4X5 Pinhole

[Edcculus]

I'm almost finished with my 4X5 Pinhole build!

I used these instructions
http://pinhole.stanford.edu/foamcore.html
http://pinhole.stanford.edu/dai.htm

Overall a fairly easy build. I picked up some old wooden film holders a few months ago for the project as well.

All I have left now is tape up the outside with black opaque tape to prevent light leaks and make the actual pinhole.

I'm also going take a piece of plywood plank that can attach to a tripod. I'll then rubber band the camera to the plank to keep it in place.

 

[Legion]

Make sure you get that pinhole perfectly round, or it won't have a proper lensing effect. When I use to make them I found a loupe and a lightbox very useful for checking.

 

[Edcculus]

Ive yet to make an actual pinhole before. From what I've read, the best way is the "dimple and sand" method. Make a dimple in some brasss shim stock with a sewing needle, then using very fine sandpaper, start sanding the dimple away.

I don't know exactly how I'm going to measure the hole. I have a 15x loupe with measurements built in, but I think I'll need something more like a 100X loupe to do the job. I'm also thinking about scanning and measuring, or using my enlarger. Scanning will take a lot longer, and Im not exactly sure how to calculate the enlargement of the hole if I were to use the enlarger.

 

[Legion]

You are over thinking it. Just make a little hole, you can work out the exposure later. Unless you have a laser drill you will never be able to reproduce the exact hole size anyway.

Dimple and sand is the way to go, but brass shim will be too thick. try first with a very sharp needle and kitchen foil. I have also seen guys use something as simple as a plastic chips packet.

You will also want to build some sort of cover for the front of the box to use as a shutter.

 

[Edcculus]

Thanks. I've come up with a way to measure the pinhole that should be pretty quick and easy. I'm shooting for a .30mm pinhole. If I can get close to that it will be fine. I'm just going to stick a clear ruler in my enlarger, measure the enlargement factor for 1mm, then use that when measuring the pinhole (which I will put in the negative carrier so the light projects through the hole onto the base board). If I sand a little then creep up on the size, it should be rather quick and easy.

I'm going to use the circle cutout with tape as a shutter. I'm using paper negatives, so the exposure time will probably be long enough anyways that all I have to do is put the dark slide back in place to stop exposure.

 

[fast14riot]

Try finding a few pieces of wire in the sizes close to your taget aperture. You will basically be making tiny guage rods.

You want the edges of the aperture to be as thin as possible so light doesn't reflect off them like looking through a pipe. The finer the edge, the sharper the image.

Cool stuff!


-Xander

 

[Russ T Blades]

For holes of .015 and up I use a set of the wire type spark plug feeler gauges to measure the size of the hole.