Archived posting to the Leica Users Group, 2001/04/07
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Oh my gawd... all of this and you still have a pinhole photograph! That looks like a pinhole photograph. Jim At 01:37 PM 4/7/01 -0400, Dan Post wrote: >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