging Products
http://www.cyanogen.com

25 Conover Street
Ottawa, Ontario,
Canada, K2G 4C3

Phone:    (613) 225-2732
Fax:      (613) 225-9688

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

By George, I think he's got it!  I mean, by Doug, uhhh never mind.

A fan pulling air out the bottom (so sucking in at the top- if there's a
significant amount of dust in the air at the top of your tube ... maybe
you should be observing another night) and stirring fan(s) in front of the
mirror.  Getting enough room for a fan there may be a trick in a solid
tube dob.

The main difference between having fans sucking and blowing is that air
does have momentum.  So by blowing, you can direct where most of the air
is going to go.  Sucking it will come from the path(s) of least
resistance, and I bet that there's some weird skin effects such that the
layer right over the mirror (that we most want to get rid of) is probably
the hardest to pull off.  However, I have never taken any courses on fluid
dynamics...


Rob (for whom this discussion is largely academic)

P.S. Inspired post Dave - I can see it now - a paper entitled "The use of
a sonotube gyroscope in the stabilization of an actively cooled
astronomical telescope".  My goodness, I could go on with silly extensions
of this for hours - well, minutes at least.  CCD's with radial arrangement
of pixels that can be shifted to maintain synchronization with the main
tube...  VTOL telescopes...

"Douglas B. George" wrote:

> caugheyd wrote:
>
> > But in the application in question... i.e., the cooling of a single
> > object within that tube, undoubtedly the quickest way is to direct a
> > turbulent stream across the object's surface.  I.e., blow.  That's
> > undeniable.
>
> Well, how about a fan sucking air out, and another fan just "stirring
> the pot" within the tube, blowing at the mirror?  That way no dust is
> pulled in.
>
> Doug
>
> -----------------------------------
>
> Doug George
> dgeorge@...
>
> Diffraction Limited
> Makers of Cyanogen Imaging Products
> http://www.cyanogen.com
>
> 25 Conover Street
> Ottawa, Ontario,
> Canada, K2G 4C3
>
> Phone:    (613) 225-2732
> Fax:      (613) 225-9688
>
> -----------------------------------
>
>
>
> Yahoo! Groups Links
>
>
>
>

--
This communication is intended to be received only by the individual or
entity to whom or to which it is addressed and contains information that
is confidential. Any unauthorized use, copying, review or disclosure of
this communication is strictly prohibited. If you have received this
communication in error, please delete the message and notify the sender
by reply email. Thank you for your co-operation.

--- In OAFs@yahoogroups.com, "Douglas B. George" <dg@c...> wrote:
> Well, how about a fan sucking air out, and another fan
> just "stirring the pot" within the tube, blowing at the mirror?
> That way no dust is pulled in.

Interesting... sort of like a 'best of both worlds' approach.

Rol

Ahh!... OK... so these two articles you mention are in addition to
the January 2002 article by Alan Alder with a very similar
title "Thermal Management in Newtonian Reflectors".  Alder does
mention the work of Bryan Greer. Sounds like they all have very
similar content.

Rats!  Too bad I missed the May S&T issue, but I bet I can probably
still get a copy of the June S&T issue at Chapters.

Thanks for piping in, John.

Rol



--- In OAFs@yahoogroups.com, John Douglas <johnd@t...> wrote:
> Roland, you may be thinking of "Improving the Thermal Properties of
> Newtonian Reflectors" by Bryan Greer.  Its a two part article that
appeared
> in S&T May and June 2004.
>
> John D.
>
> >
> >  --- In OAFs@yahoogroups.com, "roland_prevost" <r.prevost@r...>
wrote:
> >
> >Hi Richard! ( or anyone else who knows ),
> >
> >At dinner, last time, you mentioned that you thought S&T had an
> >article (or perhaps two in seperate months ) on the various mods
you
> >could make to dobs.  Did I misunderstand you, or did you maybe say
> >these articles were in very recent issues?
> >
> >I had S&T at home for 5 years, but stopped getting it last fall.
> >Would you happen to know which articles, in which issues of S&T,
you
> >were thinking about?
> >
> >Thanks,
> >Rol
> >

