Are Newtonians Good for Widefield CCD Imaging?

Seems like all the posted images taken with the 35mm frame imagers use high
end APO's.

But has anyone tried to do so with a more modest newtonian reflector?
With or without a Paracorr?

Glen

But has anyone tried to do so with a more modest newtonian reflector?
With or without a Paracorr?

Glen

I use an Orion Space Probe 130ST for imaging. This scope is 130mm F5 Newt with
a 29% central obstruction.

There are several issues that make it less than ideal.

First, is that a 35mm camera will not come to focus... I use either a Cool
Pix 4500 mounted afocally and a 32mm plossl or a cooled CCD camera similar to a
ST-237, definitely not widefield.

The Coolpix provides a FOV something like 2 x 1.3 degrees not exactly wide
field but not so bad either.

Second is the issue of the fully illuminated FOV. With a Smaller newt, this is
a problem because there is a trade off between the size of the central
obstruction and the fully illuminated Field of view.

With this scope the 75% illuminated FOV is about 2 degrees. This may not be a
problem with the Coolpix because of the small chip size.

So the question is: Have I been able to take some photos with this that I have
been happy with?

Most certainly. Is this scope or any small Newt going to provide the sort of
widefield views one gets with top notch refractor?

I don't think so.

jon

http://www.tisd.net/~jng3/stars/

Now there's some fine ccd imaging with a 6" f/5 reflector!

Best regards,
Bil
"Glen Baker" wrote in message
...
Seems like all the posted images taken with the 35mm frame imagers use
high
end APO's.

But has anyone tried to do so with a more modest newtonian reflector?
With or without a Paracorr?

Glen

Oh darn... now you've done it... I am just going to have to get the
MX5C/Ultima 8-PEC with F6.3 R/C back into service...

Thanks for the link Bill. That is one serious inspiration to those of us
with this modest camera.

Stephen


"Bill Becker" wrote in message
...
http://www.tisd.net/~jng3/stars/

Now there's some fine ccd imaging with a 6" f/5 reflector!

Best regards,
Bil
"Glen Baker" wrote in message
...
Seems like all the posted images taken with the 35mm frame imagers use
high
end APO's.

But has anyone tried to do so with a more modest newtonian reflector?
With or without a Paracorr?

Glen

There have been people who take widefield pictures with Newtonians and lot of
them end of gravitating to the Takahashi Epsilon Series of Newts these are 6,
8, 10 and 12 inches of aperture they are around F3.3 have field corrective lens
and sport secondary obstructions approaching 40% I had a Epsilon 210 for a
short while. Never got to use it mush ended up selling it to pay off some bills
that got piled up. One of my Astro Buddies has a Epsilon 250 and its huge.

Another friend of mine who recentlu moved to Ohio carreer move change has a
8 inch Mak Newt that has been optimized for Astro-Photography it sports a 4
inch Flat and a corrective field lens as well it was custom made by Peter
Ceravolo some years ago. This scope may end up for sale.

There is another person I know who has a 9.25 schimdt Camera at F2.5 has a
fairly decent field this one has just recently come up for sale. This scope was
also custom made

The problem with common visual Newtonians that I find is that the optics
need to be better polished to reduce scatter and some sort of custom field
flatner needs to put together the parrachor is not really intended for
Astro-Photography it is primarily a visual accessory

Clear Skies
Dwight L Bogan

I'm really interested in the Canon Rebel.
Is this able to deliver 16 bit luminosity readings like a good CCD camera?

I know Takahashi makes fine instruments but I might as well invest in a APO
if I were to spend that much.

Glen

Unless a Newtonian has been built or modified specifically for this purpose,
they are next to useless. They are fantastic for visual use, and can be
modified for photography, but have a limited overall FOV photographically. Or
so I've been told from several sources.
Clear, Dark, Steady Skies!
(And considerate neighbors!!!)

Glen Baker wrote in message ...
I'm really interested in the Canon Rebel.
Is this able to deliver 16 bit luminosity readings like a good CCD camera?

No, it doesn't (besides, it's far away (below) in performance from a
typical CCD camera for astro use). It's a 12 bit (per channel) device,
AFAIK.


I know Takahashi makes fine instruments but I might as well invest in a APO
if I were to spend that much.

Not as fast nor as well corrected for wide field views/pics. And yes,
newtons can be made to cover the 35mm format provided you have a coma
corrector (if the newton is faster than f/7) in place.

Andrea T.

Which typical CCD camera offers photographic resolution anywhere near the
price of the Rebel($900 US)?

Stacking seems to make acceptable images.

The ST-7 has too few pixels for my taste. The ST-2000 is even more at
$2995.


Glen

No, it doesn't (besides, it's far away (below) in performance from a
typical CCD camera for astro use). It's a 12 bit (per channel) device,
AFAIK.

No, it doesn't (besides, it's far away (below) in performance from a
typical CCD camera for astro use). It's a 12 bit (per channel) device,
AFAIK.


Which typical CCD camera offers photographic resolution anywhere near the
price of the Rebel($900 US)?

Performance in a astro-camera has more to do with noise levels than with the
number of pixels. And then too, there is the dynamic range.

Stacking seems to make acceptable images.

Its certainly one way to go but of course one can stack cooled CCD images and
go even deeper....

The ST-7 has too few pixels for my taste. The ST-2000 is even more at
$2995.

Have you tried these or any other cooled CCD camera? In my limited
experience, they are pretty amazing.

jon isaacs