Slow film BUT....

Discussion in 'Beginner Questions' started by Ricochetrider, Sep 1, 2020.

  1. My Canon AE-1 Program, Elan II, Olympus XA and a number of others all had separate exposure compensation controls. Sometimes it was just a button or lever to adjust for backlighting. Then there are other simple cameras that didn't have EC per-say but had a setting for fill flash.

    You're probably right for older film cameras when EC first started to appear. When manufactures started to incorporate more electronic and fewer mechanical controls, EC became separate. That was before digital though.
    Last edited: Sep 20, 2020
  2. Yes for old film cameras. With newer film cameras that use digital technologies they are separate like the Nikon F5, F6 etc..
  3. It doesn't matter if the cameras have separate controls or not. Film has a fixed speed, therefore a change of meter ISO and exposure compensation are one and the same thing.
  4. Yes. But the ASA value is a reminder of which film you have.

    If you decide to use a different EI value, having a separate knob keeps the reminder.

    Well, that is before the great invention that holds the box end on the back.

    Note from before built-in meters, many cameras have reminders that don't actually
    do anything other than remind.
  5. Eh, they have the same impact but they aren't the same thing.

    The Canon AE-1 was supposedly the first SLR with a microprocessor. I have the service manual for the AE-1 program which is similar. The film speed setting is a variable resister. The resistance value gets converted to a digital value and is stored in a register on the microprocessor. The light meter value is expressed as a voltage. That's converted to a digital value and stored as well. Finally the selected shutter speed is stored.

    Then microprocessor then determines the proper aperture f-stop. The service manual doesn't explain how the backlight compensation button affects this operation but I doubt it changes the resistance value that comes off the film speed setting dial. If pressed it probably does exactly what the manual says it does, - adds 1.5 stops to the calculated aperture setting.

    For cameras without an exposure compensation setting, people can use the film speed setting to compensate, but they can also compensate using shutter speed or aperture. So to me EC isn't just an altered ISO.
  6. If you use your brain instead of relying on a microprocessor, you'll see that exposure compensation has exactly the same effect as altering the ISO, whether it's a separate control or not.

    It really doesn't matter whether it's a set of markings on an ASA/ISO dial, a dumb backlight button or a separate dial, the effect is just to alter the exposure away from what's metered for the set ISO.

    Your brain is more flexible than a microprocessor program, since it can decide whether any compensation is done by changing the aperture, the shutter speed, or both.
  7. James G. Dainis

    James G. Dainis Moderator

    Using 200 ISO film, if you have the camera set to aperture priority, the program may select 1/500 sec at a designated f/11. If you want to increase exposure by one stop you can go manual and set to 1/250 sec @f/11. Or, you can change the ISO setting to 100 ISO and the camera will set automatically in aperture priority to 1/250 sec at f/11.

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