----- Original Message -----
Sent: Monday, July 28, 2003 8:08 PM
Subject: Re: [APML] New Images
Posted
When you push process, you under expose the film and compensate by over
developing it. You can rate an ISO 200 film to an EI of 400, but to get a
decent image, you have to push the film in development.
IF you do your own development, this is usually explained in how to
process the film.
I use T Max developer, I can process at 6 min at 68 deg F, get a EI of
400, or I can push the film to an EI of 3200 at 5 minutes at 75 deg F.
Note, EI is Exposure Index, more technically what you exposed the film
at. ISO (International Standards Organization) is what film is rated at by the
manufacturer. I can take an ISO 400 film and expose it at an EI of 400, 800,
3200, 4000 or 200. And develop accordingly. If I'm using black and white,
different developers do different things.
Generally you push film because you want to shorten exposure time, due to
camera shake, whatever. Or for the effect. I used to shoot rock concerts.
Tri-X at 4000 was great with a slow lens (f.4) at the time.
Generally, pushing increases the grain, lessens
contrast.
>>> keithg1@eircom.net 7/28/03 1:56:29 PM
>>>
Hello all, please excuse my ignorance, but i'm new to this
group, i've been
doing astrophotography for 1 year now -
if i am taking
a shot on the 'B' setting how can you push the film 'one
stop' - is this
the rating you set manually on dial
of
the
camera itself?
For example, if i'm using an ISO 200 Film, can i
'push' it to ISO 400 using
the dial - or am i wrong?
Thanks,
Keith......