Hi Rol,

  Guess I'll add my 2cents worth to this topic. You said that seeing that
looked like 7/10 in your 8" SCT would look like 5/10 in your 12.5" newt, I
think that if you can have both those scopes in pretty close to thermal
equalibrium, have them both nicely collimated and reasonably close in
optical quality (all hard to quantify, but hey just do your best). Then what
you are left with is the 12.5's ability to resolve both finer planetary
detail (lets use that or lunar since deepsky detail is more difficult to
concretely see) AND also finer seeing degradations (thats real atmospheric
not tube current). I'll give an example: I like to use the Jovian moons as a
yardstick for how the seeing is on a particular evening, the discs of the
Jovian moons range from around one arcsecond with Io to around 1.7
arcseconds for Ganymede (I think) on nights where the seeing is in the good
range I can see all the moons as distinct little orbs, when seeings crappy
they are like bloated little dancing balls, when its HFS seeing Ganymede can
reveal fleeting detail (seeing in the subarcsend range).
When the seeing is around the arcsecond range or just under for the best
moments your 8" may show Ganymede as a nice distinct little ball (at high
power) since the resolving power of the 8" is around .7 the 12.5 may show Io
to be less steady BUT since it can resolve finer detail (around .4) you may
get moments where you can make out some surface detail!
  This is why small apo refractors give such a pleasing esthetic view, they
can't reveal the finer detail or the finer seeing degradations, but its a
nice steady view, the larger scope will always give the more detailed view
if the seeing allows.

All of this is not to minimize the mirror cooling/tube currents discussion,
it is very important to keep the mirror close to the ambient temp. The
experiment with the box fan Attilla talked about is great for seeing which
pattern in the out of focus star image is true seeing and which is tube
current. A scope that is much warmer than ambient (say you brought it from
inside) shows the nasty "can of worms" effect where lots of squigly little
lines are writhing around, often its so bad you can't seeing the true seeing
pattern behind it, which looks like a river or stream running across the
mirror in a linear fashion. This is the time where tube currents are really
going to ruin any image and a fan will quickly get it out of this stage. I
never get that since my scopes are in the observatory and its never more
than 1-2 degrees C warmer than outside, when I know I'll be observing I open
the roof right before sunset and start running the big box fan pointed at
the back of the mirror. I also don't roll the shroud all way down so that
warmer air can escape easier. The mirror in the 18" is 1.6" thick and it
catches up quickly to ambient even if its falling quickly. The 30" takes a
lot longer as would be expected so it would benefit more from a fan esp
early in the PM when temps are falling rapidly. The type of tube current I
usually see is like when you let water gently sheet off a piece of glass so
they are like slowly moving sheets of air. This happens I think when the
mirror is within a few degrees of ambient. At this point you can see the
true seeing very easily, whether its fast or slow, the fast is sometimes too
high a frequency to detect. My own personal opinion is that when you are at
this point in the mirror cooling then the vast majority of degradation you
will see at the ep when looking at a object is true seeing degradation and
that more cooling gets mimimal effect. That being said it can't hurt any to
run the fan when you arn't looking through the ep, so it would be neat if
you could toggle a switch to run the fan or shut it down as needed. I know
Rick Singmaster is NOT a believer in using fans on the open tailgate truss
tube dobs, not sure whether I'm with him on that one I still think they are
useful early in the viewing session to get you to quality viewing quicker.
  Since yours is a closed sonotube I think that fan built in to the side of
the tube (like in the S&T article) with an exhaust duct plus a fan on the
rear would be beneficial, along with keeping it as cool as possible before
observing. Sorry about the long rambling novel :>) Hope it helped some....


cheers

Piz
----- Original Message -----
From: "roland_prevost" <r.prevost@...>
To: <OAFs@yahoogroups.com>
Sent: Monday, May 31, 2004 10:50 AM
Subject: [OAFs] Subjective Judging Seeing is OFF?


