Re: [APML] question on exposure times for E200

Richard it's mostly dependant on your sky's darkness. If you have slight but noticeable skyglow near horizions I'd be afraid to go past 60 min. If it were near zenith you'd be able to go a bit longer; say 75 maybe 90. Only for the darkest skies will you be able to go 90 min at a low target like M20 at f/7.

E200 has such good reciprocity characteristics it's comparable to most 400 speed films when shooting 60 min+.

For my f/7 newt I'm usually 60 min on most exposures; especially a bright target like M20. That's for hypered 400 speed film. Only for very faint targets will I go 90 min and I'm pretty dark here. I wouldn't consider a 90 min exposure unless near zenith with my skies and setup.

Good luck and happy E200 !

Bobby Middleton

----- Original Message -----

From: Richard Crisp

To: Discussion of Film Astrophotography

Sent: Saturday, July 10, 2004 2:03 PM

Subject: [APML] question on exposure times for E200

Hi gang

I want to do some prime focus film shots tonight in the Saggittarius region using my Pentax 6x7 and some E200 film.

I am really excited about doing this.

I want to mount the camera on my AP180EDT with both the 0.75x telecompressor and the AP field flattener. That gives a focal ratio of f/6.75

My question is what exposure time should I use for something like M20?

If I got no answers from the list, I'd probably go with 45 minutes, but you folks are the experts, so I'd like to hear some other opinions.

Thanks and best regards

Richard

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