Home adapted Iskra 645/220 film

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ruben

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Although 645 Iskras have been around, the novelty (as far as I know) is the use of 220 film, for which the Iskra had to be custom adapted.

My adaptation started from a full working Iskra 6x6 bought from Vickentij Trofimov (Soviet Camera Store - Ucraine). The adaption consists of the following stages: (Kindly excuse my poor technical knowledge, and my English language limitations)

a) Dis-abling the film frame counter mechanism, in an educated manner. This includes extirpating the thin axis making holes to the film. And sealing the empty space left by the extirpation at the camera top and bottom. I have not found an educated way to do it, but fortunately, after 3 by-force-only surgeries at 3 different bodies, all 3 axis remain not broken and re-installable.

b) Designing an alternative graphic manual frame counter, and a manual graphic film advance counter. For an effective solution, i.e. a way that works acceptably fast enough, I have been experimenting schemes with my graphic program (CorelDraw). I hope some day I will post a self explanatory pic.

c) Sealing from light the camera chasis, further more. You will have to paint black ALL the chromish color parts of the back, the only exception being the film horizontal tracks above and below the square film exosure window.

d) Adding an extra pressure to the film pressure plate. This is easily achieved with the addition of 2 small rings, to be inserted between the film plate and the back's spring, around the the 2 screws attaching the film pressure plate to the back's spring.

e) Installing 2 frame patches (inserts) to transform the 6x6 square into 6x45 format. In my case, instead of the traditional way of inserting these metal parts between the bellows and the chasis, I glued the metal inserts to the square mouth, very close to the film path. The traditional way produce good and strongly attached inserts. My way produces weakly attached inserts, prong to extreme care when fidling with the rear lens compound. I was led to this way, since one of the screws attaching the bellows to the chasis, was impossible to unscrew.

Some surrounding remarks.
A) Light leaks.
Since I begun purchasing Iskras, (3 up to day) I have had light leaks. First I suspected the lens iris, then the bellows. But today I think I am smarter.

In my opinion the main suspects are both the 2 lower wheels at the bottom of the camera, and several points at the top body compound. Light entering to the top compound is prompt to reflect into the inside of the upper latch of the back and enter the film housing. Good treatment is to seal the back latches with foam, to paint black the inside of the chromish top housing of the camera, and to black-tape any hole inside the film housing, SPECIALLY the surrounds of the 2 lower wheels engaging the film, at left and right side.

B) In general, the Iskra is a very simple-mechanism camera, friendly to deal with, and amicable to surgery.

C) HOW TO REALLY SOFTEN THE FOCUSING MECHANISM.
The only known solution to this known desease has traditionally been clenaning the reels moving the lens forwards and backwards. But after doing it and lubricating, it has not produced to me a sensible result. Nevertheless I discovered a different way to soften the focusing knob. It consists in carefully unscrewing A BIT the 4 screws attaching the front side of the bellows plate. This screws are those seen surrounding the lens when you open the back, when the lens is collapsed.

Additinally you can also unscrew A BIT the upper screw among the 3 screws attaching the aluminium lens compound surrounding the lens. I am talking about the aluminium device with the stamped depth of field scale. In order to reach these 3 screws, of course, you will have to start dis-assembling the lens coumpound from its rear side: First, unscrew the inner ring surrounding the lens (this ring is not quite visible at first glance, but this is the one holding the lens to the lens compound), then the lens is released and the 3 screws visible. The one to be unscrewed A BIT is the upper one.
All these sensible and carefull un-screw actions have not produced me any light leak.

D) Back holed Iskras.
Two of my Iskras are back-holed. One is a 645 "export" model, the other a normal 6x6. Alongside with the perfect one purchased from Vickentij, which I transformed to 645, I have been working to improve the export holed model.
Surprisingly for me, the holed back, after further sealing measures, is indeed light-proof when using 120 film, and I find the holy way of advancing film quite straightforward.
The "additional measures" I took, consist in surrounding the space between the back red hole, and the film pressure plate hole, with plain cotton. And painting the cotton black.
In order to see the red hole when the camera is in case, I have holed the case too. And with the help of Prym buttons I made a kind of door, sealing the case hole at will.

