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Ezio
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 16, 2004 - 01:45 pm: | 
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I've recently obtained a Super Ikonta (531/16) with a very puzzling focusing problem. The rangefinder is accurate, and tests with the ground glass on the film plane have shown that the camera is perfectly capable of being right on focus. However, when the lens are set to the real distance the photos (and the ground glass) are out of focus. In order to obtain proper focus, it is necessary to set the lens for a shorter distance than real (say, 1.2m for a subject at 2-2.5m). That is, the lens must be rotated more outwards than normal. This seems to be confirmed by the fact that the rotating front element which carries the distance marks appears to be "sunk" into the front standart, and when rotated to inf. the sign is nearly invisible. I suspect that the front lens might have been disassembled for cleaning, and re-installed in the wrong way. If so, how should I proceed? How can I remove the connecting arm which holds the whole element? Is it perhaps possible to solve this by removing only the front lens (this is hold by three small screws inside thiny holes) and giving it half a turn more? |
David Richert
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 18, 2004 - 11:42 am: |
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I show how to adjust an AGFA at http://www.davidrichert.com/AGFA%20rebuild/agfa.htm towards the bottom of the page. The Zeiss is a little more difficult but it's about the same. The difference would be setting the range finder to infinity at the same time. |
Marco
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 18, 2004 - 03:54 pm: |
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Ciao Ezio,
I am a little confused regarding the problem you are encountering:
Disregarding what the rangefinder says (it could be off), does the ground glass show a focused object (placed at infinity) when the lens is placed at infinity? Does this happen also for an object placed at 1m, with the lens at 1m?
If this doesn't happen then loosen the scale ring on the lens, turn the lens till you get a sharp infinity (for an object at infinity) and retighten the scale ring. If you can't get this to work then you could have a loose center or rear element...
Once you have the scale focusing right, readjust the rangefinder to match.
Ciao
Marco |
Ezio
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 20, 2004 - 11:30 am: |
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Grazie Marco,
no, the rangefinder is accurate, but the lens is not. That is: with a subject at 5m the rangefinder will say 5m but the ground glass will show out of focus. In order to get it into focus, I must set the lens at about 2.5-3m. The problem us either only the front element, or the entire lens mount. In the meantime I have acquired a very small scredriwer that will allow me to loose the front element anddo some test. Will report. |
Winfried
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 20, 2004 - 03:09 pm: |
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Usually front element focussing lenses are adjusted by turning the front lens element only and attaching the focussing ring accordingly. I found that most front element focussing lenses are shimmed (i.e. the entire lens is adjusted) such that to focus at oo you have to turn the front lens element just 1/2 turn or less from its end position (i.e. from the position totally screwed in).
On Super-Ikontas with a rotating prism rangefinder (i.e. with a rangefinder arm on the lens barrel) the rangefinder and the lens can be adjusted independently, i.e. the rangefinder adjustment will not change when you loosen the focussing ring and set the lens correctly. |
ezio
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, March 21, 2004 - 02:13 pm: |
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Thank you all - it worked. I describe the procedure because it may be of help to others: loosening the three smal recessed screws around the front ring (carrying the distance marks) allowes you to remove it. This exposes the front lens element. As Winfried says, this needed to be turned by half a turn from its end position. The rangefinder was not affected, and remained accurate. A 10 min job - if you know what you are doing. Incidentally, during the procedure I discovered that the paper/plastic envelopes photo labs use to give you back your 6x6 slides (transparent on one side, matt on the other) make an exceedingly practical alternative to ground glass. |
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