sinar dbm and a set of symmar-s lens cells

[mikec]

Always on the lookout to cheaply filll in holes in my lens range, I picked up a set of very good Symmar-S 180mm cells to go with a Sinar f5,6 copal1 DBM board that has been in my bits box for ages. No problems with mating them, but I see that the iris when fully opened does not completely uncover the central lens opening. After checking against a Symmar 5,6 150/256mm, also in DBM, it is clear that the board is set up for a 150mm focal length. So I can convert my light reading accordingly, or more permanantly, cover the original scale with a modified one. There might be another possibility however. Both DBM boards have the same 441.31.300 part number. I also find that my Sironar 5,6 100mm is also sitting in a board with that same part number, though obvously, the max aperture opening size is smaller. This leads me to speculate that Sinar were using the same hardware for all copal1 5,6 lenses, and just stopping the max iris opening accordingly. The aperture scales seem identical on the 100mm and 150mm boards. So it may be possble to save on the mental arithmetic by modifying the stop to suit my 180mm.

So before I get my screwdriver out,
Is my hypothesis correct?
Has anyone already done this? If so how?
If not, has anyone dismantled an older type of DBM board and seen how the aperture stop is implimented?

thx, Mike

[erie patsellis]

Mike,
my experience is limited to only a few, but you can adjust the aperture pretty easily, as I recall. A quick look with a good light will tell you for sure.


erie

[jeffoto]

I have the same setup, 180 Symmar S on DB board. I am looking for a copal shutter for the lens as I have no use for the DB board, so if you are interested in the board, shoot me a PM.

Thanks,

Jeff