Mounting Lens to Lens Board

[SodaAnt]

In the past, I’ve always bought LF lenses already mounted to lens boards. Now I have a bare lens that I need to mount to a board (Copal #0).

How much should the retaining ring on the back of the board be torqued? I ask because I’ve never met a fastener I haven’t been able to break by applying too much torque and I don’t want to break anything here.

 

[BrianShaw]

Tight enough that the shutter doesn’t move when in use. Too often it seems that they are torqued down too much.

 

[Alan9940]

Many LF shutters have a very small screw on the back that is raised slightly above the back of the shutter. If yours is intact, you can simply file a notch or drill a slight dimple that the screw head falls into, then you won't have to tighten down much at all; just enough to keep the shutter from jiggling around. If you don't have the screw, IMO it takes some effort to tighten enough that the shutter doesn't spin within the shutter hole.

 

[Axelwik]

I'll echo the above about not over-torquing it. I typically don't use tools, and simply turn the shutter until the lock ring is properly seated and it's not too loose, and that's all - only hand-tight. There should be a lip in the lock ring that rides inside the hole in the lens board - make sure it's properly centered and seated inside the hole.

 

[Ian C]

Bear in mind that both the threaded shank of the shutter and the flange are aluminum—not steel. The threads can be galled or otherwise damaged. So, the toque on the retaining ring should be limited to a safe value. I recommend applying a thin film of lubricant to the thread to prevent galling, screw the flange onto the lens to evenly distribute the lubricant, disassemble, then pass the lens shank through the lens board and fasten the retaining ring. I prefer a wax lubricant for this.


You can secure a shutter to prevent it from rotating relative to the lens board by cutting narrow strips of Scotch Double-Sided tape and apply them onto the front of the lens board in the area about the lens hole. This is a bit tricky to accomplish, but I have learned to do so.

Install the lens in the orientation wanted, install the retaining ring and tighten it firmly. The friction between the contact surface of the tensioned shutter housing, the tape, and the front of the board will anchor the shutter in place and prevent it from rotating relative to the board.

As you tighten the retaining ring, it’s important to use greater force into the ring than the torque applied to tighten the ring. This is to ensure that the tips of the wrench don’t slip out of the grooves of the ring and strip the grooves.