Re: [APML] Pre-Flashing Slide Film

[Michael Cole <mrcolewa@home.com>]

Chuck,
This makes good sense.  Tony Hallas told me a while back that slide film
would be best if taken to slight sky fog, for this reason. 
I would assume that it may take a bit of experimenting to determine sky
fog level at various locations.
Mike Cole

Chuck Vaughn wrote:
> 
> I wanted to make a few observations about pre-flashing and I'm not
> tying to discourage those of you experimenting with it although
> it'll sound like it.<g>
> 
> Pre-flashing has been known for a long time but was basically given
> up on when gas hypering came along, in part because it is more difficult
> to do correctly than gas hypering. If I remember correctly, it also didn't
> show any particular advantage over gas hypering. If pre-flashing had a
> real advantage over gas hypering we'd all have setups to efficiently
> pre-flash our film. Lumicon would be selling preflash equipment instead
> of hypering tanks.
> 
> Also a slow form of pre-flashing occurs during the exposure in the form
> of sky fog. A little sky fog can actually help, especially if the film
> is a bit underhypered or the exposure is less than the sky fog limit.
> I found this out in my manually guided C14 days when I could only expose
> for 1 hour maximum. Photos at a light polluted site recorded more in the
> same time than those from 10,000 feet in the Sierra Nevada. The latter
> didn't receive the benefit of sky fog pre-flashing the film.
> 
> Chuck <aa6g@aa6g.org>
> 
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-- 
Michael Cole
Urban Imager Astrophotography Website
http://members.home.net/mrcolewa/interest.htm

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