Mounting enlarger and process lenses into Copal/Compur shutters.

[kfed1984]

Can anyone elaborate on the nuances of mounting enlarger and process lenses into standard shutter bodies like Copal and Compur?

I have a Schneider G-Claron 270mm WA, f6.3, which threaded into a Copal 3 body without issues.

In the enlarger lens body of my G-Claron, the distance from back to front lens elements is 88.73mm. When mounted in Copal 3 body, it measures 88.67mm, so the lens spacing between front and back elements is the same in both cases effectively.

Not sure if this is a coincidence or if lens bodies are designed with this in kind of thing in mind. The great thing about this lens is that it covers 11x14 at infinity without any issues when stopped down, as seen with a loupe through the ground glass.

I see that some LF lenses, like my Schneider Symmar S 300, have shims to control the front-back lens spacing. So this spacing is probably a critical and a controlled dimension.

My question is, does the shimming/lens-spacing in the enlarger mode still apply to the focus-to-infinity/camera mode? The light cone angles are quite different in both cases, so I'm suspecing the spacing in the enlarger mode is only applicable for enlarging purposes.

Same question applies to Apo-Ronar lenses, of which I have quite a few. But these are probably better off mounted in a Packard type shutter.

[Joseph Kashi]

Can anyone elaborate on the nuances of mounting enlarger and process lenses into standard shutter bodies like Copal and Compur?

I have a Schneider G-Claron 270mm WA, f6.3, which threaded into a Copal 3 body without issues.

In the enlarger lens body of my G-Claron, the distance from back to front lens elements is 88.73mm. When mounted in Copal 3 body, it measures 88.67mm, so the lens spacing between front and back elements is the same in both cases effectively.

Not sure if this is a coincidence or if lens bodies are designed with this in kind of thing in mind. The great thing about this lens is that it covers 11x14 at infinity without any issues when stopped down, as seen with a loupe through the ground glass.

I see that some LF lenses, like my Schneider Symmar S 300, have shims to control the front-back lens spacing. So this spacing is probably a critical and a controlled dimension.

My question is, does the shimming/lens-spacing in the enlarger mode still apply to the focus-to-infinity/camera mode? The light cone angles are quite different in both cases, so I'm suspecing the spacing in the enlarger mode is only applicable for enlarging purposes.

Same question applies to Apo-Ronar lenses, of which I have quite a few. But these are probably better off mounted in a Packard type shutter.

Some barrel-mount G-Clarons, earlier Schneider Repro-Clarons, and Computar process lenses were apparently designed to screw directly into various Compur/Copal standard shutters without the need for custom machine work. I know that my initially barrel-mounted 240 GC screwed into a standard Compur 1 without any fuss and works well, so that spacing would seem to be correct. Note that a new aperture scale would likely be needed, depending upon which lens was previously mounted in the shutter.

SK Grimes has a table on their web site that shows some lenses that can be mounted into various shutters, some without the need for additional machine work, but most seemingly require custom machine work. Here's the link: https://skgrimes.com/lens-mounting-to-shutter/ This list may not be complete, so a call to Adam Dau at S K Grimes in Rhode Island would be in order.

[ic-racer]

Spacing of the elements can alter flatness of field. For distant images, you might need to experiment with the best spacing to get center and edges sharp for your purposes.

[kfed1984]

going from enlarger to camera mode, would you say I need to space out farther or closer?

thanks for the feedback BTW.

[Dan Fromm]

going from enlarger to camera mode, would you say I need to space out farther or closer?

thanks for the feedback BTW.

No change needed.

Re post #2 above, G-Clarons, Repro-Clarons, Comparons and Componons (older jes' plain and newer S-) have cells that are direct fits in various sizes of Compur/Prontor/Copal standard shutters. Some, not all, Boyer lenses' cells go directly into shutters. Schneider process and enlarging lenses sold in barrel are in barrels whose dimensions and cell spacings match the shutter.

Most other process and enlarging lenses' cells are not designed to go directly into shutters. I have a small pile of these, have adapters whose fronts accept the lenses and whose rears screw into a shutter. For mine, usually Copal #1. This can cause vignetting on 4x5 and larger formats. No problem for me 'cos I shoot 2x3.

[Drew Wiley]

I'd just refer to a specialty service like SK Grimes. They also have a compatibility chart online, stating the correct shutter for various process lenses they have already fitted, and what if any modifications are needed. For G-Clarons, it's best to buy them in shutter to begin with, since you might spend just as much for the shutter alone these days.

Some process lenses, like the 4-element Apo Nikkors, are superb at infinity as well as close up with no need for spacing adjustment.