> Glad to see we've got a king of Moon Patrol thing going here.
>
> And tho' Attilla is the planetary co-ordinator at RASC ( I think? ),
> he unfortunately lacks the accompanying godly powers required to do
> anything really useful about luna, like boot it up into a higher
> orbit. ;)
>
> QUESTION: On the topic of judging SEEING at the eyepiece:
>
> I seem to be having problems judging the seeing, when using the 12.5"
> scope.  I'm so used to the views in an f/10 SCT that most of my
> SEEING-related ep reference points are from there.
>
> Is it possible that what I would call 7/10 seeing in the 8" scope ep,
> might look like 5/10 seeing in the the 12.5" ?  I collimated the
> 12.5" and got decent binary star and planetary views on other nights,
> but yesterday night -- it was waves-ville at the eyepiece.  Moon
> features were dancing around like crazy - more than I'm used to.
>
> wavelets rule!
> Rol
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>

Piz,

I greatly appreciate your and all of the opinions/advice posted on
these topics, Mike.  Tho' I have ok SCT experience, due to much
observing and imaging with an f/10 SCT-8, I'm finding that a 12.5"
f/4.8 sonotubed Newtonian is really a 'differently hued cheval' - <
as I somehow imagine PatB might put it. :) >

There seems to be much untapped knowledge/skill about these topics
floating around OAFs, so I consider myself very lucky indeed to be
the beneficiary of this accumulated experience.  I can report that it
really does help a lot with my dob learning curve.

So... thanks all,
Rol

--- In OAFs@yahoogroups.com, "Mike Wirths" <mwirths@s...> wrote:
> Hi Rol,
>
>  Guess I'll add my 2cents worth to this topic. You said that seeing
that
> looked like 7/10 in your 8" SCT would look like 5/10 in your 12.5"
newt, I
> think that if you can have both those scopes in pretty close to
thermal
> equalibrium, have them both nicely collimated and reasonably close
in
> optical quality (all hard to quantify, but hey just do your best).
Then what
> you are left with is the 12.5's ability to resolve both finer
planetary
> detail (lets use that or lunar since deepsky detail is more
difficult to
> concretely see) AND also finer seeing degradations (thats real
atmospheric
> not tube current). I'll give an example: I like to use the Jovian
moons as a
> yardstick for how the seeing is on a particular evening, the discs
of the
> Jovian moons range from around one arcsecond with Io to around 1.7
> arcseconds for Ganymede (I think) on nights where the seeing is in
the good
> range I can see all the moons as distinct little orbs, when seeings
crappy
> they are like bloated little dancing balls, when its HFS seeing
Ganymede can
> reveal fleeting detail (seeing in the subarcsend range).
> When the seeing is around the arcsecond range or just under for the
best
> moments your 8" may show Ganymede as a nice distinct little ball
(at high
> power) since the resolving power of the 8" is around .7 the 12.5
may show Io
> to be less steady BUT since it can resolve finer detail (around .4)
you may
> get moments where you can make out some surface detail!
>  This is why small apo refractors give such a pleasing esthetic
view, they
> can't reveal the finer detail or the finer seeing degradations, but
its a
> nice steady view, the larger scope will always give the more
detailed view
> if the seeing allows.
>
> All of this is not to minimize the mirror cooling/tube currents
discussion,
> it is very important to keep the mirror close to the ambient temp.
The
> experiment with the box fan Attilla talked about is great for
seeing which
> pattern in the out of focus star image is true seeing and which is
tube
> current. A scope that is much warmer than ambient (say you brought
it from
> inside) shows the nasty "can of worms" effect where lots of squigly
little
> lines are writhing around, often its so bad you can't seeing the
true seeing
> pattern behind it, which looks like a river or stream running
across the
> mirror in a linear fashion. This is the time where tube currents
are really
> going to ruin any image and a fan will quickly get it out of this
stage. I
> never get that since my scopes are in the observatory and its never
more
> than 1-2 degrees C warmer than outside, when I know I'll be
observing I open
> the roof right before sunset and start running the big box fan
pointed at
> the back of the mirror. I also don't roll the shroud all way down
so that
> warmer air can escape easier. The mirror in the 18" is 1.6" thick
and it
> catches up quickly to ambient even if its falling quickly. The 30"
takes a
> lot longer as would be expected so it would benefit more from a fan
esp
> early in the PM when temps are falling rapidly. The type of tube
current I
> usually see is like when you let water gently sheet off a piece of
glass so
> they are like slowly moving sheets of air. This happens I think
when the
> mirror is within a few degrees of ambient. At this point you can
see the
> true seeing very easily, whether its fast or slow, the fast is
sometimes too
> high a frequency to detect. My own personal opinion is that when
you are at
> this point in the mirror cooling then the vast majority of
degradation you
> will see at the ep when looking at a object is true seeing
degradation and
> that more cooling gets mimimal effect. That being said it can't
hurt any to
> run the fan when you arn't looking through the ep, so it would be
neat if
> you could toggle a switch to run the fan or shut it down as needed.
I know
> Rick Singmaster is NOT a believer in using fans on the open
tailgate truss
> tube dobs, not sure whether I'm with him on that one I still think
they are
> useful early in the viewing session to get you to quality viewing
quicker.
>  Since yours is a closed sonotube I think that fan built in to the
side of
> the tube (like in the S&T article) with an exhaust duct plus a fan
on the
> rear would be beneficial, along with keeping it as cool as possible
before
> observing. Sorry about the long rambling novel :>) Hope it helped
some....
>
>
> cheers
>
> Piz
> ----- Original Message -----
> From: "roland_prevost" <r.prevost@r...>
> To: <OAFs@yahoogroups.com>
> Sent: Monday, May 31, 2004 10:50 AM
> Subject: [OAFs] Subjective Judging Seeing is OFF?
>
>
> > Glad to see we've got a king of Moon Patrol thing going here.
> >
> > And tho' Attilla is the planetary co-ordinator at RASC ( I
think? ),
> > he unfortunately lacks the accompanying godly powers required to
do
> > anything really useful about luna, like boot it up into a higher
> > orbit. ;)
> >
> > QUESTION: On the topic of judging SEEING at the eyepiece:
> >
> > I seem to be having problems judging the seeing, when using the
12.5"
> > scope.  I'm so used to the views in an f/10 SCT that most of my
> > SEEING-related ep reference points are from there.
> >
> > Is it possible that what I would call 7/10 seeing in the 8" scope
ep,
> > might look like 5/10 seeing in the the 12.5" ?  I collimated the
> > 12.5" and got decent binary star and planetary views on other
nights,
> > but yesterday night -- it was waves-ville at the eyepiece.  Moon
> > features were dancing around like crazy - more than I'm used to.
> >
> > wavelets rule!
> > Rol
> >
> >
> >
> >
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >

