Pinhole Pentax

[Klainmeister]

scan it at the highest possible resolution you can (mine is like 2000 dpi) enlarge that image in a graphics program - Gimp is free - and then select it with a circle tool to tell you how many pixels wide it is. Multiply: number of pixels * inches-per-pixel and voila - pinhole diameter!

I remeasured mine with a microscope once and the method was pretty damned accurate.

What he said!

[pbromaghin]

Hey, thank you guys. This is going to be a cool little project. Cheap, and even easy with your help. This camera was the first luxury purchase my wife and I made in 1982 after I got my first real job out of college. It pains me to see it doing nothing on the shelf and using it this way makes a virtue of the dead light meter.

[pbromaghin]

One more thing.

To get the focal length, do I just measure from the film pressure plate to the outside-front edge of the body where the cap will be?

[Klainmeister]

Yes.

[RalphLambrecht]

My dear old Pentax ME Super has lost it's light meter and has been sitting on the shelf looking forlorn and lost for a couple of years. But today I came across this:

http://www.pinholeresource.com/shop/...category_id=14

Toward the bottom there's one for Pentax K mount. I've never done pinhole photography, but it looks fun. Does anybody know how these caps work? It sure would be nice to use to start using the Super again.

i made one ,yself for my nikons.yes, they work

[Jim Jones]

This is getting good.

nhemann - I have one of these: http://www.amazon.com/Japanese-Profe.../dp/B000UZET0M It would probably work.

I brought a similar, but much smaller (and cheaper) stone back from Japan years ago. It's the best of many methods I've tried for making pinholes.

[RalphLambrecht]

scan it at the highest possible resolution you can (mine is like 2000 dpi) enlarge that image in a graphics program - Gimp is free - and then select it with a circle tool to tell you how many pixels wide it is. Multiply: number of pixels * inches-per-pixel and voila - pinhole diameter!

I remeasured mine with a microscope once and the method was pretty damned accurate.

this is my take on it;

[RalphLambrecht]

would a slide projector or an enlarger work?

[Peltigera]

I have been practising this with my Canon EOS. I tried using my extension tubes with the body cap on the end and it works like a telephoto pinhole.

[Lowenburg]

I've made a pinhole from a Nikon 35mm body by taking the backing paper from 120 film, taping it over the lens opening in the body and punching a hole in it with a pin. I used 400 speed film and made exposures of 2-5 seconds in sunlight and it worked. Body caps work fine too if you happen to have one, but if not, improvise -- it's more fun experimenting anyway. Have a good time!