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  1. #11
    SMBooth's Avatar
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    That's pinhole! If you make the hole bigger it will soften the image. But try it,you may like it.

  2. #12

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    Quote Originally Posted by markbau View Post
    Is there any reason not to make a bigger hole so that the exposures are shorter or am I missing something? f161, according to the sunny 16 rule, would be approx 2 second exposure meaning I'm in reciprocity land even on a sunny day!
    Hi Mark,

    What film is that? ISO 100 film will need 1 sec. exposure. There's not much point in using high resolution ISO 25/ 50 or 100 film; just use ISO 400 film when shooting pinhole. With 400 film, your exposures will be around 1/4 sec. (@ F161) in bright / sunny days. Since your format is (relatively) small (I do 4x5 pinholes), you'd better opt for the sharpest possible result. Pinhole doesn't look that nice to me for smaller formats, but that's highly subjective...

    Regards,
    Loris.

  3. #13

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    I've noticed that the person selling one on Ebay indicates a 75mm focal length.

  4. #14
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    Quote Originally Posted by markbau View Post
    Is there any reason not to make a bigger hole so that the exposures are shorter or am I missing something? f161, according to the sunny 16 rule, would be approx 2 second exposure meaning I'm in reciprocity land even on a sunny day!


    Exposures can go from 2 seconds to XXX minutes on a pinhole camera. Don't sweat over "long" exposures. Who cares about reciprocity. A pinhole photograph will not be perfect, but it will be a very nice artistic variation on the bog standard photography of SLRs, digital, and anything else you can think of. Be it noted that the nature of pinhole cameras is to record the image in time — often a lot of it. DaVinci took 5 weeks to record the Sun's movement in the Tower of Winds using the first known pinhole!

  5. #15
    Poisson Du Jour's Avatar
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    Quote Originally Posted by markbau View Post
    I was allowing for the lens cap. My measurement wasn't exact as I couldn't get the mirror up as I have a roll of film in it. I never have figured out how to fire the shutter without film in the camera even though I've owned it for 20 years, just never needed to!
    The best and safest way is to load a dud roll into the 67, or try two empty spools loaded. A slender penny-sized tool is used to tweak the winding mechanism to allow 'dry firing', however, Pentax has never been too keen on dry firing: the camera was not designed for it; that is to say, it will only cock the shutter and initiate the winding mechanism when film is loaded. It is also too easy to damage the shutter curtain or mar the mirror. And old roll of film in it will be a much safer way to examine things.

  6. #16
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    To dry fire open the back and then use your finger to roll the film counter past 1 or 2 hold it there and close the back, wind and fire all you like. A dud roll will not stop you being a klutz a breaking sometime though. If you just want to check the film flange distance open the back and measure the distance between the pressure plate and camera back then measure the flange to back and subtract that measurement, won't need to stick thing into the camera unless its for pleasure

  7. #17
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    Hi,
    Just on the difference between drilling a cap and poking a piece of aluminium foil, the generally-accepted theory is that foil is best, because thickness matters a lot. Including the sanding, that's designed to make it as thin as possible. Here is a bit of an explanation of how it affects angle-of-coverage. I thought there was another effect on other things but my google is failing me, or maybe that's the only problem.

    I'm thinking of my lens caps, they're generally 1-2mm thick, way too much for a real hole. If you weren't already going to, I'd drill a 10mm or so hole in the lenscap and attach a piece of foil or otherwise to that...

    (Or take the lazy way out and buy a Skink Pinhole kit like I did)
    An awful lot of electrons were terribly inconvenienced in the making of this post.

    f/64 and be there.

  8. #18

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    I will be drilling into very thin brass (not sure what thickness yet) and then drilling a wide flat bottom impression into the body cap (that has a small hole drilled through it) that the drilled brass will slip into, this way I can have several different size pinholes to experiment with. Still working on how to hold the brass plate into the body cap


    Quote Originally Posted by Dr Croubie View Post
    Hi,
    Just on the difference between drilling a cap and poking a piece of aluminium foil, the generally-accepted theory is that foil is best, because thickness matters a lot. Including the sanding, that's designed to make it as thin as possible. Here is a bit of an explanation of how it affects angle-of-coverage. I thought there was another effect on other things but my google is failing me, or maybe that's the only problem.

    I'm thinking of my lens caps, they're generally 1-2mm thick, way too much for a real hole. If you weren't already going to, I'd drill a 10mm or so hole in the lenscap and attach a piece of foil or otherwise to that...

    (Or take the lazy way out and buy a Skink Pinhole kit like I did)
    It is said that we remember the important things, if true, why photograph? I forget, so I photograph.

  9. #19
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    One way to have interchangeable pinholes and zone plates in a body cap or in a home-made camera is to mount a filter with the glass removed in the cap or camera. Another filter ring can retain a disc with the pinhole or zone plate. A third filter with opaque material substituted for the glass works as a shutter for longer exposures. A handful of old filters all the same size can be cheap online or in some camera stores.

    I usually use .002" brass shim stock for pinholes. Thinner shim stock is more difficult to work with. Thicker shim stock is unnecessarily thick. For critical results, the pinhole diameter is important. I'd use about .010" for a 55mm focal length, based on testing for optimum central sharpness. A slight increase in diameter will favor off-axis sharpness. Making the pinhole large enough to significantly reduce exposure will yield awfully unsharp images.

  10. #20
    edp
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    Fuji Acros has excellent reciprocity characteristics, making it great for pinholes.

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