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Thread: Building an anamorphic pinhole camera...

  1. #11
    Administrator Tom Persinger's Avatar
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    Building an anamorphic pinhole camera...

    Quote Originally Posted by Ilona
    Where is the pinhole forum? (I'm sure i want to check that one! )

    http://f295.f295.org/uploads/Blah.pl

  2. #12

    Building an anamorphic pinhole camera...

    Quote Originally Posted by staft
    also, regarding cleaning your dslr, be extremely careful what method and materials you use.
    [...] and the switching between pinhole and zone plate lets more dust enter
    At the moment I'm overly careful, not cleaning at all that is... But I should really do it (or have someone do it).

    You're writing dust is a concern. Did you also use a filter with your pinhole/zoneplate assembly? I read that tip here: http://www.dennisonbertram.com/hackmaster/2005/02/digital-pinhole-lens.htm.

    I drilled a hole in a lens cap, taped a pinhole on it and put an old UV filter onto the whole thing. I hold the filter in place with some sort of white (or sometimes yellow) pasta you can use to hang posters on the wall. It's repositionable and can be removed without trace. No clue how it's called though.

  3. #13

    Building an anamorphic pinhole camera...

    i use a uv filter taped to the body cap. cleaning is fast and easy, once you get the right materials and technique down. the olympus cameras use an ultrasonic cleaning system everytime you power up, but my nikon doesn't have this.

  4. #14

    Building an anamorphic pinhole camera...

    My Canon doesn't have this feature either...

    In the meantime, I managed to develop my first roll of film ever
    It was shot with my brand new anamorphic pinhole. Well... there is close to nothing on it...

    I gave developing a second try with a new roll shot with a "normal" camera and I got images, nice and clean. So I guess the development went OK for the first film too. I must have screwed up the exposure in the pinhole camera...

    I think I'm going to try with very fast film (3200 instead of 400). Or with a film that does behave "well" with long exposures. Any advice?

  5. #15

    Building an anamorphic pinhole camera...

    When you say 'close to nothing on it' does that mean that there was some faint image there?

    I would try temporarily removing the rotating slit part (if that's possible) and trying to get some type of image on the film using it as a simple pinhole (non-anamorphic). Once you have worked out the exposure time for this you can put it back together and calculate what percentage of the total exposure time any area of film is exposed for and multiply your time to compensate.

    I would expect the exposure time (total rotation) to be between 10 to 50 times that of a simple pinhole camera depending on the width of the slit. Basically it is the ratio of the image length to the slit width multiplied by a standard pinhole exposure time to give the total rotation time.


    Steve Smith

  6. #16

    Building an anamorphic pinhole camera...

    Quote Originally Posted by tpersin
    it'd be cool if we moved this over into the pinhole forum....
    Tom, as much as you wanted this conversation moved over to the other side I think they've outvoted you

    [hr]

    Hi there, Ilona...
    if you're saying you got *almost* no image that's great because it means NO LIGHT LEAKS !!! If your developing was OK for a roll run thru a regular camera, it also means underexposure and that should be easily fixed.
    you haven't told us what f-stop you think your pinhole has or what sort of exposure times you were using under what lighting conditions... I can't help thinking you've either made a pinhole that's way too small [or it's been occluded with something] or you're exposure times are just too short for the conditions.
    I honestly can't see a need to go to anything faster than ISO 400... I'm using 100 iso film with my anamorphic pinhole and I'd love something even slower because my full sun exposure is 2 seconds and it'd be easier if I could use a longer time!
    I'm guessing that your optimum pinhole will be about 0.3mm and work out at around f/200.... give or take a bit. Under full sun conditions a pinhole somewhere near optimum should be ok with an exposure around 2sec to 4 sec for 100iso and that means under 1 second for 400iso. See what I mean?
    I'd recommend checking that your pinhole is somewhere near the proper size, make sure it isn't clagged up with some sort of rubbish and then run another test roll to see what happens.
    Good luck !!!

  7. #17

    Building an anamorphic pinhole camera...

    Hi!

    That's true about the light leaks! I didn't even think of it... That's good news!

    My camera has a pinhole of 0.29mm, measured by scanning it. The film chamber is 8cm high and the film guide (cylinder) inside the chamber has a diameter of about 6.8cm. The film itself is somewhat more than 6cm high (120). There is no slit or rotating part (far too complex for me! ).

    I used f/207 as aperture for my exposure calculations.
    I'm not sure but it may be that the pinhole is too large too get anything "sharp"... (and the exposures way too short).

    With Ilford HP5+ 400, I made exposures of 1' and 2' outdoors with light levels of 1/15 and 1/30 at f/8 400 ISO respectively. I used 3'30'' indoors with 1/8 at f/8. I tried to compensate for long exposures but apparently that was not enough.

    On the developed film, close to one edge, I have some unrecognizable distorted form, clearly making a circle (or part of). I guess that part of the film was close to the top and received more light. Not sure though. And here and there, there seems to be some very light gray "details" on the negative.

  8. #18
    Administrator Tom Persinger's Avatar
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    Building an anamorphic pinhole camera...

    Quote Originally Posted by apn
    Tom, as much as you wanted this conversation moved over to the other side I think they've outvoted you
    true true!
    sigh....

  9. #19
    500+ Posts earlj's Avatar
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    Building an anamorphic pinhole camera...

    Quote Originally Posted by Ilona
    With Ilford HP5+ 400, I made exposures of 1' and 2' outdoors with light levels of 1/15 and 1/30 at f/8 400 ISO respectively. I used 3'30'' indoors with 1/8 at f/8. I tried to compensate for long exposures but apparently that was not enough.
    If you need 1/15 at f8, then you would need 1/2 second at f22, and the Pinhole Designer chart with f208 and HP5 states 5 minutes for this setting. For the indoor shot, PD says 17 minutes. And my rule of thumb is try one exposure at the value that the chart recommends, and then try another shot using the next one down, which puts you at 17 minutes and 1 hour, respectively.

  10. #20

    Building an anamorphic pinhole camera...

    sounds like earl's got your answer... you've been caught out by a couple of stops worth of reciprocity failure [and always possible your measurement of diameter was out a fraction and that's exacerbating it?]

    don't worry about the pinhole size... if it's really about 0.29 and reasonably clean, that's so close to "ideal" that you should just leave it alone. And remember that going a lot smaller may make your images softer due to diffraction and increase your required exposure times even more. Pinhole will never be all that sharp... and the very sharp looking images you see here are often much bigger negatives than your roll film and that makes quite a difference.

    also sounds like you've had pretty dull conditions for shooting with a pinhole... perhaps picking times to take photos when there's brighter conditions would help you get your exposure times down; I assume you're using monochrome but if you ever try colour you'll also find it's heaps easier to get good colour saturation under sunny skies

    so the answer is: don't get discouraged, go have another shot at it and increase the exposure times by a couple of stops as per earl, who's a real master of these things

    too easy !!!

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