[APML] E200 and push [was: E100 and Velvia]

[Matt BenDaniel <matt@starmatt.com>]

Jose,

Many users of E200 push it. If you push E200 one stop, its ISO rating increases to 320 (but ISO numbers don't mean as much to astrophotographers as they do to regular photographers). Pushing E200 tends to brighten an under-exposed sky background to a lighter shade, yielding a better scan with some scanners. My understanding is that if you have a scanner that scans dark slides well, then you don't derive much benefit from pushing. 

Assuming your scanner scans dark slides well, pushing a film doesn't increase the resulting S/N. My usual approach is to expose the film (e.g. E200) long enough to adequately expose the unpushed film. By gathering more light, I increase S/N. Also, I like to use the entire frame but my optics vignette. In order to get the background exposure in the corners above the toe of the emulsion, I need to expose long enough. Pushing will not help much for that.

BTW in general, color negative films are not designed for pushing and do not benefit from it. However, many slides films are designed to be pushed. See the film manufacturer's web site to obtain the data sheet for each type of film that interests you.

There is no one best film for astrophotography. The film to use depends on what you're shooting, what features you want to emphasize, the focal ratio, whether you choose to hyper, etc. Even for a particular type of film, you will see conflicting stories in the APML archives, even by experienced astrophotographers. That said, I think you will find more current information about the best films for AP in the APML archives than anywhere else.

Matt

At 08:41 PM 10/21/2002 -0400, Jose Miguel Benito Huete wrote:
>Hi Robert, I am starting using E200 and as I am reading your message a question
>comes to my mind: Does it make a big different to push E200 one stop, or in
>other words do I have to always push it at least one stop? By the way I read
>your book and is very good. After reading the section on different films for
>astrophotography I don't which color film is best suited for this task
>considering both negative and slide films. Do you have the answer for this?
>Many thanks
>Jose Benito
>Madrid
>Spain

--
Matt BenDaniel
matt@starmatt.com
http://starmatt.com


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