Graflex RB Focus Brake

[Grahamakz]

Hi I am just starting to use a Graflex RB D and need to lock the focus for multiple shots and changes of aperture etc. I cant see anything on the camera and dont want to do an excessive modification. At the moment I am experiment with a small wooden wedge between the focussing knob and body. Anyone done something like this and has a better idea.

[domaz]

Also not elegant but maybe a small C-Clamp?

[Jim C.]

The springyness of the compressed bellows to extended cause the drift in focus,
there isn't a lock for the focusing rack and pinion.
You can try extending the bellows out all the way to relax the bellows then focus
otherwise a spring clamp on the geared focusing rail.

[Grahamakz]

Thanks Domaz and Jim. A spring or C clamp is certainly more elegant than my wedge. I will try them both later today. Jim I agree the bellows causes some of the rebound. The rack on my RB D is a bit too free for my liking and can be knocked out at the slightest touch especially if shooting from low angle and with full extension. I don't want to make any modification or screw marks on exterior of body. In the long term. I suppose I am looking for something that puts friction on the rack from inside but offers an unobtrusive fixed lever. Any ideas?

[Jim C.]

If you look thru the holes in the rack, the pinion gear shaft runs the width of the camera,
it looks like there is room in there for mechanical locking mechanism that would grip the shaft to lock it.
It'll take a bit of engineering to make something that doesn't require holes to be drilled thru the
camera body and to be unobtrusive.

Another thought is in that same area add a flat spring and a shaft support block to apply friction to the shaft,
the flat spring would need to 'tuned' so that it's not so strong that the it would take a lot of effort to extend the bellows and focus.

[Grahamakz]

Hi Jim, thanks for that. Both your idea of a spring clamp and Domaz's of c clamp work well enough to reduce the problem as a temporary arrangement. Especially if I clad the clamps or that area of the body to reduce friction damage to exterior and I am testing both. So thanks to both and for the moment I am able to continue using the camera with the problem pushed away in short term. I think you're right about being enough room there for something longer term and your ideas seem really good. If I can come up with something I can do myself I will describe it later. Thanks again most helpful.