Re: [APML]: M20 through DeepSky

["Andrea Ricciardi" <mc7624@mclink.it>]

----
From: Chuck Vaughn <aa6g@aa6g.org>
To: astro-photo@nightsky.com
Date: Friday, August 29, 1997 8:17 PM
Subject: Re: [APML]: M20 through DeepSky

>
>Philip Perkins wrote:
>
>>Andrea, thanks - you noticed the same thing as Jerry - the DS shot
should
>>have been exposed much longer to be a valid comparison. From a close
>>examination of the neg I believe the unfiltered shot was optimally
exposed,
>>which means the DS shot should have had about 4 hrs!  But as you say, 2x
>>would have been close enough to be a reasonable comparison.
>
>The filter factor doesn't mean you *have* to expose longer but that the
filter
>*allows* you to expose longer by reducing light pollution. There would be
>no point in using a filter if you had to expose longer to get the same as
>in white light.
>

Has someone exposed with the DS 4x getting the same density of un
unfiltered shot? I've tried 2x and I've get very good results and almost
the same sky fog under quite good skys. Maybe it's a matter of films used?

Andrea.