Re: [APML]: Re: 201xt

["David B. Toth" <ve3gyq@amsat.org>]

At 03:38 PM 9/27/96 -0400, RLECKER@aol.com wrote:
>
>In a message dated 96-09-27 00:57:26 EDT, you write:
>
><< He thinks you can take 20 second exposures to guide with. That is
>NONSENSE.
> The best guiding occurs with 1 sec. or less exposures ... I think Brad
> Wallis and Benoit Schillings showed this in graphic detail at the SBIG
> conference. If you believe you can get by with 20 sec. exposures, then go
> for the cheaper guider. But why do you think it is easier to find guide
> stars with the ST7 than the ST4? It is because : >>
>
>    I would agree with you but I think IMHO that you (and others) have taken
>what John Hoot said as: completely out of context !!!!!   Your statement
>above is NONSENSE and anybody who has experienced both cameas would

Now come on ... reread the upload about what Mr. Hoot was saying. There were
comments about 20 sec. exposures for tracking, etc.

And what were you calling nonsense? The statement about using 1 sec or
better exposures?
You would need to see Benoit's 3-D graphic analysis re guiding errors and
the effect of exposure times of the guider CCD to appreciate this. It showed
why their adaptive optics device improved seeing that was already not too bad.

And until now, it was hard to find anyone who could say that their Meade
guider worked. I am glad to hear that they seem to have worked out their
problems. But it was my understanding that the 201xt was not cooled. If that
is the case, then I cannot see how it could be guiding on stars as faint as
the ST4 does with the same exposures.

And BTW, I notice a big improvement when I use a dark frame with guiding.
Unless the guide star is VERY bright, hot pixels can confuse the algorithm
and make it hard to identify the guide star consistently. Next time I am
out, I'll try hooking up the ST4 to my laptop and actually LOOK at an image
from it to check out this impression.

Thanks for the invite to a dark site, but you really don't have a monopoly
on that. We used 3 ST4s in Australia at Ayers Rock this past April, on 8
totally clear nites (lost another one to a typhoon, and skipped the last
nite out of ten cuz we had to pack) and guided on the odd faint star. Of
course, we had a lot of brighter ones to choose from, shooting near the
Milky Way. Each of us had 4 to 6 years experience with the ST4.

I guess I am fairly skeptical of Meade claims, since their original stuff
just did not work; now I am hearing, from some users, of special algorithms
to handle non-reproduceable errors, and I have to be even more skeptical.

Dave