RE: [APML] M33 exposure results

["Greg Hartke" <ghartke@adelphia.net>]

Holy hannah! Now that you mention it, I remember reviewing your tests
because they were the only close-to-quantitative results I've seen for this
filter. I've been so busy the last couple of years that I forgot. D'oh.
Factor of 3... Jeeze, Jerry, now I'm depressed. I'm going to have to think
about that. And not screw up my polar alignment next time. I really like the
MI-250 a lot but the azimuth adjustor is a pain in the butt when it comes to
working up to a precision alignment. Elevation is easy but I spend way too
much time piddling with the azimuth.

I know, Alan. I know. I'll try it again during this bright Moon period and
see what I can do. Still, I could do an excellent drift alignment in an hour
if I didn't have to fight with the adjustor. Sheesh.

Thanks for the comments!

Regards,

Greg

-----Original Message-----
From: astro-photo-bounces@seds.org
[mailto:astro-photo-bounces@seds.org]On Behalf Of Jerry Lodriguss
Sent: Monday, October 25, 2004 1:07 AM
To: Discussion of Film Astrophotography
Subject: Re: [APML] M33 exposure results


Hi Greg,

In my experience ( http://www.astropix.com/HTML/I_ASTROP/I11/I11.HTM ) if
you want to match the sky background density, you have to expose 3x with
the IDAS LPS filter.

For example, at my site, I can expose for 15 minutes at f/2.8 with E200
without the filter, and need 45min at f/2.8 with the filter.

45 min at f/2.8 equals 360 min at f/8...

Jerry

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