Mounting lenses ... confusion!

[Uri A]

Hi folks,

I've got a couple of modern lenses for 8x10 (Schneider, Rodenstock, etc) in modern Copal #3 shutters and I am mounting onto Sinar boards. All available knowledge says that a #3 shutter requires a 64.something mm hole (there are TINY discrepancies about the EXACT size..), and sure enough my two Sinar boards are drilled to 65mm.

There are 3 elements involved: I've noticed that different folks use different words to describe them. I am not pretending to be Dr. Johnson here, but for the purposes of this discussion, lets call them:

1. The BOARD (self explanatory)
2. The SPACER (the non-threaded ring that fits between the BOARD and the RETAINER
3. The RETAINER: the threaded, flanged ring that you use your lens wrench (or screwdriver) on, to screw the lens to the shutter.

OK, so we're all on the same page. Now, I have three questions:

(a): What is the purpose of the spacer, insofar as the retainer could just as eaisily clamp down on the board? It seems that people argue about tenths of millimeters when it comes to drilling the hole in the board... Is it just to increase the amount of pressure (surface area) that is applied to the board (via the spacer) when the retainer is screwed down? If so, why isn't the retainer just thicker?

(b): If the retainer is responsible for applying pressure to the board, why do I have a spacer that is so narrow that it doesn't even touch the board when the retainer is screwed down (it is obviously for a #3 shutter due to the diameter)?

(c): If the spacer is indeed designed to provide mounting pressure, why are we so pedantic about the exact hole bore being 64.whatever 1/10 mm, insofar as the outside diameter of both my spacers is 70mm and the outside diameter of the threaded lens barrel is somewhere around 62-63mm?!

Thanks for your time!

[Arne Croell]

Hi folks,

I've got a couple of modern lenses for 8x10 (Schneider, Rodenstock, etc) in modern Copal #3 shutters and I am mounting onto Sinar boards. All available knowledge says that a #3 shutter requires a 64.something mm hole (there are TINY discrepancies about the EXACT size..), and sure enough my two Sinar boards are drilled to 65mm.

There are 3 elements involved: I've noticed that different folks use different words to describe them. I am not pretending to be Dr. Johnson here, but for the purposes of this discussion, lets call them:

1. The BOARD (self explanatory)
2. The SPACER (the non-threaded ring that fits between the BOARD and the RETAINER
3. The RETAINER: the threaded, flanged ring that you use your lens wrench (or screwdriver) on, to screw the lens to the shutter.

OK, so we're all on the same page. Now, I have three questions:

(a): What is the purpose of the spacer, insofar as the retainer could just as eaisily clamp down on the board? It seems that people argue about tenths of millimeters when it comes to drilling the hole in the board... Is it just to increase the amount of pressure (surface area) that is applied to the board (via the spacer) when the retainer is screwed down? If so, why isn't the retainer just thicker?

(b): If the retainer is responsible for applying pressure to the board, why do I have a spacer that is so narrow that it doesn't even touch the board when the retainer is screwed down (it is obviously for a #3 shutter due to the diameter)?

(c): If the spacer is indeed designed to provide mounting pressure, why are we so pedantic about the exact hole bore being 64.whatever 1/10 mm, insofar as the outside diameter of both my spacers is 70mm and the outside diameter of the threaded lens barrel is somewhere around 62-63mm?!

Thanks for your time!

The "spacer" does not go on the back of the board, it is there to be mounted between the shutter and the front of the board, so that the shutter is set a bit off of the board. This order is not so important for your Sinar boards, but is needed for the much smaller Linhof boards (or similar sizes) where the board locking tab would otherwise interfere with the shutter itself. Mounting the retaining ring from the back through the spacer with the board in place is a bit fiddly, but there is no other way to do it.

[Tracy Storer]

Do not forget, some people use wooden cameras with thicker lensboards. In their case the spacer is omitted from the assembly.

[rdenney]

The retaining ring has a shoulder that extends into the hole on the board. Different retaining rings have different shoulder dimensions, and some rings are flat with no shoulder. This is why the holes in used boards differ slightly in size (and also why the recommended hole size differs slightly).

In my opinion, you do not need the spacer, nor do you need to worry about tenths of a millimeter, for mounting your lens to a Sinar board. You only need the spacer if the retaining ring doesn't get sufficiently tight onto the board because it bottoms out on the threads.

If the retainer is a bit loose in the hole, it's no problem. Center it as best you can, tighten it down, and then don't worry about it. Being parallel is important. Being perfectly centered is not--often you'll be applying rise, fall, and shift in far greater amounts anyway. Within a millimeter is plenty close enough.

Rick "who has drilled holes with a hole saw and then enlarged them with a drum sander, for smaller formats than 8x10" Denney

[Mark Stahlke]

The spacer goes between the shutter and the board. Without a spacer the aperture ring will bind against the board. Some Copal 3 shutters also have a pin on the back that will prevent the shutter seating against the board without a spacer.

Spacers come in two different thicknesses. The thick spacers are used with thin metal boards. The thin spacers are used with thick wooden boards.

[BrianShaw]

In my opinion, you do not need the spacer, nor do you need to worry about tenths of a millimeter, for mounting your lens to a Sinar board. You only need the spacer if the retaining ring doesn't get sufficiently tight onto the board because it bottoms out on the threads.

Thanks for answering the ignorant question I didn't have a chance yet to ask: what's a spacer? None of my lenses have an unthreaded spacer nor do they seem to need one nor do any of my aperture rings bind. I can imagine a situation where a space could be needed but have not yet (about 30 years of LF experience) experienced the need personally. Maybe I don't have enough lenses or cameras!

[Mark Stahlke]

A picture is worth a thousand words. Here is my Nikkor M 450mm in a modern Copal 3 shutter mounted on a thin metal board with a thick spacer between the shutter and the board. You can see the pin and the silver aperture ring on the back of the shutter. Without the spacer the shutter will not sit flat against the board due to the pin. If I removed the pin the silver aperture ring would bind against the board.

[BrianShaw]

Yup, that's worth a 1000 words. I've never seen such a thing. Thanks. How very useful. WOW, where do they come from?

[BradS]

The Copal #3 shutter mounting is different from that of Copal #0 and #1 because the #3 is so big. The spacer allows the #3 to be mounted (as shown in the photos above) on a Linhof Technika style board in a manner such that the shutter controls do not interfere, or, are not impeded by the camera itself. The "spacer" allows the massive copal #3 shutter to stand off from the board thus allowing the shutter controls to move freely - without interference from the lens board sliding locks for example.

The sinar boards, are much larger than technika style boards. There is plenty of room on the Sinar board for a Copal #3 shutter. The copal #3 can be mounted flat on the Sinar board. To do this, the hole in the sinar board is usually a little bigger - closer to 65mm. In this case...

1) remove the rear lens group
2) remove the retaining nut and the spacer.
3) insert copal #3 shutter into the hole.
4) put spcer on from the BACK of the board. It should fit through the hole.
5) screw the retaining ring - it fits inside the spacer and screw down
6) insert the rear group

Notice that if the hole is not big enough for the spacer to fit through - you cannot do it this way. However, every Sinar board that I have ever seen that was factory drilled for a copal #3 works this way. Virtually every technika board with a copal #3 hole works the other way...

make sense?

[BradS]

4) put spacer on from the BACK of the board. It should fit through the hole.

This is incorrect. The spacer should NOT fit through the hole. Sorry for the confusion. I was working form memory and low on coffee.

so, the corrected step is:
4) put spacer on from the BACK of the board. It should not fit through the hole.