I am looking for information on the size of hole I need to make for the Ektar 203mm lens in an MPP lensboard (Mk7), the lens is as far as I undestand from the bloke in the shop (describing the items over the phone) is that the kodak ii in a prontor shutter and the Wray I asked about earlier is in a synchro-compour. Btw what are the relative merits of these shutters - what are the actual speeds I know the max speeds but not those in between. Thanks.

-- David Kirk (David_J_Kirk@hotmail.com), March 29, 2000

Answers

The mounting hole size is dependent on the shutter, not the lens that's fitted to the shutter. The thread sizes have been standardised for some time now, so that both Copal, Compur and new Prontor shutters with the same number are the same size. There might still be differences in the retaining ring diameter though, some are recessed, some aren't.

Your Ektar 203mm will probably be in a number 1 or 0 shutter, but check with the shop first. Also check that the retaining ring is included as well; a small item but difficult to come by on its own.

The number 0 thread size is 32.5mm and number 1 is 39mm. The recommended hole sizes are 34.6 and 41.6mm respectively, but this might vary with the design of the retaining ring.

Prontor shutters used to be made in East Germany I believe, but are now part of the Zeiss group. The older ones were a bit cruder than either Compur or Copal, but they're still reasonable shutters if they've been looked after.

-- Pete Andrews (p.l.andrews@bham.ac.uk), March 29, 2000.