Fuji SLR Camera loses 2 stop (or more) sensitivity with prolonged "on-time"

Discussion in 'Digital Photography' started by Graphic, Jul 12, 2003.

  1. Graphic

    Graphic Guest

    Has anyone else experienced this phenomenon:

    I am a convention photographer and often do on-site portraits with
    studio-type lighting.

    The last 2 times that I used my Fuji S620-Z camera (with sensor chip
    similar to the S-1 from what I understand) I had the camera turned on
    most of 6-hours then most of 10 hours on 2 separate days.

    The first time, the exposures took a sudden nose-dive towards 2-stops
    under-exposed and I blamed my lights since I did not carry my
    (ok,ok...this is only case where digital has caused me to get lazy
    and want to lighten my camera bag to the max.)

    On the second occassion I brought my light meter plus my back-up
    that I *always* carry.

    The same thing happened: sudden 2 stop decrease in sensitivity over
    initial flash meter reading of F5.6.

    ONLY this time I pulled out the flash meter--- Still reading F5.6...ok
    shoot some more photos and the histogram shows that the f2.8 photos
    are on
    the button... repeat procedure over the balance of the 200+
    portraits...EXCEPT, now F2.8 is underexposing the last 3 subjects, so
    rather than re-rig the lights I move the stand in closer for perfect
    exposures at F2.8 ...finish up the session and the flash is reading
    stop over F5.6 (remember I moved the lights in closer).

    NOTE on the lights: I am using el-cheapo screw in type e.f. that are
    ganged-up 4-lights to a fixture aimed into an umbrella. Not elegant
    but it
    always works as well as the expensive alternative *and* always
    with film exposures.

    What this means is that to get a 2-stop loss in speed, the equivalent
    of 3
    out of 4 independent flash units need to fail consistently with the
    digital camera and work perfectly with the flashmeter even when the
    are intermixed between the two. I think this rules out the e.f. as the

    Any ideas about the true cause and solution?

    Wayne Catalano
    Graphic, Jul 12, 2003
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  2. Graphic

    CSM1 Guest

    If I took a guess, I would say the electronics are heating up in the camera,
    making the sensor less sensitive to light (the ISO is drifting). Is your
    work area air conditioned?
    CSM1, Jul 12, 2003
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  3. Graphic

    Tony Wallis Guest

    Hi Cliff,

    I see you are using S2's for Wedding Work. Can I ask what flash set up you
    are using? Looking at doing my work in digital at the moment.


    Tony Wallis
    Tony Wallis, Jul 18, 2003
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