View Full Version : Dallmeyer 2B lens soft focus adjustment. Help required!

12-Aug-2017, 19:18
Hello, Would anyone be able to assist me? My Dallmeyer 2B soft focus adjustment will not rotate! What would be the best and safest way to free it? Thank you in advance for any replies!

Mark Sawyer
12-Aug-2017, 19:42
That issue plagues about 90% of the B-series Dallmeyers out there; they were factory-made to too tight a tolerance. Your best bet is a good soak in penetrating oil and lots of muscle...

12-Aug-2017, 22:17
Thank you Mark! Will try using penetrating oil... how long do you recommend I should soak it for before trying to loosen it?

Mark Sawyer
13-Aug-2017, 12:05
Overnight. Don't keep repeating it, or you run the risk of the oil penetrating to between the rear cells, fogging them, and having no access to clean it out.

Steven Tribe
13-Aug-2017, 15:00
In what position is the rear half cell stuck? And how much of the thread is visable?

If, for instance, the pointer screw is between I and IIII, it could mean that is has forced past the usual stop at I - or it is already almost a turn unscrewed. There was an example on ebay recently (Igor) in exactly this position.

I would be optimistic about getting this loose, even if it has been screwed in beyond the normal position. I have always found an impact device, combined with heating the outer and plenty of penetrating liquid to work - often quite suddenly. You would obviously remove the front cell first and protect the outer glass from wayward flames and falling tools. A hobby gas burner will always warm the outer brass thread before the inner brass (holding the lens) and the brass will always expand away from the glass. If you can apply torsional blows while the brass is still warm so much the better. Don't give up after the first attempt - suddenly, it will work.

I use a piston ring compresser with a protective tape inside to avoid scratches. I give blows to the protruding tightening mechanism. I imagine there are good oil filter removers which provide a good pressure all around the circumferance and already have a handle system. Two people with fours hands can apply far more torque than your left and right hands working in different directions!

Of course, if you have the "turn the barrel" model ( which have more problems usually) you should check for a locking screw which is sometimes installed in the barrel!

13-Aug-2017, 17:58
Or, if you don't want to use blow torches and hammer blows, make a giant lobster claw cracker type device out of two pieces of wood. Cut a semicircle the same diameter as the rear fixture, half
circle in the edge of each board. Make it about 10 inches from one end. line the circles with rubber inner tube pieces. Wire those ends of the boards together. Have one person hold the body of the lens. You grab the bitter end with your nutcracker and turn.

Tim Meisburger
13-Aug-2017, 17:59
Steven, so the tiny screw in the late model 2d I have should be removed, and just unscrew to introduce softness? Mine doesn't have any marks to indicate degree of softness. I always tried to twist it with the screw in, but worried if I used too much force I would shear off the screw. So, softness is introduced by move the entire rear element away from the front element? Seems too simple...

Steven Tribe
14-Aug-2017, 02:14
Need photo to judge, but if there is a screw in the barrel, well away from the iris and within the range of the hidden thread, then it is a locking screw. It can have no other purpose! The "turn the barrel version" had several versions, including one where there was a clockwise release - the direction of the engraved arrow will show the direct for release.

I don't know whether the locking screw was standard, or whether or it was a fairly standard addition to stop photo assistants messing up the softness adjustment and the studio finding out about the Unauthorised setting after many exposures! I think the lock screw was only for a single non-soft setting and attempting to lock it at different might lead to damage to the thread, but there might be "homemade - best studio practice" positions.

I am a little bit in disagreement with Mark about how many of the old versions have problems. The threads are well made with usual tolerances. But is not easy for the screw-in cell to stop exactly with the pointer at the null I position.
I have a couple of the split barrel French convertibles where the focussing track is also split into two halves. When these two are screwed together, they are tight exactly when the two half tracks match up! Super brass machining in the 1850's!

Tim Meisburger
14-Aug-2017, 03:17
Okay. I'll get that lens out this evening and take some pictures. I have not had an 8x10 since I moved to the US, and have not had that mounts since then, but hopefully I'll have a Kodak 2D to to mount that on.

14-Aug-2017, 08:26
I think what Mark meant is the Dallmeyer threads are fine, and so are more likely to jam if old oil turns to varnish in them. Course threads don't stick as often.

16-Aug-2017, 01:29
Thank you Steven, Mark and goamules for your excellent suggestions! Unfortunately I haven't had the time to tackle the problem as yet but hope to give it my full attention this weekend with the help of a friend. Steven, there is no thread visible. I know this might seem like a stupid question... in which direction should I try to turn the soft focus ring... to the usual left?

Steven Tribe
16-Aug-2017, 03:40
Understood - if you knew how many projects I have on a mental list of things to do....!

If we talking about the notched rear adjustment half cell, than it is the usual anticlockwise to unscrew. The markings will give you some idea of whether it has been screwed in beyond the normal "stop" position.

16-Aug-2017, 04:24
Anticlockwise... Thank you! Have you ever come across a cross-section drawing of the 2B or any similar Dallmeyer soft focus lens? All the best with your project list Steven!

Steven Tribe
16-Aug-2017, 05:35
There are plenty!
Here is an article by Dan.
The Dallmeyer x-section is shown towards the bottom on the left. Note that the "pointer" shown at the top left is somewhat exagerated in length!


16-Aug-2017, 23:54
Thank you Steven, What a wonderful resource 'Antique & Classic Cameras' is... I found the Dallmeyer section very interesting indeed! Thank you for the link! 'Pointer' duly noted!