Re: [APML] To Push or Not To Push

["Stuart Heggie" <Stuart.J.Heggie@sympatico.ca>]

Wei-Hao, thanks for jumping in.

Wade, I was not aware that some folks shorten their exposures BECAUSE they
are going to push the film during processing. I just figured it increased
contrast and thinned the negative thus making scanning more successful.

Stuart
----- Original Message ----- 
From: "Wei-Hao Wang" <astrophoto@gmail.com>
To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
Sent: Saturday, August 20, 2005 6:14 PM
Subject: Re: [APML] To Push or Not To Push


Hi Wade,

What you said is generally correct, if it is based on the assumption
that the photographer also decreases the exposure time when he
decides to push the film.

There won't be any loss of shadow detail if we still keep the exposure
time long.  In this case, pushing helps to increase contrast.  Indeed,
according to my signal-to-noise test, pushing even helps to improve
shadow detail a little (not much, but it does improve).  And as Jerry
pointed out in his earlier email, pushing also helps the scanning.

In short, pushing is good if we keep the exposure time long.

Cheers,
Wei-Hao


-- 
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Wei-Hao Wang  :)

Institute for Astronomy at University of Hawaii

Address:
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