Re: DSI Pro II Images?
- From: Steve Sherman <smsherm@xxxxxxxxxxxxx>
- Date: Tue, 18 Apr 2006 19:13:23 -0400
Stephen Paul wrote:
Doink wrote:
Has anyone used the Meade DSI Pro II? I'd like to see some B/W images from
it...
Still weighing the 300D Stephen Paul has done great stuff with that camera
and the price is good.
Doink
Well, I'm not really deserving of accolade. Truth is, I've been lucky a
few times when everything was working in my favor. At least so it seems
given the rarity with which I'm actually able to get out and image. :-)
One other non-obvious advantage of the DSLR (and any large chip array),
is that it covers more area on the sky, which means that you don't have
to be dead on with your aim. 3000x2000 at 2 arcseconds per pixel covers
a lot of sky (50min x 33min). Even at 1 arcsecond you are still
covering 25 minutes x 17 minutes of arc.
"Close enough" works with DSLR's. :-)
As I understand it, the real downside to the DSLR is the pixel well
depth (or charge capacity). The DSLR doesn't have the depth of charge
that a CCD has, and that means the camera doesn't have as good a
dynamic range for extracting fine contrast differences out of targets.
For example, the core of a globular cluster will saturate pixels,
before the dim outer stars have been recorded.
With a CCD, this is less of a problem, as the depth of charge of the
pixel is "deeper" (doesn't saturate as fast).
Here's what I might do if I had it to do over again....
Buy a _professionally_ modded DSLR with the standard 18-55mm lens ($700
used) and add a good 100-400mm zoom ($1400), both with an end filter
for UV/IR for day use ($80x2). Then I'd get a self-guided 765x512 pixel
CCD camera (ST7 or MX916 for $1000??) that I could use as an autoguider
for imaging with the DSLR using the camera lenses, as well as using a
600mm focal length 80ED ($400). I could then also do CCD imaging at
1280mm and 2032mm with a C8 ($550 no-XLT) and an F6.3 R/C ($100).
Not positive, but you might even get away with an AS-CG-5GT mount
($600), although I'd probably shoot for the GM-8 (non-Gemini; $1100) as
a minimum.
For the C8, you don't need a guide scope as the CCD is self guiding.
For the DSLR, you need a camera piggy back kit for the 80ED and a way
to connect the CCD to the 100-400 zoom for auto-guiding when using the
80ED for imaging. (Of course you use the 80ED as a guide scope for DSLR
imaging.)
That would pretty much cover it.
:-)
-Stephen
You are assuming that all DSLR do not have a CCD imager.
In fact, most DSLR have a CCD imager. Canon is
the big CMOS guy. Most others, like Nikon, have CCD.
Steve
.
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