I-22 Question

[ZorkiKat]

Whilst it is possible that some I-22s are not focussing on infinity when they are locked, I can't see the distance scale being a proper indicator of this. I submit the pointer is just on a ring and has about the same mechanical relevance as a hubcap. If I was confronted with the absurd situation where pointer was "a few millimetres" out when the lens was locked, I would put my bet on the lock.


There is a strong implication here that you adjust your rangefinder to agree with the pointer on the scale, irrespective of where the lens is really focussed. I would really rather hear terms like "image at film plane" here


This says nothing or may equally mean the the RF is actually improperly adjusted. Indeed from reading the above, I suspect that that is very likely to be the case.


!!

Again, read the soviet repair manuals, if you could find them.

Why would it be hard to see why these lenses' infinity settings be slightly ahead of their locking position? Why shouldn't the infinity mark be trusted as the lens' true infinity position? The lens will continue to move beyond that and push the RF sensor tip even further back, affecting the RF's calibration greatly.

Those engraved distance marks should not be readily dismissed. The ones which I found (and there are many of them) mark the scales quite accurately. Use a separate rangefinder, and focus any of these lenses by their scales and you'll get properly focused images.

Before I knew better, I adjusted my first Zorki using what I thought applied to it. I thought that adjusting its rangefinder the way I adjusted my Leica and Canon cameras was enough. That by simply tweaking the RF port screw until 'infinity' lines up with the lens locked at infinity was correct. It wasn't.

My lens then was an Industar-22. It locked past the infinity mark. I adjusted the camera so that the infinity target lined up with the lens locked. But when I put a Summitar on the Zorki, the RF image failed to coincide when the Summitar was locked at infinity. It only meant one thing- the RF setting was past its correct setting. Looking at the I-22 aqain, I noticed that it (and many other I-22 I eventually got) actually locked at past its infinity setting.

When such a lens is used to adjust the camera RF's infinity setting any other lens which stops at its true infinity mark would not couple with the camera right. Even the I-22 in question would probably couple erratically.

 

[Nickfed]

Why shouldn't the infinity mark be trusted as the lens' true infinity position? .

Well actually, I trust my infinity marks implicitly. The reason why I do so is that they point to infinity when the lens is locked, or in the case of the i-50, comes to the end of its travel. Also in the case of the I-50, the reason why it does so is because that it is where I put it when I assmbled it.

As for the rest, well Maizenberg is not to hand and I'm off under the shower and to bed. So perhaps you might enlighten us eventually on the RF follower adsjustment, the degree thereof, the geometric implications that are consequent, the relevance in the result, what happens to the infinity adjustment at the other end, and how the poor ol'; I-22 handles this in a total travel of 2.886mm.

You can do it on a Zorki-6. That's the one I alluded to - the one with the swing back and the big follower.

It's all a dream isn't it?

 

[ZorkiKat]

As for the rest, well Maizenberg is not to hand and I'm off under the shower and to bed. So perhaps you might enlighten us eventually on the RF follower adsjustment, the degree thereof, the geometric implications that are consequent, the relevance in the result, what happens to the infinity adjustment at the other end, and how the poor ol'; I-22 handles this in a total travel of 2.886mm.

RF adjustment is described in great detail in my FED Zorki Survival site. Click on the link in my signature.

There's nothing there about the geometric implications and the like. I never bothered to find out what these where nor do I care for them. The official repair instructions say what's supposed to be done- they work, so why should I even question the wisdom of those who designed it? If it works, then that's all the relevance it needs. Why make life complicated with figuring the math and geometry of objects when these have have already been competently figured by those who knew what they were doing? :bang:

To quote Maizenberg from his book, Repair and Design of Russian Cameras:
(describing infinity adjustment using the RF port screw): "Slightly turn the screwdirver and find the slot of the shaped screw 8 fig 157. Rotate the screw in one direction or the other depending on the position of the second moving image. If it does not reach infinity, tighten the screw; if it goes too far, loosen it. This is done until both images (moving and still) of the indefinitely distant object coincide.

"After that check the rangefinder at the 2-4 m distance. Using a measuring tape, measure 1, 2, and 4 metres from the back of the camera and draw a cross-line target on a piece of white paper. Focus the rangefinder on this target and check the readings of the lens range scale. If they deviate from the actual values, the rangefinder is still not adjusted. In that case, continue ther range by turning the cam 12 fig 127 [the pivoted sensor tip] no more than 3-5 degrees. If the reading exceeds the actual distance, turn the cam up; if it is less than the actual distance,
turn the cam down.
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"Turn the cam by 3-5 degrees in the proper direction and adjust the rangefinder again focusing on an infinitely distant object and an object 1 metre away from the camera. Repeat that until the rangefinder readings for infinity, and 1, 2, and 4 metre become equal to the lens range scale readings. Permissible deviation on the scale is 0.5-1 mm for 1, 2, and 4 metre distances to the object; the readings should be absolutely identical for the infinitely distant object. "
pages 135 and 137.


And BTW, this is the way its done with the Zorki-6 too. My two Zorki-6 focus with competence now because of this manner of adjustment.