Preventing lens rotation when cocking shutter

[tonyowen]

How can a lens be prevented from rotation on its lens board when cocking the shutter?

A #0 shutter I have has a protruding screw that fits into a notch in its lens board, so preventing rotation.

I've a Symmar 180 whose cells are NOT fitted to a #1 shutter, but fitted to a Schneider (???) barrel with integral iris.
On the face of the Schneider barrel's mounting shoulder is a grub screw, but it is flush [not protruding] and I'm hesitant about trying to unscrew it a bit in case something inside the barrel comes adrift!!!!!

I do not want to over-torque the retaining nut holding the Schneider barrel in place.

I've tried pieces of masking tape [between shoulder and face of the lens board], but they do not offer sufficient friction to prevent rotation.

So any ideas and information welcome.

regards

Tony

[Pfsor]

Instead of a piece of the masking tape put there a DIY washer made of thin rubber. You will need to look for a suitable rubber piece. In the worst case you could cobble it together from rubber used for kitchen jars.

[Pere Casals]

How can a lens be prevented from rotation on its lens board when cocking the shutter?


Retaining ring should be able to secure the barrel to the board without overtorking, lubricate well the thread (I use Interflon Food Lube for that, it is atoxic, permanent and high performance).

Check that the ring can press the board (board thickness, do you need a shim ?).

A fast trick I used once is a hot glue gun, not nice but this is in the back on the board :).

Regards.

[Pfsor]

A fast trick I used once is a hot glue gun, not nice but this is in the back on the board :).

Regards.

And when you want to change the lens - you call plumbers?

[Pere Casals]

And when you want to change the lens - you call plumbers?

Hot glue is removed very easy from metal... specially if it is cheap glue

[faberryman]

If you don't want to tighten down your retaining ring, you could hold the shutter/lens barrel when cocking the shutter.

[Leigh]

I've a Symmar 180 whose cells are NOT fitted to a #1 shutter, but fitted to a Schneider (???) barrel with integral iris.
If the barrel does not have a shutter, where is the shutter you're cocking that rotates the lens?

- Leigh

[tonyowen]

If the barrel does not have a shutter, where is the shutter you're cocking that rotates the lens? - Leigh
Sorry the question was generic [ie prevention of rotation], my problem is specific [to prevent rotation as I move the aperture ring] - it is very tight and the material is very very smooth metal.
regards
Tony

[Dan Fromm]

Tony, if the aperture control is tight the barrel should be taken apart and cleaned. Don't lubricate the diaphragm's blades with graphite, as many claim to do. The blades aren't the problem.

[tonyowen]

Tony, if the aperture control is tight the barrel should be taken apart and cleaned. Don't lubricate the diaphragm's blades with graphite, as many claim to do. The blades aren't the problem.
Dan,
Thank you for your concern
regards
Tony

[Jac@stafford.net]

On the face of the Schneider barrel's mounting shoulder is a grub screw, but it is flush [not protruding] and I'm hesitant about trying to unscrew it a bit in case something inside the barrel comes adrift!!!!!


It would help if you could post a picture of the screw.

[Leigh]

Sorry the question was generic [ie prevention of rotation], my problem is specific [to prevent rotation as I move the aperture ring] - it is very tight and the material is very very smooth metal.
regards
Tony
Hi Tony,

Might I suggest you edit the thread title to more accurately reflect the subject.

- Leigh

[tonyowen]

Attached are three images - responses follow quotes
172211 172212 172213


Tony, if the aperture control is tight the barrel should be taken apart and cleaned. Don't lubricate the diaphragm's blades with graphite, as many claim to do. The blades aren't the problem.
Dan, the click-stop aperture ring moves smoothly without any indication of stiffness or rotational problem. The situation is the knurled ring is not deep and wide enough to get a good ‘finger grip’ and also that the torque required, though light, is not resisted by the frictional force generated by the clamping force on the lens board.


It would help if you could post a picture of the screw.
Jac, the first two images show the protruding grub screw on a #0 shutter and the flush screw on the shoulder face of the iris body. I could examine both screws to determine any similarity i.e. see if the screw in #0 shutter screws flush and/or determine the amount of realistic protrusion of the screw on the iris barrel, by unscrewing it.

QUOTE=Leigh;1417263]Hi Tony, Might I suggest you edit the thread title to more accurately reflect the subject. - Leigh[/QUOTE]
Leigh, facetiously how about “Please advise a means of resisting toque generated by the adjustment of an optical device fitted to the lens board of a large format camera” Seriously, my first posting associated the autorotation device on my #0 shutter to the specific situation of the Schneider barrel with integral iris.

Regards
Tony

[Dan Fromm]

Tony, which camera -- lens board, really -- is the lens mounted on? And what is the ID of the hole in the board?

I ask because if the board is thin -- think Pacemaker Graphic -- and the hole is the correct diameter the retaining ring's centering ridge will contact the back of the barrel before it contacts the board. I've had this problem, also have boards with the hole too large, same result. My solution is to turn the retaining ring around so that the centering ridge faces the rear and the smooth -- normally rear-facing -- side of the retaining ring contacts the board. If you haven't done this, try it.

[tonyowen]

Tony, which camera -- lens board, really -- is the lens mounted on? And what is the ID of the hole in the board?.
Hi Dan,
Calumet CC400, lens board made from two pieces of thin ply cross orientated and glued together that approximates the thickness of the relevant part of a Calumet metal board. Id of hole is roughly cut to match M39 male mounting thread - have not tried reversing ring, but if I do then the 'spanner notches' will be hidden.
The retaining ring's centering ridge is very shallow and seems shorter that the thickness of the wooden lens board - but I'll check this .
regards
Tony