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Type: Posts; User: Jim Jones

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    One of the main reasons for cementing lens...

    One of the main reasons for cementing lens elements that have an exactly mating curve is to eliminate reflections. Each air-to-glass or glass-to-air transition of light in uncoated lenses causes...
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    Exposure is determined by the area of the pinhole...

    Exposure is determined by the area of the pinhole or slit.
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    Lord Rayleigh approached pinhole photography more...

    Lord Rayleigh approached pinhole photography more as a scientist than as a photographer. Photographers often arrive at slightly different formulae based on experience. For the best resolution of a...
  4. Years ago I used a White Lightning Ultra 1800 for...

    Years ago I used a White Lightning Ultra 1800 for a few 4x5 wide angle pinhole close-ups of a moving subject. The light had to be less than a foot from the subject.
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    Or an ear syringe.

    Or an ear syringe.
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    One pinhole camera can have any number of...

    One pinhole camera can have any number of pinholes. For rise, just uncover the pinhole that might give the right effect.
  7. Thanks for the heads up. Several years ago I...

    Thanks for the heads up. Several years ago I struggled with a solar pinhole camera 24 feet long made of black plastic pipe. With a few more days to work out some bugs, it might have been fairly...
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    Don, the need to invent or improvise things,...

    Don, the need to invent or improvise things, especially impossible things, isn't a sickness: it is the source much of civilization's progress.
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    Ned, the way I make very small pinholes is to use...

    Ned, the way I make very small pinholes is to use sewing pins, not needles. The head of a pin is cut off and that end of the pin is clamped in a pin vise. Perhaps it could be driven into the end of a...
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    Three guy lines might also work.

    Three guy lines might also work.
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    Many years ago I experimented with varying the...

    Many years ago I experimented with varying the user constants for IR, panchromatic, and blue sensitive film, and found that correcting the user constant according to theory did slightly improve image...
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    The mounting threads and face plate of...

    The mounting threads and face plate of traditional shutters could be removed for wider coverage. Box camera shutters traditionally had a single fixed speed between 1/25 and 1/50 of a second, and were...
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    A pinhole image is sharpest when theory says...

    A pinhole image is sharpest when theory says diffraction should begin to limit sharpness. At that point, diffraction actually sharpens the image formed by geometric optics, much like sharpening in a...
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    I haven't tried this, but an Argus C3 could take...

    I haven't tried this, but an Argus C3 could take a 26mm focal length pinhole mounted behind the shutter. Some SLRs with the mirror box removed should do as well or perhaps better. A special purpose...
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    If I was making these to sell, I'd make them in a...

    If I was making these to sell, I'd make them in a small thread mount, perhaps a Leica 39mm, and provide a ready-made adapter for larger camera mounts. This way only one machining set-up is required....
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    Original and clever tripod mount. In America...

    Original and clever tripod mount. In America 6x8x2 inch Oreo tins are sometimes available in second-hand shops. A mat board film holder can be improvised to hold 5x7 film flat inside these. Two...
  17. Thread: Glue?

    by Jim Jones
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    I've heard that artist's acrylic medium is a good...

    I've heard that artist's acrylic medium is a good glue. Its transparency can be reduced by mixing in a little black acrylic paint. Perhaps a bottle of white glue or carpenter's glue could be thus...
  18. Thread: A problem

    by Jim Jones
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    Today's small lens cameras come fairly close to...

    Today's small lens cameras come fairly close to large format film in image quality. You have to compare large original prints to really see the difference. In pinhole photography, a big increase in...
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    Press cameras usually have a rising front and...

    Press cameras usually have a rising front and often include a wire frame finder. We have to allow for parallax when using the wire frame. One way around this is to have a lens board with a cheap lens...
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    One evening I started an indoors pinhole shot on...

    One evening I started an indoors pinhole shot on film, and then metered the room light. Allowing for reciprocity failure, the sun would be up and ruining the quality of lighting before the exposure...
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    To keep the f/number constant on the film, the...

    To keep the f/number constant on the film, the film would need to be something approaching a sphere, not cylinder. This is inconvenient, but not entirely impractical with liquid emulsions applied to...
  22. There is much information on the internet about...

    There is much information on the internet about this project, for example: http://www.alternativephotography.com/wp/photographers/the-worlds-largest-pinhole-photograph.
  23. There are more efficient and less egocentric ways...

    There are more efficient and less egocentric ways to honor vanishing cultures. There have been other impressive large cameras, such as http://robroy.dyndns.info/lawrence/mammoth.html.
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    In a similar vein, when duplicating the rising...

    In a similar vein, when duplicating the rising front of a view camera in pinhole architectural shots, tilting the pinhole so its axis points about to the far edge of the film really helps in...
  25. In addition to bifocals for most use, I have one...

    In addition to bifocals for most use, I have one pair of non-bifocal glasses that focus on the distance to the computer screen. It's worth the expense for the few hours a day at the computer, or for...
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