Bryan Greer has contributed a fair amount to the discussion on the Big Dobs
chat group and there are some very good posts on the issue of sucking,
blowing, boundary layers, etc. in the archives of that group (some is pretty
heated actually!  Who knew?).  Also, some good info. in the Dob Fans group
(yes that's a Yahoogroup dedicated solely to the discussion of fans on
dobs!?!).  There was one link from Bryan (I believe) to a film (infrared) of
a mirror cooling in a closed tube dob without fans (various
configurations/orientations).  It turned out that vents in the top side of a
closed tube dob (just a few inches up the tube from the primary mirror cell)
were integral to removing the effects of tube currents and for speeding up
the mirror cooling process.  So if you want to avoid the possibility of
vibrations associated with fans or don't want to worry about all the
electrical stuff, vents in this location can do a great deal to mitigate
seeing effects due to tube currents and can speed up passive cooling.  Just
my 2 cents...
Cheers!
Tim Cross

There are two small (40mm?) computer fans blowing air into the bottom side of
the tube across the face of the mirror towards a series of 5 25mm holes spaced
across the top of the tube just above the face of the mirror.  Both fans are
mounted on sheets of rubber (bike tire inner tube) to prevent transmitting
vibrations to the tube.

R
>
> From: "roland_prevost" <r.prevost@...>
> Date: 2004/05/31 Mon PM 06:07:22 EDT
> To: OAFs@yahoogroups.com
> Subject: [OAFs] Re: Subjective Judging Seeing is OFF?
>
> --- In OAFs@yahoogroups.com, <rick.wagner@r...> wrote:
> > I've added the surface scrubbing fans to my 8" dob.  It stands high
> > enough off the ground that I'm not too concerned about dirt being
> > blown onto the mirror.
>
> Sounds like you have more than one fan going, Rick
>
> So what's the arrangement, if I might ask?
> Are they both ( or all ) bringing air in?
>
> Rol
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>

1

Very useful info on these Yahoo groups, Tim.

Much heated discussion on the topic of cooling fans?
An actual Dob Fans group?
Wow... guess this is a BIG topic.

