A Question For anyone With A Pinhole Camera

[Mike_E]

Question: If you place a tube in front of the pinhole on your camera, does it act like a telephoto? Also, how much if any does it affect the exposure?




Just wondering,

mike

 

[windrivermaiden]

you can use a tube to cut the angle of view. but in my experience, you will end up with a round image...or a soft edged image depending on the length.

 

[compur]

Question: If you place a tube in front of the pinhole on your camera, does it act like a telephoto? Also, how much if any does it affect the exposure?




Just wondering,

mike

No, you have to increase the distance between the pinhole and the film
to get that sort of effect.

If you make a pinhole camera out of an old folding camera that has a
front standard that slides froward on a track, it can act like a "zoom" of
sorts.

Note that you also have to increase your exposure to compensate when
you do this sort of thing.

 

[Hertz van Rental]

If you know the diameter of the pinhole then using a ruler to measure it's distance from the film you can calculate the aperture. Then you can work out the exposure.
Remember that if you are using film you will probably have to adjust times for reciprocity failure if they are over a second or two.
The manufacturers data sheets will give advice on this.

 

[Dick Sanders]

Instead of placing a tube in front of your pinhole, why not make a new camera with the tube? It'll be like a telephoto lens. Just buy a mailing tube, one 4 inches in diameter and 18 or 24 inches long would work. Fit one end with a precision pinhole. Go to this site for pinhole resources:
Welcome to the Pinhole Resource
Cover the pinhole with a piece of black tape. In the darkroom, curve a piece of 4x5 film at the back end and seal up. Go out and expose by (removing black tape from pinhole) for 5 to 10 minutes. You'll need a really long exposure if the focal length is this long. Then go back into darkroom, unload, reload, etc (I've done this with a cardboard box). Then process the film. It could be very cool. But again, you'll need very long exposures for a long focal length. There are optimal pinhole sizes for various focal lengths (for the best quality pinhole photos). If that's not important, then getting a larger size pinhole will help reduce exposure times.

 

[christopher walrath]

As mentioned, the tube would simply introduce vignetting into your negative/paper. As to the exposure of the still visible portion of your subject area, it would not affect it unless, as already mentioned, you increased your 'focal' length by moving the pinhole further from your film/paper.