Mounting a pinhole

[Neph]

Hi all,

Please accept my apologies if this is a silly question and if I've posted it in the wrong place.

I was thinking about mounting a pinhole into a spare lens board I have. The lens board has (I think) a Copal No. 1 retaining ring on it. I'm a bit unsure about it as it came with the camera when I bought it used. I've measured it and its approximately 39mm.

Would it be possible to screw a 39mm to 52mm filter step-up ring into it (do the threads match)? This would enable me to mounting the pinhole to the inside of the step-up ring and use my 52mm filters on the front. Can anyone help?

Neph

[Jac@stafford.net]

Do whatever you wish to mount a pin-hole to a shutter or a naked lens board. The exposures will be so very long that it makes no difference whether you use a shutter or a hat to block the pinhole.

[Neph]

Hi Jac@stafford.net

Thanks for the reply, my question really is can I screw a step-up ring to a Copal 1 retaining ring.

[Jim Jones]

The threads of a 52mm filter are finer than the threads in a 39mm lens mount. Consider making a new lens board out of mat board, plywood, or whatever you have handy. Cut a hole in this and epoxy a 52mm filter ring from which the glass has been removed into the hole. Now you can stack filters and a pinhole mounted in another filter ring.

[Randy]

...or, if you insist on using the shutter, tape the pinhole to a piece of matte board cut circular to fit down inside the threaded part of the shutter, front or back. A little black tape would keep it in place.

[Neph]

Thanks for the excellent suggestions

[Celier]

1. Just think of simple line geometry. If there is some obstacle between the pinhole and your film where you want the image then there will be mechanical vignetting.

2. With say an ILEX #3 to obtain the maximum FOV the pinhole should be .7mm in front of the shutters. Again think of the simple line geometry. Most often people do not need the maximum FOV.

3. I personally like the ILEX #3. But I'm fairly unusual in that mine are electric and I have a driver.

You can buy ILEX #3 off eBay for between US $ 20 and US $ 90.

All the best: https://diceus.com/what-is-onsite-offshore-model/