Re: 87c, Red 25, and one more...

["John Wood" <monsterjon@xxxxxxxxxxxxx>]

Setting the ASA or ISO is like telling the camera " this is the amount of
light the film needs to be exposed properly."

In the case of an automatic camera, with the ISO set at say 200, you can
change the aperture or the shutter speed for depth of field, lighting
conditions (more or less light), capturing fast movement, etc. and the
camera still knows the film is ISO 200 and gives it that much exposure for a
good image.

So when you increase the F stop (a smaller hole for the light to pass
through), the camera decreases the shutter speed (light falls on film
longer) or vice-versa and you get the same exopsure. (quantity of light that
hit the film)

With a manual camera only the light meter knows the ISO. You must then read
the F stop or the shutter speed from the meter and adjust the camera to the
meter's suggestion.

If you shoot two rolls, one at ISO 50 and the other at ISO 200, the roll
exposed at 200 has been exposed to much less light than the film exposed at
50. (lower ISO more exposure)

If you are using the same type of film (emlusion) and expose one roll  MORE
than the other, then you will have to increase the amount of development of
the LESS EXPOSED FILM, to bring out the image to an equal degree as the roll
that was exposed to more light.

More exposure, less development - less exposure, more development


-----Original Message-----
From: Luvdove6@xxxxxxx <Luvdove6@xxxxxxx>
To: infrared@xxxxx <infrared@xxxxx>
Date: Friday, October 29, 1999 2:49 AM
Subject: Re: 87c, Red 25, and one more...


>
>> Anyway, if you shoot two rolls of film at different speeds then you
>>  definitely need to adjust the development times, so no, you can't do
them
>>  at the same time (unless you are just testing).
>
>I'm still really new at all this so I still don't get how this part
works...
>if you have two rolls you shot... one at say, 50 and one at 200 and you
>metered everything.... one of the factors of exposing the film is
definitely
>ASA (EI I guess is always what you'd say for HIE) so the meter is
considering
>the light in the scene, your settings like aperture and shutter speed, and
>the ASA of the film...  so I still don't see how EXPOSURE is different if
you
>use the meter since it would change shutter speed suggestion(on manual) to
>the ASA speed you set it on.... so how are they exposed differently?
>Konica says that you should shoot HSI at ASA 12 with red 25 and ASA 32
>without a filter... so sometimes in ONE ROLL I'll switch back and forth
>depending on if I want the result to be like regular b&w (like if I'm
inside
>or whatever) and when I develop the roll it all comes out even (or seems
to,
>to me)...  do you see why I'm lost?  I know there is a difference but don't
>understand why  ;-)
>
>~Holly~
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