Re: [APML] Drift alignment problem - wedge mounted scope

["Richard Crisp" <rdcrisp@earthlink.net>]

based on what I have seen with my C14 I think Gene may be right. Is the 
drift in both RA and Dec or only in one axis? If only one, which one?

usually another good symptom if you have a ccd camera is to take an unguided 
exposure for 5 to 10 minutes and see if you have drift in the RA axis. You 
should not and if you do it is very likely to be mirror movement.


----- Original Message ----- 
From: "Gene Horr" <genehorr@houston.rr.com>
To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
Sent: Wednesday, July 27, 2005 6:30 PM
Subject: RE: [APML] Drift alignment problem - wedge mounted scope


> Could it be mirror flop?
>
> On MAPUG it has moved.  If you go to the Topical Archives page they have
> a link to subscribe on the new server.
>
> Gene Horr
>
>
>> -----Original Message-----
>> From: astro-photo-bounces@seds.org
>> [mailto:astro-photo-bounces@seds.org]On Behalf Of Bradley
>> Sent: 07/27/2005 3:38 PM
>> To: Discussion of Film Astrophotography
>> Subject: [APML] Drift alignment problem - wedge mounted scope
>>
>>
>> Afternoon, everyone;
>>
>> I seem to have a rather curious problem doing a drift alignment
>> for a Meade
>> LX200 mounted on a wedge. When adjusting the azimuth (+/- 10-15 degrees 
>> of
>> celestial equator - +/- 30 minutes of meridian) I can adjust
>> until I get no
>> observable drift in excess of 10 minutes, at -10 degrees
>> declination..but if
>> I move it up to +10 degrees declination I have a fair amount of drift
>> showing up again..less than 3-5 minutes. If I adjust to correct for
>> this..then move back to -10 degrees declination..drift is again back. 
>> Yes,
>> it changes direction..if I adjust east, for example at -10 degrees to
>> correct..then move to +10 degrees the adjustment is west to correct.
>>
>> Am I missing something? Once it's been aligned it shouldn't
>> matter whether +
>> or - declination..should it? I do know that when I did a drift alignment
>> using +20 degrees, I had a lot of field rotation showing up. Back a long
>> time ago when I aligned using approximately -15 degrees I wasn't
>> seeing any
>> field rotation.
>>
>> Right off the top of my head, I'm guessing that if the OTA isn't aligned
>> properly with the fork arms, it might cause something fluky like
>> this..maybe?
>>
>> Thanks for any input.
>>
>> Bradley
>>
>> Thorn Garden Observatory
>> http://astronomy.thorngarden.net
>>
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