Nikon D70, SB-600, and Sto-Fen Omni-Bounce

Discussion in 'Nikon' started by Norm Dresner, Dec 26, 2006.

  1. Norm Dresner

    Norm Dresner Guest

    Here's my (recent) experience
    1. Macro shots
    Using the Nikon D70, any macro lens, the Nikon SB-600, and Sto-Fen
    Omni-Bounce for macro shots is producing consistently underexposed images.
    Removing the Omni-Bounce and using the strobe alone, either with or without
    the built-in diffuser, produces perfectly exposed images at every aperture
    (at lest for the range I've tried, f/5.6 - f/45). The problem appears with
    at least two different lenses, the Tamron 90mm f/2.8 and the Nikon 24-85mm
    f/2.4-8D. The underexposure is on the order of (a minimum of) 2-4 stops
    depending on magnification (subject range) and aperture setting (I almost
    always use the A-mode for macros).

    2. Moderate range (portraits and party shots)
    Using the Nikon N70, the SB-800, and the Sto-Fen Omni-Bounce produces
    consistently underexposed shots with a variety of lenses. The Nikon 18-35mm
    F3.5-4.5D, the above-mentioned lenses, and the Nikon 70-300mm f/4-5.5D are
    the most recent ones I've used. Here the underexposure ranges from 1-3
    stops depending on a large variety of factors.

    Okay, I'm guessing that something in either the camera or the strobe is
    simply using the film-subject distance to calculate the required exposure
    and not doing the more-sophisticated pre-flash to gauge subject reflectivity
    and other factors.

    A, Is my guess (more-or-less) correct?

    B. Is there some camera or strobe setting that forces it to do the right
    thing even with the diffuser in place?

    TIA
    Norm
     
    Norm Dresner, Dec 26, 2006
    #1
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  2. Norm Dresner

    Richard H. Guest

    On the flash, check that the display says TTL in the upper-left corner.
    If not, press the mode button on the flash.

    Cheers,
    Richard
     
    Richard H., Dec 26, 2006
    #2
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  3. Norm Dresner

    Norm Dresner Guest

    | Norm Dresner wrote:
    | > B. Is there some camera or strobe setting that forces it to do the
    right
    | > thing even with the diffuser in place?
    |
    | On the flash, check that the display says TTL in the upper-left corner.
    | If not, press the mode button on the flash.
    |
    | Cheers,
    | Richard

    It clearly says TTL on the flash. On the camera it shows a single
    lightening icon which AFAIK indicates normal flash operation.

    Is there any other, menu-based setting that might affect this?

    Norm
     
    Norm Dresner, Dec 26, 2006
    #3
  4. Norm Dresner

    Charlie Choc Guest

    Try tilting the flash up 45 degrees, maybe light diffused from the Sto-Fen is
    hitting the flash sensor and causing the underexposure.
     
    Charlie Choc, Dec 26, 2006
    #4
  5. Norm Dresner

    Jack Dale Guest

    I often shot with the diffuser on and the flash pointing at the
    subject. No problem with underexposure..

    Jack
     
    Jack Dale, Dec 27, 2006
    #5
  6. Norm Dresner

    Dimitris M Guest

    That happens if the reflected light enters from the eyepiece. In that case
    he needs to cover the eyepiece. Nikon provides a cover with the camera for
    that reason.

    Otherwise, in iTTL, the flash sensor of the flash should not be used.
     
    Dimitris M, Dec 27, 2006
    #6
  7. Norm Dresner

    mauerson Guest

    Please Disregard
     
    mauerson, Dec 27, 2006
    #7
  8. Norm Dresner

    AustinMN Guest

    General education mode = ON

    alt.test
    misc.test
    rec.test
    comp.test
    There are many more...