So, if I understand you correctly, something like a set of 3 one-inch
diameter holes in the topside of the sonotube is what you're talking
about?  Guess one could find plugs for the holes when they aren't in
use too.

Thanks
Rol


--- In OAFs@yahoogroups.com, "Cross, Timothy" <tcross@n...> wrote:
> Bryan Greer has contributed a fair amount to the discussion on the
Big Dobs
> chat group and there are some very good posts on the issue of
sucking,
> blowing, boundary layers, etc. in the archives of that group (some
is pretty
> heated actually!  Who knew?).  Also, some good info. in the Dob
Fans group
> (yes that's a Yahoogroup dedicated solely to the discussion of fans
on
> dobs!?!).  There was one link from Bryan (I believe) to a film
(infrared) of
> a mirror cooling in a closed tube dob without fans (various
> configurations/orientations).  It turned out that vents in the top
side of a
> closed tube dob (just a few inches up the tube from the primary
mirror cell)
> were integral to removing the effects of tube currents and for
speeding up
> the mirror cooling process.  So if you want to avoid the
possibility of
> vibrations associated with fans or don't want to worry about all the
> electrical stuff, vents in this location can do a great deal to
mitigate
> seeing effects due to tube currents and can speed up passive
cooling.  Just
> my 2 cents...
> Cheers!
> Tim Cross

Rick,

The Starfinder 12.5" dob has a full 2" pyrex mirror, so cooldown is
likely to take that much longer.  The cool.exe program requires the
fan fps rating, I think, to calculate and plot probable cooldown
curves.

Since you're the only one I know who's actually installed these
mirror surface scrubbing fans, do you happen to know your small fans'
fps ratings?

Thanks,
Rol


--- In OAFs@yahoogroups.com, <rick.wagner@r...> wrote:
> There are two small (40mm?) computer fans blowing air into the
bottom side of the tube across the face of the mirror towards a
series of 5 25mm holes spaced across the top of the tube just above
the face of the mirror.  Both fans are mounted on sheets of rubber
(bike tire inner tube) to prevent transmitting vibrations to the tube.
>
> R
> >
> > From: "roland_prevost" <r.prevost@r...>
> > Date: 2004/05/31 Mon PM 06:07:22 EDT
> > To: OAFs@yahoogroups.com
> > Subject: [OAFs] Re: Subjective Judging Seeing is OFF?
> >
> > --- In OAFs@yahoogroups.com, <rick.wagner@r...> wrote:
> > > I've added the surface scrubbing fans to my 8" dob.  It stands
high
> > > enough off the ground that I'm not too concerned about dirt
being
> > > blown onto the mirror.
> >
> > Sounds like you have more than one fan going, Rick
> >
> > So what's the arrangement, if I might ask?
> > Are they both ( or all ) bringing air in?
> >
> > Rol
> >
> >
> >
> >
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
>
> 1

No idea, sorry.  I can take a look at the fans when I get back to Ottawa on the
weekend.  My 12.5" also has a full thickness mirror that will require some
significant cooling.  For the 12.5" I am thinking about putting the fans in the
sides of the mirror box or one in the side and one in the bottom so that it sets
up a circulation on the front of the mirror.  I will also add at least one fan,
possibly two to the back of the mirror.
R
>
> From: "roland_prevost" <r.prevost@...>
> Date: 2004/06/01 Tue PM 04:06:45 EDT
> To: OAFs@yahoogroups.com
> Subject: [OAFs] Re: Subjective Judging Seeing is OFF?
>
> Rick,
>
> The Starfinder 12.5" dob has a full 2" pyrex mirror, so cooldown is
> likely to take that much longer.  The cool.exe program requires the
> fan fps rating, I think, to calculate and plot probable cooldown
> curves.
>
> Since you're the only one I know who's actually installed these
> mirror surface scrubbing fans, do you happen to know your small fans'
> fps ratings?
>
> Thanks,
> Rol
>
>
> --- In OAFs@yahoogroups.com, <rick.wagner@r...> wrote:
> > There are two small (40mm?) computer fans blowing air into the
> bottom side of the tube across the face of the mirror towards a
> series of 5 25mm holes spaced across the top of the tube just above
> the face of the mirror.  Both fans are mounted on sheets of rubber
> (bike tire inner tube) to prevent transmitting vibrations to the tube.
> >
> > R
> > >
> > > From: "roland_prevost" <r.prevost@r...>
> > > Date: 2004/05/31 Mon PM 06:07:22 EDT
> > > To: OAFs@yahoogroups.com
> > > Subject: [OAFs] Re: Subjective Judging Seeing is OFF?
> > >
> > > --- In OAFs@yahoogroups.com, <rick.wagner@r...> wrote:
> > > > I've added the surface scrubbing fans to my 8" dob.  It stands
> high
> > > > enough off the ground that I'm not too concerned about dirt
> being
> > > > blown onto the mirror.
> > >
> > > Sounds like you have more than one fan going, Rick
> > >
> > > So what's the arrangement, if I might ask?
> > > Are they both ( or all ) bringing air in?
> > >
> > > Rol
> > >
> > >
> > >
> > >
> > >
> > > Yahoo! Groups Links
> > >
> > >
> > >
> > >
> > >
> > >
> >
> > 1
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>

