View Full Version : Mentor focal plane shutter cameras: shutter reliability?

Oren Grad
31-Aug-2011, 07:55
The GDR-made Mentor cameras with focal plane shutter come up for sale from time to time here and on eBay.

How reliable is the shutter in these cameras? How difficult is it to repair? Does anyone know of a shop in the US that would be comfortable dealing with it?

31-Aug-2011, 13:09
Ed Romney, in his many books on camera repair, claimed that the only large format focal plane shutter cameras that were repairable were the Graflexes. In support of this position I can only say that if Romney had been able to fix a Mentor he would have written a book (or pamphlet) on how to do it and sold the directions. I think the basic issue is whether the Mentor has one or two shutter curtains. If it has two (moving in opposite directions) it probably isn't repairable. The 2 curtain Graflexes (for example the compact Graflexes) seldom work. The single curtain Graflexes can usually be made to work (20 of my 25 Graflexes work, and I have hopes of getting the others to go).

31-Aug-2011, 14:44
It is dual curtain, but rather unusual in being hard coupled - the time setting mechanically regulates the width of the slit by shortening the coupler tape. The main weakness is wear to the tape, which has to go around a sharp edge. Nonetheless, Mentor shutters are pretty nice - almost immune to capping, less prone to fading and nowhere near as hard to adjust as large shutters with independently timed curtains.

Personally I think the praise of the Graflex shutter is exaggerated - it is a mechanism utterly dependent on irregular and non-constant spring tension, with a enormous length of crinkling rubber cloth to build up friction as it ages. While it does not take much to get a stuck Graflex shutter to (sort of) run, it is really hard to get them back to factory accuracy (short of replacing the entire wad of shutter cloth - which is prohibitively expensive).

31-Aug-2011, 15:13
As a repairman who has seen my fair share of rubberized cloth FP shutters, there is a very reliable shutter on Graflexs. These are on the Crown Graphics. That cloth seems to last forever. Graflex even reshuttered older cameras with the material and that is one reason why my Graflex SLRs are so reliable. I always look for a reshuttered camera. Now as for the tension spring. It is wound on a tapered arbor. It pulls evenly through out its range and is easy to re tension if needed. See those little oil holes? Oil them once in a while. Those rollers need lube and cleaning once in a while. The Mentors that I've worked on have very nice escapements but the material gets dry and stiff. . I did have some luck softening one by soaking in Naptha and then spraying it in Lemon Pledge. Strang sounding I Know but it did work.

Dan Fromm
31-Aug-2011, 16:32
Ken, Crown Graphics don't have focal plane shutters. Are you thinking of Pacemaker Speed Graphics?