Iskra rangefinder adjust

[wupdigoj]

Hello. I am new in this forum and my favorite cameras are and Iskra an a Retina II. The first one is actually made out of parts from an Iskra I and an Iskra II. The camera works well, but I noticed that close focus pics were (slightly) out of focus. I checked the rangefinder, and the only way I found to adjust BOTH infinity and close focus is by screwing fully (or nearly) the little screw near the lens assembly (you now, the one to adjust the rangefinder horizontally). In that way, I can adjust the rangenfinder by turning the mirror for example, BUT, I can only focus the lens down to 1.2 m or so, because of the little screw screwed fully (it is difficult to explain, but there is a piece which prevent the lens assembly to go further, if the screw is fully in). I can live with it, but it could be nice to be able to use the full focus ranging. Any ideas?. Excuse me for my poor English. Thanks in advance.

(I have just noticed there is also a "repair" forum. I don't know if it could be better to post there??)

Javier

 

[ruben]

Hi Javier,

The first thing I would check with ANY rangefinder camera is what the lens is telling me. I mean to attach a Medium Format split image screen to the back of your Iskra, taking care that the borders of the screen are on the FILM path, and the mate side of the screen is pointed towards the lens.

Then I will rotate the focusing ring to infinity and see on the screen, with the help of a great great magnification lens if I have a sharp image, or what.

I will repeat the same proceeding with the minimum distance, and see what I get.

From this point onwards we can start talking about rf alignment. The principle is that rf alignment is not to blindly show what the camera is supposed to do, but what the lens is showing in fact.

Of course that a lens alignment not allowing to achieve infinity sharpness is due to be corrected. But again and again, the lens first, the yellow patch afterwards.

Cheers,
Ruben

 

[wupdigoj]

Hi Javier,

The first thing I would check with ANY rangefinder camera is what the lens is telling me. I mean to attach a Medium Format split image screen to the back of your Iskra, taking care that the borders of the screen are on the FILM path, and the mate side of the screen is pointed towards the lens.

Thank you for your answer, Ruben. This is exactly what I have made, well, not quite: I use an old film with a piece of scotch (spelling?) tape, a hole in the back paper, and I peep thru the window in the back (I have one back with a window just for this). For checking the infinity focus I use a 35 mm reflex with a 200 mm lens, and for near focus a computer screen as target: when I can see the pixels, the focus is right. I use a 12 mm telescope eye piece as a loupe. If the focus (and the rangefinder) at infinity is correct, when I get sharp focus at 1m, the rangefinder is way out. I will keep on checking.

By the way, the lens in the iskra is a real gem!.

Javier

 

[ruben]

Thank you for your answer, Ruben. This is exactly what I have made, well, not quite: I use an old film with a piece of scotch (spelling?) tape, a hole in the back paper, and I peep thru the window in the back (I have one back with a window just for this). For checking the infinity focus I use a 35 mm reflex with a 200 mm lens, and for near focus a computer screen as target: when I can see the pixels, the focus is right. I use a 12 mm telescope eye piece as a loupe. If the focus (and the rangefinder) at infinity is correct, when I get sharp focus at 1m, the rangefinder is way out. I will keep on checking.

By the way, the lens in the iskra is a real gem!.

Javier

So we do know that the distance wheel is accurate, and the problem is in arranging the yellow patch for short distances.

I don't know by now this adjustment.

But I have a small question. When you tested your lens for infinity, did you pick an object, let's say a building, far enough from you - let's say 200 meters ?

Cheers,
Ruben

 

[wupdigoj]

But I have a small question. When you tested your lens for infinity, did you pick an object, let's say a building, far enough from you - let's say 200 meters ?

Yes. In fact the lens is remarkably sharp at infinity. I checked it using an airport lights and a communicatiosn tower at aprox. 5-6 km. Moreover, I have used a telephoto lens in a reflex camera that I know its focus is accurate: you look from the viefinder of the reflex camera to the lens of the iskra, with the shutter open and a few pencil marks in the film. Both lens at infinity. If you see the lines sharp, then the focus is correct. I have found this method, with a split prism in the focussing screen, more accurate than the previous. This night I will try to adjust it again. I have another rangefinder from another Iskra. Perhaps changing it?.

Thank you

 

[wupdigoj]

O.K., finallly I did it!. Comparing the rangefinder assembly in the camera and the spare one, I noticed the divergent element in the viewfinder was mounted in the wrong position (inside-out, so to speak). I never dissasembled it, so it must be another amateur trying to clean it or something. Now the rangefinder works well, and it is very accurate. I wonder if the softness of my camera at f:4 is due to this issue. I will check. Regards, and thanks Ruben for your help.

