Don H Marks

That is very nice, thank you for the link. I built mine to try time-laps to see if I like it before buying gear I might not use much.

A short video of the intervalometer in action:

The servo cycles back and forth and pushes the frame release forward via a spring-loaded lever.

I put together a simple intervalometer for one of my Bolex cameras. The design uses a Radio Control Vehicle servo and a simple 'servo tester' box that cycles the servo at various speeds.

I did contact Rafacamera about adapters for these lenses. Based on that outer measurement of the threads he indicated the m28x0.5 to m52x0.75 adapter already in stock might fit. Also, may be able to custom make other sizes.

Maybe I'm not looking in the right place, but I find it hard to believe there is no big list of D-mount lenses compiled to a table or single website. I have collected some pdf files listing D-mount lenses but only for Kern, Berthiot and Wollensak. Even then, I think I have only partial lists.

I do get 27.9mm when I measure the lens cap threads on the D-mount 36mm 1.8 Switar. Same size as the 13mmm 0.9.

Without actually dismantling the Yvar 13mm 1.9, I'm a little suspicious if it is really six element, because in another catalog "February 1952" the same diagram is used for the Pizar and or Switar 12.5mm:

Thank you for the correction on the Switar 36mm 1.8 as being 5-element. I also found a Bolex catalog in my collection of physical documents. Its content is a little different from the PDF files I have collected. In that physical catalog (November 1952) it is showing the 12mm Yvar 1.9 as six-element. If so, that is the only six-element Yvar I have come across in my stash of Bolex literature. Most Yvars being 3 element with a few exceptions.

After years of searching I finally found a second 27mm lens cap. As far as I know only the Switar 36/1.8 and 13/0.9 used that lenscap and I only had one to share between the two of them. I don't think any of the other D or C mount cameras used that size. The way I found it was just scanning many images looking for the distinctive relationship between the Kern/paillard text and the size of the cap. It is uniqe none of the other caps look that way. The little Switar 5.5/1.8, however, takes the easy-to-find lenscap common to the Yvar D-mount lenses.

That post makes me feel like one of the youngsters. Those cameras were all from before I was born. Though, only by one year.

Another good rule of thumb is that one can't make a focused image if the subject and film are less than 4 focal lengths apart.

This is not my picture, I found it on the internet. But it does show what I have in mind. You can see the adapter on this one is a vintage piece. Though I can't make the letters other than U.S.A

Mine just came today. I don't have a standard C-Mount lens to test yet, but I did measure it and it will likely work. I got these numbers off the internet, not sure how correct they are. D-mount flange focal = 12.29 C-mount flange focal = 17.526mm Difference = 5.236mm I measured the adapter and it was about 5.18mm +/- some hundreths. The lens I have in mind is the 75mm Yvar, as my Octameter has a setting for 75mm. Another I was looking at was the 3" Wollensak.

This is the table for Regular-8 to which I refer when focal length discussions come up. For simplicity the numbers are rounded and the field of view used is the diagonal of each format's film gate.