Andrea Gazzoni
12-Nov-2014, 11:12
Hello, I have an Apo Nikkor 760mm which seems impossible to focus, the image on the ground glass is blurry.
I suspect it was modified at some stage in the past.
If I unscrew the front and rear elements, here is what I find:
1) front cell: the optical unit is simply placed inside the barrel, once you lift it out, you find that silver spacer I'd say about 6-8mm high. I've thought of removing the spacer, but in that case the optical unit would sit too low and there would be a gap between it and the outer retaining rim (the one with the letterings that closes the front cell).
https://dl.dropboxusercontent.com/u/80149550/front%20cell_rid.jpg
2) rear cell: since in its closed position it doesn't focus, I've tried loosening the rear element by small bits before, then by 2-3 complete turns, no big changes.
unlike the front, this element is screwed inside the barrel, so by turning it you change the distance between the elements. once completely unscrewed and pulled off, I find a black spacer above a gold color collar which requires a spanner wrench or similar tool to be moved
https://dl.dropboxusercontent.com/u/80149550/rear%20cell_rid.jpg
I was wondering if anyone with such lens could look inside their copy and tell me if there's any visible difference.
Also any suggestion for basic troubleshooting is appreciated. So far I've tried moving the rear element a bit backwards, but to no avail. Also tried to reverse the front cell, but it doesn't fit.
thank you in advance
Andrea
I suspect it was modified at some stage in the past.
If I unscrew the front and rear elements, here is what I find:
1) front cell: the optical unit is simply placed inside the barrel, once you lift it out, you find that silver spacer I'd say about 6-8mm high. I've thought of removing the spacer, but in that case the optical unit would sit too low and there would be a gap between it and the outer retaining rim (the one with the letterings that closes the front cell).
https://dl.dropboxusercontent.com/u/80149550/front%20cell_rid.jpg
2) rear cell: since in its closed position it doesn't focus, I've tried loosening the rear element by small bits before, then by 2-3 complete turns, no big changes.
unlike the front, this element is screwed inside the barrel, so by turning it you change the distance between the elements. once completely unscrewed and pulled off, I find a black spacer above a gold color collar which requires a spanner wrench or similar tool to be moved
https://dl.dropboxusercontent.com/u/80149550/rear%20cell_rid.jpg
I was wondering if anyone with such lens could look inside their copy and tell me if there's any visible difference.
Also any suggestion for basic troubleshooting is appreciated. So far I've tried moving the rear element a bit backwards, but to no avail. Also tried to reverse the front cell, but it doesn't fit.
thank you in advance
Andrea