It was the only used camera covering the FOV of the scope that was at a
price I could afford. Bought it from a guy local for about half cost
with the filters thrown in. The FLI 6303 with filters would have cost
twice and had less field. It was my first choice but never saw a used
one I could afford. I can get a friction band that will hold up in cold
so shouldn't be hard to fix. I know several engineers in the aero-space
industry. It's amazing what they can scrounge up. I sort of like such
challenges. Compared to what it took to get a fraction of the results
I'm getting now when I started in the late 50's with astro photography
this is really simple stuff if you ignore image processing. The jury
rigged stuff we used back then would blow your mind. No such thing as
off axis guiders. You built nearly everything from what you could find
in military surplus shops. Optics too often came from there. And if
you adjust for inflation the cost of what you did put together was much
much higher for a fraction the result. I'd get bored if it were too
easy. My main challenge now is learning all the various ins and outs of
processing the data. Mechanics of telescopes are easy for me but
software -- that's very foreign to me.

Rick


Richard Crisp wrote:
"Rick Johnson" wrote in message
...

Yes it uses the same mechanism. I overlaid individual flat frames each
taken after rotating to other filters then back to lum and I'd have to
rotate one by up to 2 degrees to get them to line up but the center of
rotation had to be where the center of the wheel would be, well "above"
the flat. Did the same with the other filter positions but they all line
up fine. A couple times the lum frame stopped half way between filters so
I had half lum and half something else. Can't recall which color is next
to it other than my Halpha and it wasn't that one as at that exposure time
it would have been nearly black. Next time it would be about but not
exactly in position.

I suspect cold is the problem. It was near zero (-17.5C per the uncooled
camera) when the problem first showed. Today at 10F it was doing the same
however but only about 1 degree off max. I suspect that rubber ring is
slippery right at some point at this temp. I'll take it apart and see
what I find. I could just remove it I suppose as I doubt the corrector in
the scope would defocus IR to any significant extent. Monday I'll call
SBIG and see what they have to say.



Now you are starting to see some of the reasons why I just patently reject
anything that SBIG mades after about 2003 or so.

There's no excuse for putting light sources in filter wheels which they did
with the CFW7/a and using those goofy friction drives is just being cheap
when you can use a toothed drive that never slips in my opinion as a long
time design engineer.

There's no end to the things I can point out that I think are just bad
design decisions in that STL you have but I will hold back for another day.

It still amazes me that they have the following they do. The only rational
explanation that I can see is that most people just buy what they see others
doing.

I've seen the same thing out deep sea fishing: one boat stops, then another
comes in close thinking they are catching fish. Then that attracts a third
and a fourth and a fifth and next thing you have 20 boats in the same spot
and no one is necessarily catching fish, but it is easier to stop where you
see the boats than it is to think for yourself.

Be honest Rick, why did you pick the STL versus all the other choices? Was
it because you see a lot of them in use or was it based on careful analysis
of all the relevant parameters that are important for your imaging
interests?




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Third character is a zero rather than a capital "Oh".