1

Paul Weffers-Bettink came over the other night to test his MX5C
camera on my system.  He'd been experiencing that fun learning curve,
and wanted to narrow the possible variables.

Here are two images we took using his camera:

http://groups.yahoo.com/group/OAFs/files/Astrophotos/M13B.jpg
5 x 120s @ f/6.3

http://groups.yahoo.com/group/OAFs/files/Astrophotos/M57C.jpg
5 x 240s @ f/6.3

As you can see, his camera ( power supply, wires, etc. ) seem to be
working fine.

Nice camera, Paul!  ;)

Rol

Very nice!

Just for reference, Rol... what's your system?

Dave

--- In OAFs@yahoogroups.com, "roland_prevost" <r.prevost@r...> wrote:
> Paul Weffers-Bettink came over the other night to test his MX5C
> camera on my system.  He'd been experiencing that fun learning
curve,
> and wanted to narrow the possible variables.

Hi Dave,

System = as follows:

Imaging done from small b.y. observatory: "Photon's End".
Celestron DX SCT8 with the heavier mount and PEC.
Starlight Express MX5C camera, using Star2000 for autoguide.
Astroart software for image acquisition, and initial processing.
Photoshop for futher image processing.

For these 2 images just posted, we used Paul's camera & wires instead
of mine.

Rol

--- In OAFs@yahoogroups.com, "caugheyd" <caugheyd@y...> wrote:
> Very nice!
>
> Just for reference, Rol... what's your system?
>
> Dave
>
> --- In OAFs@yahoogroups.com, "roland_prevost" <r.prevost@r...>
wrote:
> > Paul Weffers-Bettink came over the other night to test his MX5C
> > camera on my system.  He'd been experiencing that fun learning
> curve,
> > and wanted to narrow the possible variables.

Hello Dave
I have the same type of a camera that Rol has - a Starlight Express
MX5C.  Rol's telescope is a fork-mounted Celestron C8 (same as what I
have), and I believe he was using a focal reducer (6.3 or 3.3).

Thanks to Rol for his help on Friday night.  I found it very
helpful.  Now if only we would get some clear skies....
Paul WB

--- In OAFs@yahoogroups.com, "caugheyd" <caugheyd@y...> wrote:
> Very nice!
>
> Just for reference, Rol... what's your system?
>
> Dave
>
> --- In OAFs@yahoogroups.com, "roland_prevost" <r.prevost@r...>
wrote:
> > Paul Weffers-Bettink came over the other night to test his MX5C
> > camera on my system.  He'd been experiencing that fun learning
> curve,
> > and wanted to narrow the possible variables.

Hi,

Now that I've bought the Astronomik OIII filter I no longer have a use for the
Lumicon which is about a year 1/2 old. Kendrick sells it new for $279 Can is
$200 sound like a fair price?
If interested let me know...oh yes its the 2" OIII.


--cheers

Piz


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

Paul and Roland,
Way to go!  Those are fanastic first images....but then again I'm
sure that the luxury of Photon's End and having Roland at the helm
ensured success!


Cheers,
Albert.