    General education mode = OFF

    Austin
     
    AustinMN, Dec 27, 2006
    #8
  9. Norm Dresner

    Richard H. Guest

    Hmmm. The diffuser would cause a light drop, but not that severe and
    metering should compensate for it (at least at short ranges). It does
    smell like something's using a calculated power (contrary to the TTL
    setting). It would seem:

    a) Light from the diffuser is somehow directly entering the meter. This
    is plausible if the flash is in auto-flash (self-metered) mode, because
    of the sensor's placement; it shouldn't be possible in TTL mode except
    with very short prime lenses. This could be tested by taping a piece of
    cardboard to the bottom of the flash head to block any direct light from
    the meters.

    b) Mere presence of the diffuser is changing behavior. There is a
    sensor on the SB-800 (and presumably the SB-600) that will zoom the
    flash head out to 14mm when a diffuser is installed. On the SB-800
    version of the Sto-Fen, there are ribs on one side to prevent triggering
    the switch. (The sensor switch is on the bottom of the flash face.)
    I'd bet on this one, though it doesn't explain what you're seeing with
    close-range macro work.

    c) The diffuser is lighting the scene differently, and matrix metering
    is keying off unexpected areas (e.g., more illuminated foreground).
    Spot-metering would be a way to test for this.

    Other thoughts...

    * If you have Auto-ISO enabled, turn it off and test with ISO 200. (So
    tests are really apples-to-apples.)

    * Try with the head head tilted up at 45 degrees.

    * There is an EV adjustment set on both the camera and the flash, and
    they're additive.

    * If exposure bracketing is on, turn it off.

    * Confirm the Flash Mode in the D70 menu is set to TTL (option 19).

    * Are you using a second flash here, or just the SB-600 on the camera?

    It's probably something so simple we're not seeing the forest for the
    trees...

    HTH,
    Richard
     
    Richard H., Dec 28, 2006
    #9
  10. Norm Dresner

    Norm Dresner Guest

    [BIG CLIP]
    | Other thoughts...
    |
    | * If you have Auto-ISO enabled, turn it off and test with ISO 200. (So
    | tests are really apples-to-apples.)
    |
    | * Try with the head head tilted up at 45 degrees.
    |
    | * There is an EV adjustment set on both the camera and the flash, and
    | they're additive.
    |
    | * If exposure bracketing is on, turn it off.
    |
    | * Confirm the Flash Mode in the D70 menu is set to TTL (option 19).
    |
    | * Are you using a second flash here, or just the SB-600 on the camera?
    |
    | It's probably something so simple we're not seeing the forest for the
    | trees...
    |
    | HTH,
    | Richard

    Auto-ISO is never on. It's almost always set to 200. Bracketing is off.
    Flash mode is definitely TTL.

    No second flash, most of the time an off-camera SB-600 connected with a
    Nikon SC-17 cord, though I've experienced this with the flash screwed onto
    the camera as well.

    A brief test confirms that tilting the flash head up 45 deg, does indeed
    help and there's a very vague recollection in the back of my fading memory
    that Sto-Fen in fact suggests doing the same thing. It's been suggested
    that with the flash set flat and the diffuser on there's too much light
    entering the flash's sensor directly. I'll try this for a while and see if
    it really does cure the problem.

    Norm
     
    Norm Dresner, Dec 28, 2006
    #10
  11. Norm Dresner

    Richard H. Guest

    Yes, StoFen does recommend pointing the head up 45 degrees. But in TTL
    mode the flash's on-board sensor shouldn't be influencing the exposure -
    it should only come into play in non-TTL auto-exposure mode.

    I suppose a quick test would be to tape a piece of cardboard to the
    bottom side of the StoFen with it pointed straight forward, to see if
    blocking it from the lens / on-board sensor has an effect.

    FWIW, I've had good results with this larger soft box:
    http://www.bhphotovideo.com/bnh/controller/home?O=3750&A=details&Q=&sku=32690&is=REG

    Regards,
    Richard
     
    Richard H., Dec 28, 2006
    #11
  12. Norm Dresner

    Savageduck Guest

    I would just confirm using a SB-800 the clip on diffuser will lock the
    flash head at 14mm and if you use the slide-out diffuser it will lock at
    17 mm. Any diffuser use will defeat TTL function.
    For general flash use, vary different angles of bounce and indirect
    placement. Using either the SB-800 or SB-600 in slave mode and
    appropriate placement will give you great creative flexibility.
    Good luck,
    Leonard
     
    Savageduck, Dec 28, 2006
    #12
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