Javier

 

[ruben]

Great !,

But now that you have learned something new, kindly teach it.

What do you mean when you say "the divergent element int the viewfinder" ?

Cheers,
Rub en

 

[wupdigoj]

Great !,

But now that you have learned something new, kindly teach it.

What do you mean when you say "the divergent element int the viewfinder" ?

There are two square windows in the iskra, one of them just in from of the eye piece. From the hole you look thru, you find a convergent lens, then the beam splitter, and then a divergent lens in the external face. This divergent lens is supported by a metallic frame with three screws. I mean this lens. The frame was mounted in the wrong way, the intended outer face of the lens to the inside (I beg your pardon if this is not very clear: I do have difficulties to express myself in English). I just unscrewed the frame and mounted it correctly.

Regards

 

[ruben]

Great !,

.........(I beg your pardon if this is not very clear: I do have difficulties to express myself in English)......
Regards

Ningun problema senor, el subscribiente nacio en Buenos Aires. My Buenos Aires querido....🙂

In some time I will have to rearrange my Iskra 2 rangefinding adjustment from scratch, so then we may practice a bit of Spanish. Although there is one little problem. From all what I have read about Photography in its technical aspects in the Spanish language, I rather go lost with the specific terms of parts. In fact I go lost with them very much in English, and I don't touch any Windows converted to Hebrew.

Quite a gitano !

Cheers,
Ruben

PS,
Alguna informacion sobre Beniliam ?

 

[wupdigoj]

Ningun problema senor, el subscribiente nacio en Buenos Aires. My Buenos Aires querido....🙂

Encantado de saberlo <img>. Tengo varios primos en Buenos Aires.

In some time I will have to rearrange my Iskra 2 rangefinding adjustment from scratch, so then we may practice a bit of Spanish. Although there is one little problem. From all what I have read about Photography in its technical aspects in the Spanish language, I rather go lost with the specific terms of parts. In fact I go lost with them very much in English, and I don't touch any Windows converted to Hebrew.

I am at your service. After this problem, Iskra's rangefinder just don't have any secrets for me 🙂.

Quite a gitano !

Cheers,
Ruben

PS,
Alguna informacion sobre Beniliam ?

Quien es Beniliam??

Regards

 

[Robert Davis]

Javier,

I recently replaced the lens on my Iskra 1 . Ruben's old post on a related subject was very helpful (thanks Ruben!) I'm not sure if the "new" lens came from an Iskra 1 or 2 but I encountered some problems simlilar to your's. I had to back out the rangefinder adjustment screw almost all the way in order to set the infinity focus. After making this adjustment and checking with a groundglass and loupe, close range subjects would only come into focus on the far left side of the focusing square in the rangefinder window. If I adjust the screw to "center" the area of focus in this situation, the infinity setting is slightly off. Like your experience, if I focus down to 1m, the lens extends too far and slides out of its track causing it to jam. I'm very careful to not focus too closely.

Before mounting the new lens, I did take the oportunity to clean the helical gears by removing the ring with the distance scale from the main barrel. I discovered that it is a bit difficult to reposition them correctly. It took many attempts to get them aligned correctly. In the process of doing that, I realized that the old scratched lens with shutter problems was re-assembled by someone incorrectly. It seems that it was off by a couple of threads on the helical. Its possible that I am still off by a thread on the new lens. Otherwise, do you think the internal rangefinder pieces you mentioned previously could be out of alignment?

 

[wupdigoj]

Robert, I will try to explain it with my broken English.

As Ruben said, there are 2 problems here: FIRST, adjust the infinity focus, and second, adjust the rangefinder. For the first, put a ground glass or something similar in the film reels, use a distant target and a loupe, and put or replace shims between the lens assembly and the helical until the lens is focussing correctly at infinity (lens at f3.5, shutter open at B).

Now, to adjust the rangefinder. First, put the screw in the lens assembly (the one you used to adjust the focus), in a medium position. Put a target (a newspaper could do) at 1 m or a little more from the camera. Focus the lens at this target using the ground glass. NOw, you will have to adjust the rangefinder for this distance, if the patch and the viewfinder image don't coincide.

