RE: [APML] star trails-8hrs on EK400 (was Provia..)

["cosmos" <cosmos@big.net.au>]

Guys..

I have not tried the above film as yet but here is my 8 hr shot on EK400 as
well as some shots of my setup.

http://www.big.net.au/~cosmos

Jim
Director: Nanango TIE-QUT Observatory
www.eese.bee.qut.edu.au/tie/sro


-----Original Message-----
From: owner-astro-photo@seds.org [mailto:owner-astro-photo@seds.org]On
Behalf Of Ulrich Beinert
Sent: Friday, January 25, 2002 10:34 PM
To: astro-photo@seds.org
Subject: AW: [APML] Provia star trails


Chris,

>I want to try a 8hr all night shot with the 20mm @ f/8 and see what
happens.
>At truly dark sites with the 100F, it looks like 1-1.5hrs at f/2.8,
>2-2.5hrs at f/4,  4hrs at f/5.6 and 8hrs at f/8 is the way to go.  This
>looks to give you a properly exposed trans to maximize the recording of
star
>colors on the film.

I have noticed that I seem to be able to expose up to 50% longer when I'm
doing star trails than when I'm tracking the camera - same film, same lens,
same f-stop. Can this be possible?

Also, if you calculate 1-1.5h at f/2.8, I'd go more for 2.5-3h at f/4, 5h at
f/5.6 and 11-12h at f/8, as I believe 100F doesn't have perfect reciprocity
characteristics. In any case, I wouldn't really do less than doubling the
exposure.

Ulrich


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