pinhole sizes

Hello,

Have a question on pinhole size. Just started taking pinhole pictures and LOVE IT!!! Using my 4 x 5 Linhof to take black and white pictures. Was given 2 pinhole plates (are they called plates?) made out of metal. One is the size of a "pinhole" the other about the diameter of a hair shaft, (or, one is twice the diameter of the other). How would the pictures differ? I'm assuming the smaller diameter would render sharper pictures, but what else?

Thank you for your answers,

Trudee

no expert, but there's an ideal pinhole size to suit the focal length your using for the sharpest possible pics (you may not actually want that of course!). Smaller focal length, smaller pinhole required I think. There's lots of pinhole calculators around (eg www.mrpinhole.com ) that will calculate it for you.

I find the easiest way to measure the pinhole size is to use an enlarger to project the pinhole, measure the projected circle then use the magnification factor of the enlargement size to calculate the size of the pinhole.

BTW, World Pinhole Day is later this month. ( http://www.pinholeday.org/ )

welcome to pinholing. i began shooting a 4x5 pinhole in dec....now i have a hard time shooting a lens camera!
pinhole size differs for different "focal legnths". so the smaller one will be for a short focal legnth and the larger for longer legnths. i use the pinhole designer to figure all these. sorry i can not find my link right now. a .018in (.446mm) pinhole is for 100mm focal length, if that helps. you will need about a 45 sec-1 min exposure for "sunny f16". that should get you going.
also check out http://www.f295.org/Pinholeforum/forum/Blah.pl everyone on there is very supportive and helpful. enjoy.

eddie

As Nige says, there is an ideal pinhole size for each focal length, especially for maximum sharpness in the center of the image. The calculator I prefer for determining this size, or the best focal length for a given pinhole diameter, is PinholeDesigner. I've done considerable research into pinhole imaging, and prefer a user constant of 1.5 in this calculator for best on-axis sharpness. If the pinhole is significantly larger, the image has an unpleasant blur like an out-of-focus lens image. If smaller, it has a different blur due to diffraction. Wide angle pinhole cameras yield sharper images than normal or telephoto pinhole cameras. Despite this, I've used a pinhole cameras with up to a 25 foot focal length to photograph solar eclipses. The images were unsharp. When viewed at 25 feet for proper perspective, they were sharp enough. contact print from an optimum wide angle 4x5 pinhole camera viewed at arm's length will appear fairly sharp.

Images can be formed through a series of concentric circles called a zone plate. Sharpness suffers, but higher shutter speeds are possible.

Nige's suggestion of using an enlarger to determine pinhole diameter is practical. If you have a transparancy adaptor for a scanner, scanning the pinhole and counting the diameter in pixels also works. A simple calculation leads to the diameter in inches or mm, and any of the pinhole calculators gives the optimum focal length for that diameter. However, there are diverse opinions regarding the optimum focal length. The best opinion for you is the one you develop through experimentation.

Pinhole photography can be enjoyed on a primative level, as is sometimes done in elementry or middle school. However, it can also involve much study and careful construction of pinholes and cameras. One of the best on-line sorces of pinhole information is Dead Link Removed Some of the information is trivial; some very accurate.

The definitive book on pinhole photography is Pinhole Photography by Eric Renner. Eric also publishes the Pinhole Journal and holds workshops on pinhole photography. The book may be found at new or used online booksellers, or from Eric's site.