Remove the top cover of the camera (if you don't know how to do this, please ask). You will see that in the rangefinder assembly there is a "hole" in the left (seeing from the rear of the camera) revealing a screw. Moving this screw will move the patch both in a diagonal fashion (i.e. horizontally and vetically). Move this screw until
the patch and the image coincide horizontally. If you cannot reach this coincidence, you will have to move the mirror also, please ask. Now, adjust the vertical with a tiny screw near the mirror, in the upper right part of the rangefinder.

Next, using a distant target, adjust the rangefinder for infinity BUT using the screw in the lens assembly, not the one in the rangefinder. This adjustment will disturb the close adjust, but not much. Readjust the close focussing, and iterate this procedure until both infinity and close focus are O.K.

Hope this helps. Please ask if you need further details. Please, if you try this post your results.

Javier

 

[Robert Davis]

Making Progress

Making Progress

Javier,

Thank you for your detailed instructions. I finally found some time to work on the Iskra. I had to reset the helical focusing ring and lens assembly to get the correct infinity focus. I have gotten as far as you have described here in your post:

"As Ruben said, there are 2 problems here: FIRST, adjust the infinity focus, and second, adjust the rangefinder. For the first, put a ground glass or something similar in the film reels, use a distant target and a loupe, and put or replace shims between the lens assembly and the helical until the lens is focussing correctly at infinity (lens at f3.5, shutter open at B).

Now, to adjust the rangefinder. First, put the screw in the lens assembly (the one you used to adjust the focus), in a medium position. Put a target (a newspaper could do) at 1 m or a little more from the camera. Focus the lens at this target using the ground glass. NOw, you will have to adjust the rangefinder for this distance, if the patch and the viewfinder image don't coincide."

Now I need to ask for instructions about removing the top cover on the camera body.

Thanks,

Robert

 

[wpb]

This is a quote from a p.net post:

"The removal of Iskra top plate is easy. First, remove the winding knob by carefully unscrewing its central screw with a special key or tweezers. Then remove the camera back and locate two rather crude-looking screws in the upper parts of film compartments. Unscrew both of them. The third screw keeping the top plate in place is under a plate on accessory shoe. Unscrew the small stop screw on accessory shoe platform, and gently remove the small spring-loaded plate with a dental pick or some small hook. You will see the screw under it, unscrew it and the top plate should come off easily. Don't overtighten the screws when reassembling, the metal is rather soft."

(I think) I found a single aluminum spacer between the shutter/lens assembly and the focusing helix... it is the one with the two notches in it, correct?

 

[Robert Davis]

Thanks for forwording the p.net post. The procedure sounds simple enough. Hopefully, I can find some time tonight to work on the camera. Unless I am mistaken, I don't recall seeing a spacer between the shutter/lens assembly and the focusing helix?

 

[wpb]

I'm actually "shadowing" you as I'm also working on my Iskra. I (finally) tracked down my light leak(s) on my Iskra, so now it is on to the the lens. The focusing helix and focusing lever I removed and cleaned. The grease had become quite firm but was cleaned without much problem. Tonight I'll (try) to collimate the lens and then lastly adjust the rangefinder. Maybe I'll take some pictures tonight while I have it open so we can all be on the same page and offer some guidance for anyone else who undertakes this project in the future. The above information about adjusting the rangefinder is excellent, I'll have a go at it soon and report back. This project has been well worth the time. Thanks to all involved.

 

[wpb]

duplicate post.

 

[Robert Davis]

Collimating the lens was quite a challenge for me -- an exercise is "trial-by-error." My helical had some old dried out green colored grease which must have been quite viscous when fresh. The grease I tried from MicroTools didn't quite do the trick as a "dampening grease." I decided to try dielectric grease. Obviously conductive properties are not required but the gel-like consistency seemed about right. The special lubrication is not need as much on the helical as it is on the two flat surfaces between the front standard mount and the focusing ring. That's where the viscosity is needed most.

Robert

 

[Robert Davis]

Success!

Success!

Using Javier’s instructions, I succeeded in accurately adjusting my Iskra rangefinder for both distant and close subjects.

The instructions quoted above from the p.net post, however, may have been formulated for an Iskra2. There was no screw under the hot shoe on my camera. One of the two screws on my Iskra1 camera is accessed by removing the top film spool lug inside the film compartment on the upper left side. It is visible while the lug is in place but cannot be removed directly without removing the spool lug. The other screw sits underneath the winding knob and is plainly visible and accessible once the knob is removed. I removed the central chrome plated two-holed screw by making a spanner tool out of vise grip pliers and two brads.

The Iskra is a great camera and well worth all of the time and effort I put into it. I greatly appreciate all of the help I have received along the way.