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  1. #21
    Vaughn's Avatar
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    Quote Originally Posted by Ric Johnson View Post
    On my 4x5 camera, the film back is 6 inches from the pinhole (f400). No drop off at all corner to corner.
    Should only be slight less than 7" (sq root of 47) from the pinhole to the corner -- there will be some falling off of the light, but probably less than people usually burn down the corners/sides when enlarging standard negatives. Six inches should give about a normal view on 4x5.

    I did hear about a fellow who use to sell pinholes -- the edges of the holes were actually micro-filed to a knife edge. No other info, I am afraid.
    At least with LF landscape, a bad day of photography can still be a good day of exercise.

  2. #22
    richard ide's Avatar
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    If you make your own pinholes by dimpling a sheet of thin brass and use something like 600 grit sandpaper, you will get a knife edge on the hole. BTW I made an 8 x 10 pinhole camera where the film was curved in a semicircle in the box and the angle of view was close to 160 degrees. Interesting distortion as well.
    Richard

    Why are there no speaker jacks on a stereo camera?

  3. #23
    bowzart's Avatar
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    Quote Originally Posted by Vaughn View Post
    Should only be slight less than 7" (sq root of 47) from the pinhole to the corner -- there will be some falling off of the light, but probably less than people usually burn down the corners/sides when enlarging standard negatives. Six inches should give about a normal view on 4x5.

    I did hear about a fellow who use to sell pinholes -- the edges of the holes were actually micro-filed to a knife edge. No other info, I am afraid.
    Might have been me, Vaughn. I'm no longer interested in actively selling them because I don't really enjoy working for $5/hour, especially because my eyesight isn't what it used to be, but I do make one now and then for somebody.

    However, somewhere on APUG is a detailed description of my current method, which is the best yet, if anyone is crazy enough to try it.

  4. #24
    2F/2F's Avatar
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    The rule of thumb I have been taught is that the image circle is approximately 3.5x the distance from the pinhole to the film plane, so divide the diagonal of your format by 3.5 and you should have the shortest distance you can use without losing the edges completely.
    2F/2F

    "Truth and love are my law and worship. Form and conscience are my manifestation and guide. Nature and peace are my shelter and companions. Order is my attitude. Beauty and perfection are my attack."

    - Rob Tyner (1944 - 1991)

  5. #25
    2F/2F's Avatar
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    Quote Originally Posted by Ric Johnson View Post
    On my 4x5 camera, the film back is 6 inches from the pinhole (f400). No drop off at all corner to corner.
    6 inches (about 150 mm) is only slightly "widish" on 4x5 format (I call 180mm "normal" for 4x5), so I would not expect any serious falloff.

    It is not too hard to make a "center filter" dodging mask for printing pinhole pix. Expose a piece of film in the camera to an evenly-toned subject (sky, grey card, etc.). Then make a contact positive from that negative, exposed and developed to the proper density to mask ("dodge') the corners of the frame.
    Last edited by 2F/2F; 06-09-2010 at 11:54 PM. Click to view previous post history.
    2F/2F

    "Truth and love are my law and worship. Form and conscience are my manifestation and guide. Nature and peace are my shelter and companions. Order is my attitude. Beauty and perfection are my attack."

    - Rob Tyner (1944 - 1991)

  6. #26

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    Quote Originally Posted by 2F/2F View Post
    6 inches (about 150 mm) is only slightly "widish" on 4x5 format (I call 180mm "normal" for 4x5), so I would not expect any serious falloff.

    It is not too hard to make a "center filter" dodging mask for printing pinhole pix. Expose a piece of film in the camera to an evenly-toned subject (sky, grey card, etc.). Then make a contact positive from that negative, exposed and developed to the proper density to mask ("dodge') the corners of the frame.
    Clever. I like the elegance of it, especially when thinking about funky curved film planes. I've always just made a dodging tool and done it by hand.

  7. #27
    narsuitus's Avatar
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    Here are the specifications on the widest 4x5 pinhole cameras (film width = 127 mm) I have made:

    Cardboard Box (flat film plane)
    0.0126 = pinhole diameter in inches
    0.320 = pinhole diameter in mm
    2.2 = Pinhole to Film Distance in inches
    55 = Pinhole to Film Distance in mm
    132 = angle of view

    Mailing Tube (curved film plane)
    0.0126 = pinhole diameter in inches
    0.320 = pinhole diameter in mm
    2.0 = Pinhole to Film Distance in inches
    52 = Pinhole to Film Distance in mm
    140 = angle of view

    Mailing Tube (curved film plane)
    0.0102 = pinhole diameter in inches
    0.259 = pinhole diameter in mm
    2.0 = Pinhole to Film Distance in inches
    52 = Pinhole to Film Distance in mm
    140 = angle of view

    All pinholes were Laser cut in .001 inch stainless steel.

  8. #28
    BetterSense's Avatar
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    How are you making your pinholes and measuring them? I've used the soda can method in the past but I can't get over the nagging feeling that I'm leaving image quality on the table. I may spring for one of the $25 .3mm pinholes sold on the auction site, but I wish one could buy cheaper pinhole assortments.
    f/22 and be there.

  9. #29
    Lee L's Avatar
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    Quote Originally Posted by bowzart View Post
    Might have been me, Vaughn. I'm no longer interested in actively selling them because I don't really enjoy working for $5/hour, especially because my eyesight isn't what it used to be, but I do make one now and then for somebody.

    However, somewhere on APUG is a detailed description of my current method, which is the best yet, if anyone is crazy enough to try it.
    Here: http://www.apug.org/forums/995995-post35.html

  10. #30
    PhotoBob's Avatar
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    Ultra-wide with a Zero

    Quote Originally Posted by Mal View Post
    Hmmm? If the film was forced into a spherical shape rather than a semi-circular shape. The film would all be the same distance from the pinhole and you could make the focal length as short as was practical with the equipment you had. It would also give you a fisheye view, I think? I imagine the challenge is getting the film into this shape.
    I agree with Vaughn: I have a Zero Image 4x5 camera and at the shortest "focal length" of approximately 25mm (from pinhole to film) the light drop off at the corners is significant. Vignetting on a B&W image is a nice effect but it doesn't look as good with colour film... IMHO...
    Hmmm ... I have used the Zero Image 4x5 @ 25mm and find the images quite pleasing with Velvia. Although there is some light fall-off, I suspect one just has to understand how the camera makes the wide-angle exposure and plan accordingly. Not easy, but this is the wonderful thought provoking challenge of pinhole imaging, i.e., the joys of anticipation via experimentation.
    All the best, and I've really enjoyed the discussion here with you guys
    Follow the Light John 8:12
    ~~~PhotoBob

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