View Full Version : Measuring shims - inquiring minds

Steve Goldstein
15-May-2009, 15:21
For no very good reason in particular I measured the thickness of the shims between the front cell and shutter on my 90mm f/8 and 120mm f/8 Nikkor-SW lenses. To my surprise, both were 0.004" (100um). This got me thinking...

If the front cell is too close to the rear one, the spacing can always be fixed up with a shim. If the reverse is true (too much separation) it can never be optimized since shims don't come in negative thicknesses, at least the ones I can afford ;). I guess if I had an optical design where the cell spacing was really critical I'd make sure to manufacture such that a shim was always required. But maybe modern manufacturing techniques have gotten so good that it turns out the same shim thickness is always needed.

This is where the inquiring minds part comes in. Have you measured the shim(s) on your Nikkor-SW? If so, how thick are they?

Clearly I have too much time on my hands.....