Re: [APML]: Agfa 50 for Astrophotography

["Mike Regish" <mregish@map.com>]

Mike Regish
http://members.tripod.com/~mike534
-----Original Message-----
From: mark.kaye@sympatico.ca <mark.kaye@sympatico.ca>
To: astro-photo@nightsky.com <astro-photo@nightsky.com>
Date: Wednesday, January 28, 1998 2:56 PM
Subject: Re: [APML]: Agfa 50 for Astrophotography


>
>>I had Agfa Ultra 50 speed film in my Mamyia (for daylight shots)  and
>>decided to use up the roll and take some piggyback shots this weekend.  I
>>used the standard 80mm f/2.8 lens.  I knew that with 50 speed film
exposures
>>would need to be quite long, even at f/2.8 so I shot wide open for up to
30
>>minutes.
>
>   I do not find this too surprising.  I expose E100SW for 32 minutes at
>f2.8, so by that rule, you should expose it for an hour.

That would be true if there was no reciprocity failure or they had the same
reciprocity characteristics over an hour exposure. I think the E100 has
better reciprocity that the 50 so it would probably take a couple of hours
or more to reach what the e100 will get in 32 minutes if it even can.