Cheers,
Ruben
 
Thanks for the instructions. Now my Iskra focuses quite smoothly! The light leaks are a challenge aren't they?
 
ruben said:
In my opinion the main suspects are both the 2 lower wheels at the bottom of the camera, and several points at the top body compound. Light entering to the top compound is prompt to reflect into the inside of the upper latch of the back and enter the film housing. Good treatment is to seal the back latches with foam, to paint black the inside of the chromish top housing of the camera, and to black-tape any hole inside the film housing, SPECIALLY the surrounds of the 2 lower wheels engaging the film, at left and right side.

Cheers,
Ruben
Click to expand...


Yes, and besides the lower gear wheels, I advise everyone to open the back and give a 10 minutes deep look to all points of light communication between the top compound and the film housing, and also the fitting of the back to the body rails of insertion of the back.

Cheers,
Ruben
 
Ruben,
thanks for the tips. When you say unscrew the screws "A Bit", are you saying you leave them a little loose. My Iskra has a tight focus and I would love to loosen it a bit but I'd be worried of the screws falling out, I guess you could put some "leak lock" on them.

Also, have you any experience with the lens pivoting on its axis when the camera is open? Mine pivots front and back very slightly but just enough to affect the focus on the rangefinder.

I also have a frame spacing problem where some images overlap, I have heard this is a common issue, any ideas?

This is a valuable thread to those of us that use this quirky camera :), thanks.

Todd
 
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When I checked my Iskra, the four screws were all very tight and not all the same degree of tightness. I backed them off about 1/8 to 1/4 turn and then retightened them as evenly as possible, but not as tight as they had been. The focussing was much less stiff and two spots where the movement was sticking slightly went away. Although the focussing is still a little too stiff, it's possible to focus with one finger on the ring. Once I was satisfied with the movement, I put a tiny drop of clear nail polish on each screw to hold it in place. This wasn't really necessary, but I did it anyway. Removing the lens/shutter assembly was a bit fiddly, and I couldn't quite see what Ruben was writing about the screws, but it was a good oppurtunity to remove the old grease and re-grease the helical threads.
 
ON SOFTENING THE FOCUSING WHEEL.

Let's start from the beginning, and excuse me again for my limited technical knowledge and poor technical English.

Let's say that you are back in the sixties and bought your Iskra new from the factory with the right amount of grease in the helical thread (thank you, Victor), and every thing in the right position. Even then, the focusing wheel wouldn't be, in my opinion, as smooth as focusing a Japanese 50mm SLR lens from the same period.

Why?, because instead of all the intelligent design, the mechanical design of the focusing wheel is rather rough: it starts with the very small and uncomfortable knob on which you put your thumb. Kindly follow me.

From this dis-advantageous leverage position, only your thumb has to bear the resistance forward-backward movement of the lens, first, AND at the same time you are pushing the rangefinding mechanism that starts with the levers besides the lens, and climbs to the top camera compound, where there is a very unfriendly spring regulating the movement of the yellow patch mechanism, PRESSING AGAINST YOUR THUMB MUSCLES.

With all this Bible-long-like explanation, I am trying to say that even if you figuratively remove all the 4 screws around the rear lens, and the 3 screws visible inside the 'depth of field compound' once you remove the lens - even then, the focusing wheel will not be as smooth as a Japanese SLR lens focusing wheel.

Therefore, some measurable resistance in the focusing action is to be expected. It is very important to keep this in mind. What we are trying to do is to save the un-necessary resistance. Therefore we are trying to find a middle point.

This is a subjective middle point, a compromise between unscrewing as less as possible and obtaining an ACCEPTABLE degree of resistance. If you loosen a bit the 4 screws around the rear lens, it is logical to assume that you will have to check from time to time their situation.

