Hello friends,
I've been sitting at home with my sprained knee, so I had some time to adjust the RF in my Iskra. Well, it suffered from a strange thing - infinity setting in it was okay, and on the closer distances the rangefinder failed. When I did examine the lever with adjustable screw on it (on the right of the lens), I found that it has too much sideplay, so I unscrewed it to put a small washer under it. Surprise! The lever has a special profile, so it makes the rangefinder movement non-linear in respect of lens movement - a special pin follows the profile, so it's working like a cam. The end of this cam is split in two, and the split part responds to a close distances. If the camera is carelessly folded with its lens set, say, on 1 meter, the guiding pin can easily bend the split tail of the lever, making the short distance measurement very inaccurate. That was exactly my case. When I carefully straightened the bent part (with a wide screwdriver inserted in split), the rangefinder became normal - I checked it on 1m, 1.2m and 2m, and the numbers on scale were matching the tape measure to film plane. So I decided to post my finding here - I assume the problem can be quite a frequent one just due to RF construction, and I didn't see or hear anything about a separate 1m adjustment point in Iskra. Be very careful with bending - the bent part is thin, so it can break away if bent for too much (but the metal used on my cam is not brittle, I must say).
Just my 2c.
Cheers from Moscow, Zhenya
I've been sitting at home with my sprained knee, so I had some time to adjust the RF in my Iskra. Well, it suffered from a strange thing - infinity setting in it was okay, and on the closer distances the rangefinder failed. When I did examine the lever with adjustable screw on it (on the right of the lens), I found that it has too much sideplay, so I unscrewed it to put a small washer under it. Surprise! The lever has a special profile, so it makes the rangefinder movement non-linear in respect of lens movement - a special pin follows the profile, so it's working like a cam. The end of this cam is split in two, and the split part responds to a close distances. If the camera is carelessly folded with its lens set, say, on 1 meter, the guiding pin can easily bend the split tail of the lever, making the short distance measurement very inaccurate. That was exactly my case. When I carefully straightened the bent part (with a wide screwdriver inserted in split), the rangefinder became normal - I checked it on 1m, 1.2m and 2m, and the numbers on scale were matching the tape measure to film plane. So I decided to post my finding here - I assume the problem can be quite a frequent one just due to RF construction, and I didn't see or hear anything about a separate 1m adjustment point in Iskra. Be very careful with bending - the bent part is thin, so it can break away if bent for too much (but the metal used on my cam is not brittle, I must say).
Just my 2c.
Cheers from Moscow, Zhenya
