Pinhole Questiongreenspun.com : LUSENET : Large format photography : One Thread
I've got an old B&J press camera with no lens, no rangefinder and no lensboard. The best thing I can say about what is left of it is that it is light tight. I'd like to try pinhole photography. I have two very specific questions:
1. If I want try it out as a wide angle camera, say in the 65 mm to 90 mm range, what sizes of pinholes would I use? I assume getting a sheet of brass and drilling (or punching a hole) in it would work, with a little filing a zone VI lensboard would fit the front standard and I could apply the brass with the hole in it to the front of the lens board.
2. How far do I move the pinhole from the film in order to have the image properly focussed? (Or is it "focused?" We'd all look a lot smarter if this site had spell check.) My starting guess would be the same distance as the focal length of the pinhole but I really have no idea.
3. I lied, I have a third question. Using TRI-X on front-lit subjects what is a ball park exposure for something like this? I was going to start off in the one minute range.
As always, thanks for your responses.
-- Kevin Crisp (KRCrisp@aol.com), August 05, 2001
The "optomal" pinhole diameter varies with focal length, so marking the focal lengths on the camera base would make it easier to judge. There are many resources and FAQs online for determining pinhole size/focal lenths - here is a good place to start -
The best formula for size is : 0.0073 * SQR (focal length in inches) SQR stands for square root. For metric system the formula becomes: Pinhole diameter = 0.03679 * SQR (focal length) where diameter and focal length are in millimeters.
Here are some other places to check out:
Lenox Laser sells very precisely laser-drilled pinholes in .0005" stainless sheet, and they come mounted on a 3/4" disc. They also have some calculation info.
Good luck, and have fun.
-- Matt O. (email@example.com), August 05, 2001.
Kevin: You might want to contact the folks at the Pinhole Resource, http://www.pinholeresource.com/ They have micro-drilled pinholes that come with a focal lenght chart.
-- Ron McElroy (firstname.lastname@example.org), August 05, 2001.
-- David Stein (DFStein@aol.com), August 06, 2001.
You can make pretty decent pinholes out of brass shim stock. I have instructions for one method on my site at http://unblinkingeye.com/Articles/Pinhole/pinhole.html. I find that if I can get the f-stop near f/256 I can keep my sunlit exposures to about one second, though f-stops of 512 or more are perfectly feasible.
-- Ed Buffaloe (email@example.com), August 06, 2001.
I spent about 25 bucks on laser drilled pinholes at Calumet and don't regret it at all. You get pinholes for a large variety of focal lengths and an information sheet which gives optimum pinhole/focal length and exposure information.
Exposure will vary with the size of the pinhole. You don't have to use the "optimum" pinhole for any given focal length -- it just makes a sharper image. You might not want a sharp image.
I actually found Tri-X a little too fast for sunny days as I prefer an exposure of about a minute or so since my shutters are usually funky. I use Arista 125 generally and even APX 25 in my 6x6 pinhole camera.
One side note. I have read many comments about how poorly pinhole negatives enlarge. I have not found this to be so at all. I have shot many pinholes with a 6x6 camera that enlarge to 8x10 very beautifully.
-- Erik Ryberg (firstname.lastname@example.org), August 06, 2001.
I placed a pinhole on my cambo 4x5 to play with while I was waiting for the lens I ordered to come in. You can just take a piece of pie tin and a sewing needle and make a very tiny hole. Tape it on the lens board being sure to seal out all light except for the pinhole itself and you're done. Focus is always there so you don't have to worry about it. The closer th pinhole is to the film, the more the image looks like a wide-angle. So, on a 4x5, you just colapse the bellows down to a short length to achieve this. Now, ig you want to see a photo of a homemade 4x5 pinhole camera, go to http://www.janikphoto.com and click on the pinhole section. You'll see that you can build a pinhole camera with only a few dollars worth of supplies. It had no viewfinder and that actually made photo taking even more fun because you had to become one with the camera as you guessed where to aim it...
-- Jason Janik (email@example.com), August 06, 2001.