--- In OAFs@yahoogroups.com, "roland_prevost" <r.prevost@r...> wrote:
> Paul Weffers-Bettink came over the other night to test his MX5C
> camera on my system.  He'd been experiencing that fun learning
curve,
> and wanted to narrow the possible variables.
>
> Here are two images we took using his camera:
>
> http://groups.yahoo.com/group/OAFs/files/Astrophotos/M13B.jpg
> 5 x 120s @ f/6.3
>
> http://groups.yahoo.com/group/OAFs/files/Astrophotos/M57C.jpg
> 5 x 240s @ f/6.3
>
> As you can see, his camera ( power supply, wires, etc. ) seem to
be
> working fine.
>
> Nice camera, Paul!  ;)
>
> Rol

Will be at Sci & Tech Museum on morning of the Transit of Venus, if
at all clear, in case members of the general public show up there.

Rol

Not a good idea... you know how unreliable public transit is...  :-)

--- In OAFs@yahoogroups.com, "roland_prevost" <r.prevost@r...> wrote:
> Will be at Sci & Tech Museum on morning of the Transit of Venus, if
> at all clear, in case members of the general public show up there.

--- In OAFs@yahoogroups.com, "caugheyd" <caugheyd@y...> wrote:
> Not a good idea... you know how unreliable public transit is...  :-)

Yeah, and I imagine it could get even worse if I got stuck with the
wrong Transfer of Venus, right?  :)

Rol

Rol,
Does the S&T Museum have any kind of eastern horizon?

Dave - LOL!

Cheers,
Albert.


--- In OAFs@yahoogroups.com, "roland_prevost" <r.prevost@r...> wrote:
> Will be at Sci & Tech Museum on morning of the Transit of Venus,
if
> at all clear, in case members of the general public show up there.
>
> Rol

Hi Albert,

I believe the horizon is not bad from their parking lot.

Also, as an alternative, if you go far into their front lawn, then
their building would loom quite low on their horizon.

I heard they were possibly putting a solar filter on the large
refractor for the event.

Rol


--- In OAFs@yahoogroups.com, "Albert Saikaley" <albert.saikaley@c...>
wrote:
> Rol,
> Does the S&T Museum have any kind of eastern horizon?
>
> Dave - LOL!
>
> Cheers,
> Albert.
>
>
> --- In OAFs@yahoogroups.com, "roland_prevost" <r.prevost@r...>
wrote:
> > Will be at Sci & Tech Museum on morning of the Transit of Venus,
> if
> > at all clear, in case members of the general public show up there.
> >
> > Rol

> Will be at Sci & Tech Museum on morning of the Transit of Venus, if
> at all clear, in case members of the general public show up there.
>
> Rol

I'm going to Pincerest.  Since the RASC asked for scopes to appear at both
places.

-ad

Here is an image of Venus I took this afternoon:

http://www.cyberus.ca/~ec088060/images/ven2.jpg

It was fairly easy to find in the daytime using setting circles,
despite being only about 7 degrees from the sun and just a few days
from transit.

It was quite stunning visually, huge at almost 1 minute of arc, with
clearly greater than 180 degrees of crescent.  The ashen light was
also visible, although one wonders if that is an optical illusion.
The narrow slit-like planet appears to generate diffraction bands.
I tried to suppress these in the image but they still appear.

Later we spotted Venus in binoculars, just after the sun had set.  It
is still fairly easy to see, and at 10X the crescent is clearly
visible.

Hope it's clear for the transit!

-Rolf

--- In OAFs@yahoogroups.com, "roland_prevost" <r.prevost@r...> wrote:
Thanks, Roland

For anyone else who wishes to be at the museum, we are asked to be
there around 5:30 am, (although earlier is permissible) and to park
in the south lot to the side of the building.  Please let me know by
Saturday if you plan to be there (or the Pinecrest Chapters, for that
matter), so we can give an estimate of numbers of telescopes to the
media and the museum.

I am working on arranging a video system to be available at each of
the two sites, to allow more people to see it if the crowd
significantly outnumbers the telescopes.  I imagine the closing
moments will the part people will wish to see most - the rest is like
a boring slowly moving sunspot.

John

> Will be at Sci & Tech Museum on morning of the Transit of Venus, if
> at all clear, in case members of the general public show up there.
>
> Rol

Rolf;
That is an impressive image. Very sharp!
Because the cres is >180deg, must be sunlight coming through the
atmosphere/clouds.
Lets hope only Venus is cloudy for the transit!

