Archived posting to the Leica Users Group, 2001/04/07
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Actually, the focal length would be from the plane of the pin-hole to the film plane- I made a pinhole in a piece of shim brass, and then trimed it to fit and old 39mm filter ring. The thread is not the same as the camera, but it holds on enough for the use of the pin hole. The distance in this case is about 42mm, so it is pretty much like a normal lens as far as perspective is concerned. Incidentally, the best pin holes I have made were by taking a piece of .030" shim brass- I got it at the local Ace Hardare!, and taking a sewing machine needle- the 'ball point' kind that is used for sewing polyester. The point is not so much 'sharp' as rounded as these needles were designed to open up the fabric and go between the fibres instead of going through them- something about maitaining the elasticity of the fabric's seams. The needles of this type are superb for making pin holes You take a piece of the shim brass, and lay it on a scrap of hard wood- I have a little piece of oak that I use for various things around the house, and it works fine. Lay the brass on the wood, and make a 'dimple' in the metal- like a tiny repoussee dot, and don't go all the way through! Now take the piece of brass, turn it over so the dimple is now a small bump, point ing up. You can then take a piece of 1500 grit wet/dry sandpaper, and with a light circular motion, start sanding the bump off the metal surface. You will get a pinhole and it will have a knife edge, very thin and the refraction will be a lot better than just poking a hole in it, or drilling which makes the hole like a 'tube' through the metal, and the image is not very well defined as a result. When you finish, examine the hole- it should be as round as possible, and you may have to take three or four stabs at it before you get one with smooth round edges without burrs! It is pretty much an experiment in refraction, and the images are really soft with a 35mm camera, but it is a fun way to fritter away an afternoon! Happy long exposure snaps!! Dan - ----- Original Message ----- From: "Jeff Moore" <jbm@oven.com> To: <leica-users@mejac.palo-alto.ca.us> Sent: Friday, April 06, 2001 5:15 PM Subject: [Leica] Re: what's the point of a leica pinhole??? > 2001-04-06-16:27:55 Kyle Cassidy: > > why make a pinhole out of a leica body cap? > > Fer one thing, you can get closer to the filmplane, and thus get a > shorter "focal length" -- kinda like 30mm, I seem to recall. So if > you want a wideangle pinhole camera, the Leica's a better bet than an > SLR, which would be more likely to have a 50mm-ish perspective. >