VictorM. has done right, read his message. Therefore perhaps it is unnecessary to propose the following proceeding, for those who may want to try loosening these 4 screws only:

a) With the lens collapsed, open the back and unscrew the 4 screws TOTALLY.
Be carefull to perform this fidling with screws over a big foam, carpet, or any suitable secure environment, as screws are rather jumpy and you don't want to loose any one.

b) Then, loosen a lot the OUTER ring around the helical thread compound. This ring is the big one you see immediately bordering with the 4 screws.

c) In this situation, move the focusing wheel from 1m to infinity and vice versa several times, in order to gain the feeling of the best you can obtain concerning smoothness.

d) Then screw back the 4 screws, let say 3/4 of their total length and move again the focusing wheel. You should not feel a measurable difference. But from here you will start screwing the screws a bit and start feeling bigger resistance of the focusing wheel. The ideal is to reach a level of screwing as close to total screwing as possible, carrying a maximum of comfort for the focusing thumb action.

e) At some point you may find that the focusing action becomes abruptly stiff. Here you unscrew A BIT. If this point is within a full turn (12 analog clock hours) up to maximum possible screwing - then your results match mine.

f) Repeat the same method of trial and error for screwing back the outer ring [see b)]. Accordig to one my Iskras, this outer ring bears a small guilt for the stifness charge. Overall it is secondary, but un-harmfull to try.
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A more complicate but promising proceeding involves, in correlation with the abovementioned, softening also the upper screw among the 3, found inside the depth of field compound (I mean the housing over which the depth of field scale is stamped).

In this case there is no risk that this screw will continue to unscrew itself with time, as the lens compound prevents him to "escape".

For this proceeding, which involves dis-mounting the whole lens compound AS A WHOLE IN A SINGLE OPERATION (it sounds harder than it is in practice), follow my instructions in my first message and ask me any questions you may have, if you have.

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Regarding lens pivoting from their axis, IF I understand you correctly, I have this problem with one of my three Iskras, the one that is serving me for parts, because of this problem. But I say again, IF I understand you correctly. I have not tryied to solve this problem, and therefore I have no experience at all.

BTW, the Iskras are so cheap that it is not a bad idea to own a second one as back-up to enable yourself more self-confidence when trying to fix one.

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Concerning frame spacing problems. I understand from the very question that your Iskra has a working frame counter mechanism.
First I must say that I do not have studied this mechanism and therefore I cannot offer any consistent solution.

From what I have seen I can say that this mechanism relyies on several springs moving or pressuring a lot of gears, wheels and handles - and as an assumption I will not be astonished if an authoritave technician will tell that one or more of these springs went exhausted. This is just an assumption. I hope one day Russ Pinchbeck will start dealing with the Iskras...

But on the other hand, for my big surprise, I can comfirm that the method of the "holed" Iskras is very fast and straightforward, without any risk of irregular frame spacing.

From my two working Iskras, one works this way. At the begining I was suspicious that the hole may be a source of undesired light leak. Therefore I sealed more or less the hole surroundings, between the back and the pressure plate, and I have no leaks at all. (I have not tryied the camera before sealing it, perhaps it may have worked any way).

Therefore my practical advice is to buy a cheap holed Iskra for its back (and keep the worst body among the two as back-up).

For further safety and comfort with my holed Iskra, I holed the case too. Then you can insert a square cardboard between the back and the case, to seal the hole, and lift it just when winding.

I myself have performed a kind of top with additional leather and Prym buttons. But as this involves some tools, I offer the above suggestion.

Cheers,
Ruben
 
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Looking more closely at the winding mechanism, I discovered the 'toothed' wheel has teeth that are worn unevenly. Some of them are slightly shorter than others. This may cause the frame overlapping problem.
 
VictorM. said:
Looking more closely at the winding mechanism, I discovered the 'toothed' wheel has teeth that are worn unevenly. Some of them are slightly shorter than others. This may cause the frame overlapping problem.
Click to expand...

My Iskra II would wind up to the third frame properly, then continue on without stopping. This was due to one of the teeth being bent & half sheared off (there are two toothed wheels, one above the other. I think one counts the film spacing, the other controls the shutter block (?)). Anyway, since the tooth was already broken, I gently removed it. Now the camera takes 11 shots, but otherwise works fine.

If someone could make replacement toothed wheels (maybe that complete mechanism), I have a feeling the winding faults on any Iskras could be fixed.
 
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