Voigtlander Skoparex 3.4/35: delight and infinity fix

[alex ph]

What a gem the small Voigtlander Skoparex 3.4/35 is. Colours, sharpness, pop are enjoyable. It also guides my camera very well in almost all the cases to preserve sky in the dynamic range. Pretty much film-like experience. Taken with Sony A7.

#1 Af f5.6, unprocessed beside resize


#2 At f5.6, autocontrast


#3 At f5.6, autocontrast



I wish I could use the lens' full potential also in close distance. But here is the closest I can reach.

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My copy leaves a good half of the distance scale "useless" past infinity while the MFD on Sony DKL mount is around 2.5 meters which is almost a mid-range. What is even stranger, a Skopar lens (intended for the same camera) does not reach infinity being put on the same adapter. So, it is not the adapter but the adjustment of the lenses to blame.

Here comes my question, is it possible to adjust the distance range inside the lens? What is your experience? And how do different Voigtlander lenses behave with your DKL adapter?

UPD: Added "infinity fix" to the post title, in case someone else searches for a solution.

[Ultrapix]

I did love that lens in the film era, especially for colors, and contrast compensation.

It's certainly possible to adjust the focus; if I remember well, you should unscrew the whole front part, and then you should be able to understand what to do. If not, drop a pic.

[calvin83]

I have tired Color-Lanthar and Septon on my DKL adapter. Both focus to infinity at or very close to the infinity mark of the lens.

[alex ph]

Ultrapix and Calvin, thank you for your quick reaction.

I easily unscrewed the Skopar 2.8/50 upper ring which discovers 3 (retaining?) screws and a small hole (on the right side of the lens shot) where I can see another screw when I turn the focusing ring. Should I operate this last screw in the hole to release the infinity stop and then fix it back once infinity is adjusted?

#1



As for the Skoparex 3.4/35, the outer ring does not unscrew, even with a strong effort in a latex glove. I guess, the reason is, as compared to Skopar, it has 3 tiny screws on the side surface of the ring which retain it. One of them is seen just above the word 'Germany'. It is not fully reachable, as this is the max distance to which the lens goes up when focusing. How to release the ring in this case?

#2


But maybe there is another solution. In general, Skoparex has a more complex construction and focusing adjustment might be controlled differently. Here is the bottom of both Skoparex (left) and Skopar (right), with an additional group of 3 screw in Skoparex, one of which is marked with a yellow colour. Could that be for distance, or for diaphragm adjustments? I don't dare touching any screw without a clear idea about what it does, as it risks to ruin this nice lens functionality.

#3

[Ultrapix]

Don't touch the yellow screw. You have to remove first the focus ring, you should find the screws under the thin plate retained by the two screws. Once that you have stripped the front part like in your Skopar, you have to untight the 3 screws when the focus is in a mid range, turn the ring to the far end, lock one screw only and find the infinity. Then unscrew again, move the ring to infinity, and lock everything.

[alex ph]

Thank you very much, Ultrapix, for your suggestion! I tested your advice wth Skopar and it worked fine. Now I have a perfect infinity fit of the lens distance scale on DKL adapter. That really changes the feeling.

The Skoparex does not seem to be an easy lens for adjustments. I unscrewed the two retaining screws of the focusing "beauty" ring, just to discover that it hides nothing. I expected to find a kind of slot giving access to the tiny screws holding the top part of the body. No, the behind is just flat metal surface, and I still have no access to the screws, as they pop only at half from the focusing ring border.



That annoys me, as I wouldn't open the bottom part of the lens, with its fine aperture and distance scale springs which must jump out immediately.

[papasito]

Voigtlander made very good lenses.

The 35/3,4, 50/2,8, 135/4 are very good lenses.

The 50/2 and the 90/3,4 are better.

And the 40/2 Skopagon is the gem of the bunch.

The 50/2 8 lanthar, the zoom, the 200/4 and the 300/5,6 never liked me so much.

