Making a DOF scale for focus helicoid

[Fragomeni]

I’m working on a handheld 612 camera. The lens I’ve chosen is a Schneider 65mm f8 Super-Angulon which is mounted in the original Schneider focus helicoid. The helicoid is great except it was not made with a dof scale for some reason so I would like to find a way to add one if possible. Can anyone offer any wisdom on how to best determine the placement of distance marks to make an accurate dof scale for this lens?

 

[Donald Qualls]

Many older cameras had a DOF table mounted on a handy flat surface (like the film door) -- I have a Balda Jubilette (scale-focus 35mm folder) that has this method, a rectangular plate mounted on the back of the camera. One axis is aperture, the other is set distance. You could print something like this, laminate it (for durability) and glue it to the back of the camera.

 

[Fragomeni]

Many older cameras had a DOF table mounted on a handy flat surface (like the film door) -- I have a Balda Jubilette (scale-focus 35mm folder) that has this method, a rectangular plate mounted on the back of the camera. One axis is aperture, the other is set distance. You could print something like this, laminate it (for durability) and glue it to the back of the camera.

This is a great back up plan if I can’t make a scale. I hadn’t thought to just make a table for the back of the camera but that would indeed be an easy solution. Thanks for this idea!

 

[David A. Goldfarb]

Large format lenses don’t have DOF scales, because the DOF calculation depends in part on the format used.

Monorail cameras can use DOF scales on the rear focus knob that are independent of the focal length of the lens, though they make assumptions about the format in use. Sinar has a good DOF calculator on the rear knob of the Sinar P and some F models as well, if I remember correctly, and there are instructions for making a DOF ring for a monorail camera on the LF Forum at https://www.largeformatphotography.info/dofknob/

If you’re making a camera with a helicoid and a distance scale, you could compute the DOF table (there are some web pages that can automate that to make it easier), and then add DOF markings to the scale like most modern 35mm and medium format cameras have, but depending on the pitch of the helicoid, you might find it hard to print it legibly. In that case, just print the table and tape it to the back of the camera as Donald Qualls suggests. For 6x12, you can probably just use the medium format or 4x5” tables that were printed on the focusing hood of various press/technical cameras.