Hi there, I have a used Omega C760 with a 50mm Rodenstock El-Omegar 1:3.5 and I find that if I am trying to make an enlargement greater than 8X10, to get the proper focus, I need to focus it to the point where the bellows is completely compressed and it won't stay in position. Any thoughts? As well, in general I find that I have to verify with a grain focuser everytime I do a print (even with it locked in position) and sometimes it's quite a bit of a difference. Any suggestions? Many thanks. Rick

-- Rick Mah (irkc@yahoo.com), September 16, 1999

Answers

Probably you need a recessed lensboard for a 50mm lens.

-- Thies Meincke (meincke@uni-hamburg.de), September 17, 1999.

What film size are you using? A 50mm lens probably only covers 35mm format. Yes, you should always check the focus with a grain magnifier.

-- Alan Gibson (Alan.Gibson@technologist.com), September 17, 1999.

Hi Rick,

A while back I came in contact with an Omega "something" that may have been the 760. It had alignments based on setscrews that didn't work very well. If this is what you have, check the alignment carefully and be very gentle thereafter. As for the bellows compression, a recessed lens board may be possible, or close up the bellows fully and let it sit a week or so. It may need to get used to being compressed. If there is a tension adjustment on the focusing, that may need to be tightened. All bellows push back a bit, and if the focusing is loose, it'll move. If you see focus shifts with everything locked (does the focus lock?), then either the head is loose somewhere, or you are getting negative "pop" due to excess heat. Has the thing got a heat absorbing glass? If it's an option, see if you can get one. You should always use a grain focuser, and it's common to see the negative move if you leave the light on too long. Time your routines so the negative either heats up fully, or doesn't heat up enough to move. Not always easy, but glass negative carriers are a pain too.

-- Conrad Hoffman (choffman@rpa.net), September 17, 1999.

I have a C760XL. I use my 50 with Omega's recessed lensboard; without it, I had the same problem as you.

-- The Dude (oblivious@cyberdude.com), September 18, 1999.

Later C760s have clamping screws to hold the lens head in place. Early units did not have this and can always be counted on to shift, at least mine does. I was told that Omega would fix it for free, then they quit making the 760, and I moved on to a V-35 and didn't follow up.

-- Bill Mitchell (bmitch@home.com), October 04, 1999.

You must use the recessed lens board with a 50mm lens. If your lens board is moving, there should be tensioning screws on both rack and pinions on the back. You can adjust the compression to any tightness you desire.

-- Gene Crumpler (nikonguy@worldnet.att.net), October 05, 1999.