Re: [APML] Laggon & Triffid

[Herm <hermperez@worldnet.att.net>]

I bet you are getting humidity induced warping of the film.. film expands
as it absorbs moisture.. it buckles, shifts etc and the result looks just
like your picture. If it was field rotation issues it would be consistent
across the frame. It even appears as if the stars are defocused at the
center of the frame (but sharp at the corners). Try an experiment, leave a
lens off your camera and expose film to night air for 30 minutes or so..
then look at it, it will probably be buckled up from the pressure plate at
the center of the frame. It does not take much to get the effect you saw.

The solution?, do a dry air purge system.. 

"Don Spencer" <ecdon@cox.net>  wrote:

>The results? I still have alot to learn! *L* Like
>why do I have apparent field rotation even though I had 15 minutes solid
>drift in both axis(Jim Janusz and I discussed this today and came to the
>conclusion that we are not sure what is causing this). Flexure? Guiding
>through the 12" @f7.5? Who knows...

Herm
Astropics http://home.att.net/~hermperez

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