Len

--- In OAFs@yahoogroups.com, "lindy5050" <lmeier@e...> wrote:
> Here is an image of Venus I took this afternoon:
>
> http://www.cyberus.ca/~ec088060/images/ven2.jpg
>
> It was fairly easy to find in the daytime using setting circles,
> despite being only about 7 degrees from the sun and just a few days
> from transit.
>
> It was quite stunning visually, huge at almost 1 minute of arc,
with
> clearly greater than 180 degrees of crescent.  The ashen light was
> also visible, although one wonders if that is an optical illusion.
> The narrow slit-like planet appears to generate diffraction bands.
> I tried to suppress these in the image but they still appear.
>
> Later we spotted Venus in binoculars, just after the sun had set.
It
> is still fairly easy to see, and at 10X the crescent is clearly
> visible.
>
> Hope it's clear for the transit!
>
> -Rolf

Hello Rolf.

Thanks for posting that interesting image of Venus. I had not seen
many amateur images such as that one before, so close to the sun.

Enjoyed it,

Rol


--- In OAFs@yahoogroups.com, "lindy5050" <lmeier@e...> wrote:
> Here is an image of Venus I took this afternoon:
>
> http://www.cyberus.ca/~ec088060/images/ven2.jpg
>
> It was fairly easy to find in the daytime using setting circles,
> despite being only about 7 degrees from the sun and just a few days
> from transit.
>
> It was quite stunning visually, huge at almost 1 minute of arc,
with
> clearly greater than 180 degrees of crescent.  The ashen light was
> also visible, although one wonders if that is an optical illusion.
> The narrow slit-like planet appears to generate diffraction bands.
> I tried to suppress these in the image but they still appear.
>
> Later we spotted Venus in binoculars, just after the sun had set.
It
> is still fairly easy to see, and at 10X the crescent is clearly
> visible.
>
> Hope it's clear for the transit!
>
> -Rolf

Hi John,

I am planning to attend, probably at the Museum.  I will be bringing my
scope.

For those of you who are wondering "where has Bruce BEEN!" - two things
have conspired to keep me away.  A major cross-country implementation at
work (we're half-way done), and my wife being at Western this year.  I'm
about to head off to London for the weekend, so I will miss tonight's
meeting.  (I have to set my priorities right - her birthday tomorrow
trumps my fun tonight).  Drat!  I would really appreciate it if someone
could pass on any relevant information about the transit that comes up
at the meeting.  I'll be back Monday.

I'd wish you all "clear skies", but I'll reserve that wish for Tuesday
morning.

Bruce McGlashan

> -----Original Message-----
> From: John Thompson [mailto:thompsjm@...]
> Sent: Friday, June 04, 2004 00:03
> To: OAFs@yahoogroups.com
> Subject: [OAFs] Re: Transit of Venus.
>
>
> --- In OAFs@yahoogroups.com, "roland_prevost"
> <r.prevost@r...> wrote: Thanks, Roland
>
> For anyone else who wishes to be at the museum, we are asked to be
> there around 5:30 am, (although earlier is permissible) and to park
> in the south lot to the side of the building.  Please let me know by
> Saturday if you plan to be there (or the Pinecrest Chapters, for that
> matter), so we can give an estimate of numbers of telescopes to the
> media and the museum.
>
> I am working on arranging a video system to be available at each of
> the two sites, to allow more people to see it if the crowd
> significantly outnumbers the telescopes.  I imagine the closing
> moments will the part people will wish to see most - the rest is like
> a boring slowly moving sunspot.
>
> John
>
> > Will be at Sci & Tech Museum on morning of the Transit of Venus, if
> > at all clear, in case members of the general public show up there.
> >
> > Rol
>
>
>
> ------------------------ Yahoo! Groups Sponsor
> --------------------~-->
> Yahoo! Domains - Claim yours for only $14.70
> http://us.click.yahoo.com/Z1wmxD/DREIAA/yQLSAA> /2.XolB/TM
>
>
> --------------------------------------------------------------
> ------~->
>
>
> Yahoo! Groups Links
>
>
>
>
>