RolandRB wrote:

You need to tape a broken piece of ground glass to the back rails of
the taking lens and using a lupe, adjust the focus to infinity while
looking at a distant scene. If your broken piece of ground glass is
from an old camera and it has a split prism then so much the better.
Then make the ground glass in the camera at the top be in focus with
this scene by using spacers or adjusting screws to adjust the ground
glass distance from the viewing lens. If you have one of these old TLR
Mamiyas then there is no point in using it unless you know the
adjustment for this is correct. It is often wrong for any camera you
might buy on ebay.

I've done it once. I found a maintenance manual for the 220 on line. The
220 uses shims but the 330 is much easier as it has three little adjustment
screws. I used a couple of sheets of newspaper taped flat to a cardboard
box at about six feet distance - this seemed to replicate the set up in the
maintenance manual. Not having a loupe I used a 50mm lens of a 35mm
camera. Question is, has it drifted since then or perhaps the 135mm lens,
my least used, was a bad one to adjust the screen with. I should have used
the 55mm or 80mm which I use most.

Any reason for picking infinity rather than a closer target?

For the ground glass screen I used a piece of glass and an oil stone. A
tedious job!

Pete


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