The 135/4 with the portrait lens is fun to use.

[Ultrapix]

[alex ph]

Unfortunately the margin is too small to reach the screws with a screwdriver, as the angle remains too acute. I searched in ebay BIN lists for another copy which is photographed in a position of the distance scale close to 1m, so that the helicoid is in its upper situation. Here it is, exactly as mine, with the side screw seen only at half.



I can hardly imagine that the lens requires a full disassembly to fix infinity, while all others I tried (2.8/50, 4/28, 4/135) offer different ways of an easy access to the front retaining screws via dismantling of the top housing part.

Dear fellows, if you have any idea, please share your hints.

[Ultrapix]

Well, I still think that you simply have to unscrew the whole front part. It's obviously stuck, but that is the way, IMHO. But please wait for someone's else opinion.

[alex ph]

I tried to do this with the tiniest screwdriver (0.7mm) and managed only to turn the screws a fourth of turn. When the screw head reaches horizontal position, the move is no more possible, as the screw hides too deep under the focusing ring. Sigh!

[Ultrapix]

[stevemark]

[alex ph]

Thank you again Ultrapix for your suggestion and Stephan for the confirmation. I finally managed to unscrew the top of the housing! That was at a price of a partly broken tiny screw, even though everything keeps in working condition.

This lens has a strange construction. The two screws serve to prevent the uper ring... from falling down. Also from lifting up, for sure. But the ring screws down as deep as out the edge of the inner thread, so at one point the ring slips down and freely wobbles inside the focusing pit. While the beauty ring is not a simple thin plate as many other lenses have. The lens' name is engraved on a thick copper part which must be unscrewed in the same time as the upper housing ring. I presume a dedicated rubber tool could help a lot. But it must have the exact size of the beauty ring because of the convex form of the front glass.

When both parts are unscrewed, three screws get accessible, and infinity adjustment is the same as in other Voigtlander lenses.



The screws are not visible in this shot, covered by the bold convex glass. But they are accessible with a thin screwdriver.

Now the optical infinity on DKL-Nex adapter fits to the infinity mark on the focusing scale. That changes the MFD to 1m or so, quite a difference.

#1 WO at MFD


#2 WO at MFD


I am aware there is another (later?) version of the lens, with MFD 0.4m. That must be an even more pleasant option.

The lens is a joy to use, and simple BW conversion is very pleasing.

#3


Stopped down, the lens copes well with difficult light conditions, and contrast pushing nicely preserves colours.

#4

[alex ph]

Leaving here a record for memory concerning different Voigtlander Bessamatic and Kodak Retina lenses I opened to readjust their infinity for digital use on DKL adapter. All lenses have the same way of adjustment: untightening three screws under the unmounted top part of the housing while the lens is set to actual (optical) infinity, then turning the focusing ring to infinity position and tightening back the three screws (thank you Ultrapix). The main difference in all lenses is the way you reach the screws.

Voigtlander Skopar X 2.8/50 - the easiest to open: simply unscrew the upper part of the lens housing, if necessary gripping it with a latex glove for the first, tighter move.

Schneider Curtagon 4/28 - almost as easy: first unscrew the beauty ring with the lens name using a special rubber tool or a latex glove and take off the freely moving upper part of the housing (which is also the hood).

Schneider Tele-Xenar 4/135 - quite easy with a screwdriver: focusing on MFD (4 meters) reveals three tiny screws on the side surface of the lens housing. Unscrew them and then unscrew the whole upper part of the housing together with the front glass. Fixing infinity requires several iterations of screwing back and unscrewing the upper part with the front glass to fix infinity, but its is not very much annoying.

