Reducer Corrector question

I have an 11" f/10 Celestron SCT and I am interested in getting into astro
photography. I've all but decided the Meade DSI seems like a safe place to
start. Any comments? My primary photographic goal is to capture Visual
Quality images of the 1000 brightest DSOs. Since my field of view is so
small I want to get a RC. I've seen a Celestron f/6.3, Meade f/6.3, and a
Meade f/3.3. Why is the f/3.3 not suitable for visual use? I assume there
is big time distortion around the edges. I would also like to get some lower
power for my primary use (visual observing). Budget is an issue, I can only
get one RC for now. Will the f/3.3 help the photography with wider fields
to the point that I should just save up for the f/6.3 and get it later or
will I have to throw away the edge anyway and the f/6.3 would be a better
overall value?

Thanks,

Mark Casazza
http://casazza.net
Home of the Clear Sky Alarm Clock

I've all but decided the Meade DSI seems like a safe place to
start. Any comments? My primary photographic goal is to capture Visual

Hi:

The reason the 3.3. is not advertised as being for visual use is indeed due to
vignetting a poor edge of field. But it is really just what you need. It is
really a must to reduce problems in finding, framing, exposing and tracking
with a small chip camera like the DSI. If you're going to get the DSI, IOW, the
3.3 is a must for most deep sky objects.



Peace,
Rod Mollise
Author of _Choosing and Using a Schmidt Cassegrain Telescope_
Like SCTs and MCTs?
Check-out sct-user, the mailing list for CAT fanciers!
Goto http://members.aol.com/RMOLLISE/index.html

I would get the f6.3 RC for both visual and imaging use and save up and buy
a Digital Rebel or Canon 10D (there are some real good deals on the web).
You'll get a much wider FOV with the imager (you can also use it for
ordinary digital photography). The DSI is a nice little imager for $300.00
but I think you'll be much happier with a Rebel or 10D as a "one-shot" color
imager. It also costs more.

Chuck

"Mark C" wrote in message
news:MU_Ed.11575$F97.10826@trnddc06...
I have an 11" f/10 Celestron SCT and I am interested in getting into astro
photography. I've all but decided the Meade DSI seems like a safe place
to
start. Any comments? My primary photographic goal is to capture Visual
Quality images of the 1000 brightest DSOs. Since my field of view is so
small I want to get a RC. I've seen a Celestron f/6.3, Meade f/6.3, and a
Meade f/3.3. Why is the f/3.3 not suitable for visual use? I assume
there
is big time distortion around the edges. I would also like to get some
lower
power for my primary use (visual observing). Budget is an issue, I can
only
get one RC for now. Will the f/3.3 help the photography with wider fields
to the point that I should just save up for the f/6.3 and get it later or
will I have to throw away the edge anyway and the f/6.3 would be a better
overall value?

Thanks,

Mark Casazza
http://casazza.net
Home of the Clear Sky Alarm Clock

Why is the f/3.3 not suitable for visual use? I assume there
is big time distortion around the

I have a Meade f/3.3 and have used it visually and with my Starlight Xpress
SXV-H9C camera. I'm not sure about the technical reasons but basically you see
the central obstruction as well as the sky. The view borders on being painfull
but useable for centering and framing the image. I don't think there's any
"big time distortion" around the edges of the image. There is considerable
vignetting though.

"Mark C" wrote in message
news:MU_Ed.11575$F97.10826@trnddc06...
I have an 11" f/10 Celestron SCT and I am interested in getting into
astro
photography. I've all but decided the Meade DSI seems like a safe place
to
start. Any comments? My primary photographic goal is to capture Visual
Quality images of the 1000 brightest DSOs. Since my field of view is so
small I want to get a RC. I've seen a Celestron f/6.3, Meade f/6.3, and
a
Meade f/3.3. Why is the f/3.3 not suitable for visual use? I assume
there
is big time distortion around the edges. I would also like to get some
lower
power for my primary use (visual observing). Budget is an issue, I can
only
get one RC for now. Will the f/3.3 help the photography with wider
fields
to the point that I should just save up for the f/6.3 and get it later
or
will I have to throw away the edge anyway and the f/6.3 would be a
better
overall value?
There are two reason 'areas' for the F*.33, not being suggested for visual
use. The first is the spacing required. A reducer, gives it's design
reduction, at a particular spacing to the focal plane. The F*.63 reducers
(the two units from Meade, and Celestron, come from the same
manufacturer), has enough focal length, that it is just 'in spec', used on
the rear port of the scope, with a 1.25" diagonal, and eyepiece. With the
*.33 reducer placed in the same configuration, you are approaching the
focal length of the reducer, and get massively more reduction than you
should, and normally find yourself showing the CO of the scope as well...
The second part is the useable field. The *.33 reducer, only just gives
acceptable results across a focal plane, perhaps 1/4 to 1/3" diagonally.
As such it was designed for CCD's, the same sort of size as you are
talking about. If you attach most eyepieces, you will see very sigificant
coma to the edges of the field, and vignetting.
For your CCD, the *.33, is really the best choice. As a 'general' tool,
for use with larger chips, and eyepieces, the *.63, is instead the way to
go.

Best Wishes

Uncle Bob:
The Canon is a fantastic little piece of work.
I am so happy I bought one, I might go out and buy another one to take a
picture of it.

Forgive me, but I used a Nikon D100 to take a picture of my 20D.
http://www.davidillig.com/ast-20dmounted.shtml.

Davoud

--
usenet *at* davidillig dawt com

Yes, I am sure the Rebel or 10D would be better. A member of the local
society has one. But I'm not sure I will be doing enough imaging to spend
the money. If I end up doing lots of imaging, I'm sure I'll buy one next
year.

Mark Casazza
http://casazza.net
Home of the Clear Sky Alarm Clock

"Chuck" wrote in message
...
I would get the f6.3 RC for both visual and imaging use and save up and
buy
a Digital Rebel or Canon 10D (there are some real good deals on the web).
You'll get a much wider FOV with the imager (you can also use it for
ordinary digital photography). The DSI is a nice little imager for
$300.00
but I think you'll be much happier with a Rebel or 10D as a "one-shot"
color
imager. It also costs more.

Chuck

I've all but decided the Meade DSI seems like a safe place to
start. Any comments? My primary photographic goal is to capture Visual

Hi:

The reason the 3.3. is not advertised as being for visual use is indeed
due to
vignetting a poor edge of field. But it is really just what you need. It
is
really a must to reduce problems in finding, framing, exposing and
tracking
with a small chip camera like the DSI. If you're going to get the DSI,
IOW, the
3.3 is a must for most deep sky objects.



Peace,
Rod

Thanks Rod. Based on your comment and others I am wondering about the f/6.3
and the possibility of imaging through an eyepiece. I have an adapter that
will hold an EP and the camera. I suspect I will get more use out of the
f/6.3 unless I find myself doing a lot of imaging. At that point I will be
getting a better camera etc.

Mark Casazza
http://casazza.net
Home of the Clear Sky Alarm Clock