the asa dial

Discussion in 'Photography Beginners' Forum' started by clel miller, Oct 19, 2015.

  1. clel miller

    clel miller TPF Noob!

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    It seems like it effects the light meter accordingly, but does it also do something else.?
    Thank You


     
  2. 480sparky

    480sparky Chief Free Electron Relocator Supporting Member

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    Given that it's marked ASA, I would assume you're dealing with a film camera.

    ASA is what us old geezers call ISO. You set the film speed with it so the camera knows how to adjust the meter.
     
  3. Derrel

    Derrel Mr. Rain Cloud

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    On a film camera that has an ASA dial, the dial's position might help to remind the user what film is loaded. By the time ISO got here, many 35mm film cameras had a film-type peek-a-boo window on the back, which allowed the user to literally see through a clear window to the film type and speed markings on the film. But back in the days of the ASA dial on film cameras, most 35mm camera backs had no windows. Seeing the ASA dial set to 200 for example, would have been a very good tip-off that the film was likely a 200-speed color negative film; ASA 64 would most likely have been Kodachrome 64 or Ektachrome 64; ASA 32 would likely have been a slow B&W film like Panatomic-X. ASA 125 would likely have been a medium-speed B&W film.

    As many young people might not realize, in the days of film, many cameras shot 24 to 36 exposures per YEAR, not like today's smart phones that can click off 400 pics in one weekend with the right user holding the phone...forgetting what exact kind of film was in a camera was a real issue.

    "Some" rare film cameras had so-called film type reminder dials, with small film "types" written on them, so the user could spin the dial and align the loaded film type against an index; this was later supplanted by the film box slot on the camera back of many cameras made in the 1980's. But in a word, NO, the ASA dial does not do much except to tell the camera metering system what the speed is for the loaded film (or what the desired E.I. or "Exposure Index" is for use in metering.
     
    Last edited: Oct 20, 2015
  4. clel miller

    clel miller TPF Noob!

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    OK, that is what I figured...it cranks the meter to fit the "speed" of the film.
    Never thought of the "Memo" angle :)

    Thanks Again
     
  5. wfooshee

    wfooshee No longer a newbie, moving up!

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    And once the DX film cartridges (not to be confused with Nikon DX lenses) came out, the camera could read the film speed automatically, directly from the loaded film canister, removing the need to make sure the camera was set correctly for the loaded film.

    As for memo, you couldn't beat the simplicity of sliding the film box top into the rack on the camera's back. It's the first memory card slot! :)
    [​IMG]
     
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  6. TCampbell

    TCampbell Been spending a lot of time on here!

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    If your film camera has a built-in light meter (usually visible when looking through the viewfinder) then that meter will give it's suggested exposure reading based on the ASA of the film you loaded into the camera... and that's why you set the ASA dial. So yes... changing the ASA setting on that dial will effect the meter reading. This is because film which is twice as sensitive to light means it only needs half as much light to capture the correct exposure. So if you are using 100 speed film vs. 400 speed film vs. 1000 speed film, etc. then your exposures would need to be adjusted accordingly.

    Later, the APS cameras (Advanced Photo System) had coded film canisters and the camera could retrieve the film type (including ASA/ISO) automatically. 35mm film cameras did not have coded film and you always had to set the ASA manually.
     
  7. limr

    limr Moderator Staff Member Supporting Member

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    Not before the DX coding came out, but after that, there were certainly plenty of 35mm cameras that could read coded film. You only had to set ISO manually if using bulk-loaded film or older film canisters with no coding.
     
  8. Ysarex

    Ysarex Been spending a lot of time on here!

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    :thumbyo: Yep.

    dxsensors.jpg

    Joe
     
  9. gsgary

    gsgary Been spending a lot of time on here!

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    Sometimes it gives me an orgasm when I turn it up to asa3200
     
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  10. Derrel

    Derrel Mr. Rain Cloud

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    That explains how you wore out that one camera's ASA dial...
     
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  11. sabbath999

    sabbath999 No longer a newbie, moving up!

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    That makes me chuckle a bit...

    I was a pro shooter back in the day, worked for a daily newspaper and also covered wire events...

    You could always tell a pro shooter from an amateur by looking at the back of their camera... if you saw a "box side" in it, like that, you know the guy was an an armature shooter at a news event, or a yokel. Pro shooters always put a picture of their wives or husbands or kids or sweethearts on the back.

    Why? Because body number one always had Tri-X in it, body number two (same camera, different lens) also always had Tri-X in it, and body three (a light, backup camera like a Rollie 35 had Plus-X).

    Period.

    Ever.

    Guys shooting color would do the same thing, they would load with one type of film, and shoot it. Period.

    Just another useless bit of journalistic trivia.
     
    Last edited: Oct 21, 2015
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  12. beagle100

    beagle100 Been spending a lot of time on here!

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    yes, just like they 'crank' the ISO meter to fit the light in the digital era
     

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