From: "Tim" <tjp314@pacbell.net>
Date: November 22, 2006 12:26:35 PM MST
To: Astro_IIDC@yahoogroups.com
Subject: Re: new firewire Italian camera
Milton, David:
Well, I just ordered a Flea2 for almost a K, so I've got a vested
interest in not calling my "machine vision" cameras webcams. But even
though I've owned 4 real webcams in my time, I've never used them as
webcams. I have a problem with people watching me pick my nose while
I'm at my computer.
I've also got an SBIG ST2000XM with a CFW-10 filter wheel, a Meade DSI
Pro and a Starfish prototype I'm beta testing.
*I probably put the SBIG on the scope maybe 5 or 10 percent of the
time I image. A big part of that little use is the pain it can be to
balance on my "small" scopes (C-8, C-9.25, Megrez 80). But a second
factor is that it really comes into its own in a dark sky, and I only
get out a few times a year for that.
*The Meade DSI Pro is a turd. It works well enough for DSOs, and the
software does a decent job of stacking frames. But it's interlaced
video makes it useless for planetary imaging in all but the very best
seeing, IMHO. Also, mine has a number of clusters of hot pixels that
come and go during an imaging sequence, so the dark frames don't get
rid of them all, or if they do, they leave dark "holes" in the image.
I gave up on it for imaging, but I might fiddle with it as an
autoguider someday if I don't unload it first.
*The starfish has promise, I think. And because it uses a CMOS
sensor, it doesn't cost an appendage for a decent-size array. Can't
wait for the production model.
My favorite imagers are the Fleas by far. They're so easy to set up
(just the one cable to the laptop), and weigh so little that the only
thing I have to watch for is the cable getting caught on something
when switching from one side of the meridian to another. Since they
use Sony chips like the SX cameras (I had an HX5 once), they're very
low noise even though uncooled. I take dark frames and set the
brightness "conservatively" so as not to accumulate too much noise.
I'm still learning how to do DSO imaging after a long hiatus (nothing
serious prior to these cameras until way back with film), but the Flea
makes the experimentation process a lot of fun. My only gripe is that
the largest chips in the Point Grey cameras are half inch format, in
the Scorpions (though they do apparently have two CMOS Scorpions with
2/3" chips, I know nothing about their low light capabilities).
Problem with the dedicated astro cameras is that, for DSO imaging, you
don't need fast downloads (certainly not 1/30th second downloads for
10 minute exposures!), so the machine vision cameras really shine for
planetary. For most uses, also, you don't need a physically large chip.
I'm still dying to try my upcoming Flea2 at the focus of a 12.5"
mirror! The obstruction will be down around 10%! Put a barlow in
front of the camera, and you're rigged up for planetary imaging with
one less mirror to degrade the wavefront!
-Tim.
--- In Astro_IIDC@yahoogroups.com, "Milton Aupperle" <milton@...> wrote:
--- In Astro_IIDC@yahoogroups.com, "David Illig" <usenet@> wrote:
David wrote:
But does a webcam
with Astro IIDC count for DSO images compared to a CCD camera or
even a good DSLR? I don't think so. Pushing the envelope is fun, and
I've seen some surprisingly good DSO images from Astro IIDC and
webcams, but there is a qualifier: "Very nice, considering..."
You seem to have some really weird pre conceptions about what cameras
are and are really hung up on this "Web Cam" versus "CCD camera"
versus "DSLR", david.
Exactly what is a "CCD Camera"? Is a Meade DSI a "web camera" or a
"CCD Camera"? If I run multiple frames per second out of an SBig
camera, does that make it a "Web Cam" now instead of a "CCD Camera"?
And most of the DSLR your talking about are CMOS sensor (except for
Nikon), so does that make them "inferior" now because they aren't CCD?
Basically the feature set for a "Web Cam" depends on how much you want
to spend. If I want to spend $1500 to $2000 USD I can get a large
(1280x1024) format 16 bit FireWire Color or Mono CCD camera with <4
pixel defects which can run at frame rates as high as 200 fps and do
exposures as long as 60 minutes. And it comes in a package that fits
in my shirt pocket and doesn't require adding a complete weight system
to balance it out.
And as to "all things considered", I try to put up images that show
what people can achieve under urban light polluted skies under normal
turbulence and weather conditions and less expensive scopes and
mounts. It shows realistically what people can achieve without a lot
of effort, rather than best of breed stuff shot under perfect skies,
perfect weather, perfect high end hardware and 10+ years of experience
with image processing.
Milton Aupperle