Mounting a lens in a lens board

[tom_westbrook]

This must be a hopelessly 'newbie' question, since I haven't found the answer anywhere on the net or in 3 LF books (Kodak, Simmons, Stroebel). FYI, I don't have any lenses or lens boards, yet (hopefully I will next week).

 

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Is mounting a lens in a lens board a critical or precision operation? How is it done? I'd guess the front/rear lens elements have to be separated to fit it in the hole in the lens board, so how does one know that the elements are spaced properly when putting them back together? Do different lens boards require different mounting techniques (I�ll be using Arca-Swiss 110mm boards)? Is it pretty much the same as mounting a lens on an enlarger board? What�s the accepted orientation of the shutter controls after mounting, or does it matter?

 

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Thanks!

[conrad_hoffman]

It isn't terribly critical, and I've done some pretty servicable

mounting jobs with layers of matte board and an X-acto knife.

The "right" way to do it is to mount the lens board in the 4-jaw

chuck of a metal lathe, center it, then bore the hole with a boring

bar. If the shutter has an anti-rotation pin, a hole or notch for

that is drilled, either by hand, or on the milling machine, depending

on what one has available. The rear lens group unscrews from the

shutter to allow mounting, and it will repeat its position when

screwed back in- moderate pressure, not too tight, not too loose.

People have mounted lenses with circle cutters, hole saws, and even

Greenlee punches, but for a perfect job you can't beat machine tools.

[john_hennessy1]

Assuming you already have a board of the right size: unscrew the REAR

element and the retaining ring, put the lens through the hole from the

front, screw down the retaining ring, replace the rear element. Orient

it however you like. Some shutters like a number 3 may interfer with

camera parts here and there forcing an orientation to accomodate that

problem. Screwing the retaining ring on or off is easier with a tool

intended for the purpose (like SK Grimes') but if you have nothing

else, use two screw driver blades on opposite sides of the ring. If

you use only one blade, the ring will bind and never really tighten.

 

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Here are the shutter hole sizes:

 

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Shutter number hole size

0 34.8 mm or 1.362"

1 41.8 mm or 1.636"

3 65.3 mm or 2.560"

3s 2.525"

 

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See the table at: http://www.skgrimes.com/products/index.htm

[s.k. grimes inc]

Yes, same thing a mounting a lens to an enlarger lensboard.

 

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Just like enlarger lenses some need to have the back element

unscrewed to assemble to the lensboard and others don't. Most lenses

used for photography have a shutter instead of the familiar enlarger

type iris barrel. But the principle is the same in both cases.