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[disemjg]

I recently got a Crown 45 with a 127 Ektar; when I cleaned it up I noticed that the rear lens cell did not bottom on the cup seat. After adjusting the infinity stops, the lens was barely out of the body box, which was clearly wrong but that was where infinity focus placed it. The closer distances did not agree particularly well with the RF, but of course that did not really mean anything as the Kalart could be out of adjustment.

Luckily I had a spare Ektar rear cell in hand, and better yet it actually fit and bottomed in the shutter. Re-set for infinity, the lens now sits the expected distance away from the body box, and the RF is accurate at all distances.

Doubtless the lens/shutter combination was not original; someone swapped shutters or cells and did not notice or care that the rear cell did not fit correctly. I can wonder how many lenses out there have similar problems; the only tip-off here was the drastic difference in the infinity positon of the lens. Someone who did not know that it was not right would have happily used this combination, and I suspect that it would probably have even formed decent images. Judging from where the front standard was, it was probably about a 100mm FL. Just for grins I ought to go back and see what the angle of view was; maybe this had no effect on the FL or the AOV and merely resulted in an incorrect positon for the lens.

I'll be testing it shortly, and hopefully the replacement rear cell agrees with the front.

So, pay attention to cell seating, and if you see a gap question it.

[ This Message was edited by: disemjg on 2006-03-07 16:15 ]

[Les]

On a similar note, I was trying to figure out if one of my 1954 127mm Ektars that for some reason is in a late 1930s F. Dekel shutter, would slip into a Syncro-Compur shutter of the mid 50s. I found one of these shutters in my price range with a 203m ektar in it, and decided to tryi a front cell swap. Worked like a charm. The rear cell of the 127 ektar was a little tighter than I wanted to play with a tthe moment so I switched them back, but before I did I wanted to see what kind of image one gets with a 127mm front end and a 203 rear end..... the answer? Nothing... it won't focus at all. Gives a nice column of light though.


In one of his articles, Rudolf Kingslake talks about the advent of focusing by variable cell spacing, essentially changing the focal length.



Les