P-Sharan STD-35 and exposure

Discussion in 'Pinhole Photography' started by xtolsniffer, Jan 24, 2014.

  1. xtolsniffer

    xtolsniffer Member

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    Hi there,
    I built myself a P-Sharan STD-35 pinhole camera for a bit of fun http://www.sharan-camera.com/ but I can't quite figure out the suggested exposure times. The pinhole is stated as being 0.16mm to give F/130 for 20mm focal length which seems about right, but the suggested exposure time for ISO 100 film is 2-3 seconds for sunny conditions and 3-4 seconds for cloudy. Using the sunny F/16 rule, I would guess that F/130 should be about a half a second, so the recommended time should be about 2 stops over-exposed. The funny thing is, when I stick to the recommended times, they negatives are well exposed, but if I meter the scene and use F/130 shutter speeds (around 1/2 a second for bright sun) the negatives are underexposed. Any idea what might be going on?
    Ta!
     
  2. pen s

    pen s Member

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    I have found most exposures on pinhole to be "cut and try". After standardizing on the film (or paper), the developer, etc I make a series of test exposures and from that derive correct exposures for future use.

    Yeah, I don't understand why it doesn't conform to caculations either. Oh well.
     
  3. MattKing

    MattKing Subscriber

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    reciprocity failure?

    inaccurate size given for pinhole?
     
  4. Fixcinater

    Fixcinater Subscriber

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    I have the same kit, and ran an expired roll of BW400CN through it for a first test run. I guessed most of the exposures, and most of the failures were underexposure, with only one completely blown out frame on the roll.

    I tend towards overexposing negative film anyway, so just a bit more time than my normal guesstimate and it seems to be happy.