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  1. #1
    JFB
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    Old Exposure Meter and New(er) Film Speeds

    Folks,

    I have a question regarding the ASA (ISO) ratings of today's films (B&W negative film) when used in conjunction with old exposure meters. I have a GE DW-68 serial No. R02119 which I've been using for a while now with decent results, I believe it's giving accurate readings. Tonight I read that back when my meter was built there was a safety factor of one stop built into the film ratings. I probably read that years ago and completely forgot about it.
    So should I actually be setting the exposure index number to the next smaller number on my meter, e.g. to 50 when I'm using a film rated 100 ASA? Is there any adjustment I should make for color negative film or transparencies? (I haven't shot any slides since the 1980's, but I've been thinking about getting some again.) Also just to double check-the dial on my meter reads"EXPOS INDEX" on the outer ring, so those should be ASA numbers, not the older GE film numbers?

    Pax,
    John

  2. #2
    MartinCrabtree's Avatar
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    When I use an off camera meter it's a 60+ year old Weston Master II. I found some literature from the maker on film speeds and use their recommendations w/great results. It has been reconditioned and calibrated by Quality Light Metric so I trust it and the results show that trust is warranted.

  3. #3
    AgX
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    The film speed figures have changed. Not the meters.

  4. #4
    Jim Jones's Avatar
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    The Weston Master II used Weston speed ratings developed prior to the ASA system and which were similar, but not identical, to ASA numbers. The Master III used ASA numbers. Google for Weston film speed if more information is desired.

  5. #5

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    No matter how it was calibrated in the beginning, it's changed now. I highly recommend calibrating it with a camera that you know exposes perfectly, in various lighting conditions, or using a known meter that you know is accurate. Having owned a few of these, I am pretty sure of what you will find. In good light it will give good readings (assuming the cell is still good, and you calibrate it w/ a known meter). In low interior light it will be useless. Even at factory specs, a selenium celled meter is not good for low light.

    I have a bigger, heavier meter that is more accurate inside, but in 99% of my lighting needs, the Sekonic L 188 meter below does the job, and it's so small and light you don't even know it's in your pocket, unlike your GE. It takes readily available 1.5V button batteries that last 1 to 2 years.

    http://www.ebay.com/itm/Sekonic-Auto...-/251519311687
    Last edited by momus; 05-05-2014 at 09:04 AM. Click to view previous post history.

  6. #6
    Jim Noel's Avatar
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    There are charts of equivalent rating speeds on the web. Google to find one.
    [FONT=Comic Sans MS]Films NOT Dead - Just getting fixed![/FONT]

  7. #7
    JFB
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    Gents,

    What I'm wondering is: Will I get better results if I exposed ASA 100 film using an ASA 50 setting on my (older) meter?

    When film manufacturers dropped the safety factor in their film rating did meter manufacturers alter the numbers on the meter dials?

    Pax,
    John

  8. #8
    Jim Jones's Avatar
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    Quote Originally Posted by JFB View Post
    . . . When film manufacturers dropped the safety factor in their film rating did meter manufacturers alter the numbers on the meter dials?

    Pax,
    John
    No.

  9. #9

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    Your meter should be ok use the datasheet ISO.
    Check the zero light setting is zero and your shutter speeds are normally out...
    in 61 they only changedthe mono speeds
    Trix was 200 it became 400 lots of people still use 200...

  10. #10
    Bill Burk's Avatar
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    If you rate a 100 speed film as 50 you might be giving yourself a safety factor. In that sense you can get better negatives. Slides, probably better at rated speed.

    But you might already have a safety factor working in your favor: You can see my thread regarding shutter testing where I just found my 500 setting is really giving me 1/125th second exposure.

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