How much should I tighten the retaining ring?

[Policar]

Between the shutter and lensboard. Dumb question of the day.

If I tighten it until the lens doesn't rotate when turned I have to force it pretty hard. General wisdom says not to tighten metal against metal this tight, especially when dealing with anything remotely fragile. Am I going to break something or should I just tighten real tight? Yes I know this is a dumb question, but I'd rather be embarrassed online than in person so I'm asking here.

[Doremus Scudder]

Policar,

No dumb questions, only...

First, if you feel you need to tighten the ring overly much to keep the lens from turning, I would carefully check the board and the shutter to make sure the seat is good. Look for bumps, high spots, etc.

If you are new to this, check carefully for a little screw protruding from the back of the shutter where it seats against the front of the lensboard. Many shutters have these. They are intended to go into a hole in the lensboard to keep the shutter from rotating. If your board has an appropriate hole, line these up. If not, remove the screw and save it. It's not really necessary. If you tighten things up with the screw in place but not in a hole in the board, you can damage the shutter.

Once you are sure the shutter/lensboard seat is good, check how the ring seats in the hole. Many rings have a ridge that is meant to fit between the threaded lens barrel and the hole. This takes up extra slack, however, if the ridge is wider than the lensboard is thick, you will simply end up tightening the ring against the back of the shutter and not against the lensboard. This allows the lens/shutter to rotate. If this is the case, you can make spacers from paper, cardboard, plastic or other suitable material to take up the extra room. These need to go between the seating portion of the retaining ring and the back of the lensboard.

If everything is in order concerning the above two points, you should be able to tighten the ring until the shutter does not turn. However, if you have slippery components (all smooth surfaces, etc.) then perhaps a bit of a shim from rougher material between shutter and lensboard will do the trick. Just make sure that whatever you do doesn't prevent the rear element from screwing in all the way. This would affect lens element spacing and degrade the image.

Hope this helps,

Doremus Scudder

[Frank Petronio]

You're lens has to be mounted secure enough that it won't turn when you cock the shutter. One of the official flat steel $19 eBay Rodenstock/Toyo lens wrenches makes it easier to apply firm, even pressure so you don't break the ring by accident. While screwing like metals together is a no-no, in most cases it isn't too hard to get the ring to release later.

What I do is tighten with the wrench "firmly enough that the lens won't rotate on its own" and then throw the lightweight flat lens wrench into my pack so I can retighten the ring in the field if it should ever come loose.

[Bob Salomon]

We are the Rodenstock, Linhof and Wista distributor for the USA. When we need to mount a lens to a board we tighten it as tight as we can using hand pressure so the shutter will not accidently loosen on the board. To do so we know that the Linhof and Wista boards are properly milled (not drilled) so there are no stresses or strains on the boards like those that can occur from drilling or hole cutting a board.
We do not expect our users to have to retighten a shutter once it leaves us or our service center.

[BrianShaw]

... Many shutters have these. They are intended to go into a hole in the lensboard to keep the shutter from rotating. If your board has an appropriate hole, line these up. If not, remove the screw and save it. It's not really necessary. If you tighten things up with the screw in place but not in a hole in the board, you can damage the shutter. ...

Feel free to skip this step. These screws, when saved, just get lost.

[Policar]

Thanks, everyone. I bought my lenses used, so the screws were already missing, unsurprisingly. But my lensboards don't use them, anyway.

I'm just going to leave things as is and not worry about anything being over-tight; I only tightened to the point the lenses didn't rotate when turned. Glad to learn, in this case, it's not the end of the world to tighten metal on metal.

I may just be freaking out since my friend got an EOS adapter stuck on his F-mount lenses and I'm overprotective of my own gear.

[E. von Hoegh]

Metal on metal is no problem. After all, it's what holds your car engine together.
Aluminum on aluminum is sometimes problematic, though. If you're worried, rub a little beeswax on the threads and tighten away.