Voigtlander Skoparex 3.4/35 - the most sophisticated: focus on MFD (1m in my copy) to lift the upper part of the housing as high as possible to reveal at half tiny side screws. Using the thinnest watch screwdriver (I used two, 0.8mm and 1mm) turn the side screws as much as possible, then try to move the upper part of the housing in both directions. It moves a bit thus leaving slight gain for lifting the top part of the housing even higher. Unscrew again, pressing against the focusing ring, move the upper part, repeat several times and be patient, as both screw and screwdriver heads easily degrade with a stronger effort. At one point the upper part lifts enough for the tiny screws be fully accessible beyond its edge, so you may unscrew them without obstacles. Then unscrew the upper part of the housing together with the beauty ring. If you use a latex glove or a rubber tool that makes the operation easier. After completing all these PITA moves, I thought it could be possible to go just as easily as with Curtagon 4/28 and to simply unscrew the beauty ring. The problem is the bold convex front glass which covers the retaining screws that you need for adjusting infinity. If you only dismantle the beauty ring, you have a straight angle to operate with a screwdriver, while with such a bold glass you need an inclination. So dismantling the upper part of the housing seems mandatory. When both the beauty ring and the upper part of the lens are unscrewed, you reach the three inside screws to fix infinity. After you finish, put the beauty ring on and screw it down, then put the top part of the lens and screw it down too until the tiny screw holes are at the lowest fully accessible position. Put the screws and screw them in at 2/3 or 3/4 leaving the upper part moving. Then repeat the adjustments to fix the top part deeper and screwing the screws inside. That's it. There might be a better, more conventional way to open the lens, but I did not figure it out.

As a matter for discussion, it's rather counter-intuitive that lenses destined for the same camera, like the Voigtlander ones, may have so different infinity settings. While Skopar was merely touching optical infinity on DKL mount, Skoparex had infinity already in the middle of the scale, leaving a good half of focusing move past infinity. That may be in some way explained by the work of the original camera focusing mecanism, and still surprising.

[stevemark]

[alex ph]

That sounds really interesting. Even though some kind of check and adjustment should have existed in photo production before the WWII, with the most heterogenious assembly of shutters and lenses on folder cameras. Later pre-sale rangefinder adjustment must be passed in production facilities too.

What makes me think more of focusing mecanism other than of adjustment errors in case of Skoparex and Retina lenses is the fact that both Schneider Tele-Xenar and Curtagon also had infinity reach on DKL adapter different from the on-lens scale. In the same time your Skoparex seems to have a similar past-infinity 'reserve' with mine. While Calvin reported his two 50mm lenses having the same infinity set as the 50mm Skopar I have.

I haven't taken notes of the original infinity reach of all the four lenses I opened and readjusted. But maybe someone having several DKL lenses of various focal length could add more info to this regard.

[calvin83]

I don't find an infinity issues with any DKL lenses I have tried from Rodenstock/Steinheil/Schneider/Voigtlander with my Yeenon adapter combo.

[alex ph]

Also wide angles has the correct infinity setting? I could think you have an especially precise adapter. But my experience with sensibly different infinity settings on the same adapter breaks the hope.

Back to the inexplicable...

[Vox]

Hi, Sorry to resurrect this thread. I was trying to remove the aperture ring from my copy of Skoparet 35/ 3.4 to use with my DKL to Fuji-X adapter. I was successful in removing the screws from the flange and was able to remove the aperture ring.

The issue is that the rings dislodged from their position and I've been trying to assemble the lens back but am not able to fit them all together and was looking for some guidance.

#7 Is a pic of the lens and the parts that have fallen out
#6 Is a brass half ring with a notch at one end. I've assumed that the notch needs to align with the piece below. I've done that in pic #5
#4 is a pic of a part that I have no idea what to do with - any pointers?
#3 shows a brass ring with some notches at one end - I'm assuming that the notches need to align with the gears in pic #6 - is this correct? What does the hole highlighted in red need to align with?
#2 is the aperture control and the notch aligns with the notch on the lens to control the aperture. What does the hole need to align with?

Appreciate any help I can get. As you can see I'm quite the newbie to putting together lenses


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[visualopsins]