Lens Jos Schneider & Co Kreuznach Xenar 4.5/10,5cm

[svetoklik]

I have Kodak duo 620 camera for 6x4,5 Cm format, but front magnifier glass for focusing is missing.
Also have Jos Schneider & Co Kreuznach Xenar 4.5/10,5cm lens with shooter that opening 125 on all chosen speeds.
Assuming that folder lens 10,5 cm is for 6x9,5 Cm format it will be possible to mount this Xenar on to Kodak duo with proper distance from the rear glass to the film.
Diameter of the lens is about to fit dimensions of kodak plate.
Does someone know this distance?

 

[OAPOli]

For these lenses, the shutter mount to film plane distance is approximately equal to the focal length. Since the Kodak Duo uses a 7,5cm lens, the 10,5cm lens in the same spot will be way too close and won't focus on anything. And generally speaking, lenses are collimated to infinity to a fraction of a mm in the position. So swapping two lenses of the same focal length might not even work.

 

[svetoklik]

Thank you for your answer. I know that swapping lenses without adjusting register distance from rear lens to the film is not possible. I have managed to adopt some lenses for my digital movie camera but there where documentation.
My question is does somebody knows distance from 10,5Cm folder lenses to film plane?

 

[Dan Daniel]

In another direction, there were 7.5cm Xenars used on some Zeiss 6x6 and 6x4.5 folders. These would use front element focusing.

I would start with 3 cm more distance than for the 7.5cm Xenar and test from there with the 10.5 cm.

Wait, didn't the Duo 620 use focusing of the lens board, not front element focusing? If so, Rolleicords also used 7.5cm Xenars. I bet you could do a simple swap.

 

[svetoklik]

That is right Dan, there is no lens rotating on to Duo 620, but here is missing lens on the top and therefore no focus nowhere to be found.

Does somebody know what is the dioptry of that lens on the top?
Duo 620 is great handling camera, everything is under sight. fingers and purpose to make photography.
Just joy for the use. Good old american way.
If someone is under hand 10.5 cm lens for 6x9 cm format and have a moment to measure registar distance from film plane to the back of the lens?

Open helicoid on the rear of Kodak anastigmat 3.5 &,5 cm lens, very nice and honest for maintenance.

 

[OAPOli]

Since you have the lens, you should try to measure it directly. This is a specific measurement, which can vary ~0.5mm between samples.

Are you saying the shutter doesn't open on B or T? Maybe you can transfer the lenses onto the Kodak shutter?

 

[svetoklik]

For these lenses, the shutter mount to film plane distance is approximately equal to the focal length.

That is correct for the most lenses for folder cameras except for the formats like 6x4.5 cm as is on to Duo 620/ It is soorter about 1 cm compared to other camera with the same 7,5 cm focal length.
Later I will measure registar distance on to one 19,5 cm camera, but it will be very difficult to put that Schnider Xenar 10,5 cm that I am checking now.

 

[Dan Daniel]

The lens on the Duo 620 in your case is a Schneider Xenar lens. They just had it re-labeled. So find a Xenar from this period and see if it can either be fully swapped or if the front element will work.

The shutter is a Compur, which has standard lens mount threading and spacing for this era. Again, a 7.5cm Xenar from a Rolleicord or Zeiss would work. A Tessar would also work, I bet. In all cases you may need to move the shutter block forward or back, and they used shims around the base of the shutter for this purpose.

And a 7.5 cm Xenar does not care about the film format. Its distance can change due to shutter and helical issues, but not optical changes for different formats of film. Go ahead, find a Xenar or Tessar and see what happens.

As an aside, the basic camera was made in Germany, not America

 

[OAPOli]

The lens pictured in post #5 is a 7cm. These are uncommon. You can check if it's a triplet or a Tessar type by counting the reflections of the rear group.

OP, I don't understand what you are trying to do.

Measuring focus distance isn't trivial. I've made some 3D-printed parts to attach the lens to a m42 helicoid, and attach that to a tube with a piece of ground glass on the other end. Find infinity then measure the length of tube + helicoid extension.

 

[BrianShaw]

I'm aware that you've been working this problem for a couple of years. Unless you have an emotional bond with this camera or really want a project, it might be more effective to buy a replacement that is complete. The Duo 620 seems to have increased in value over the past few years so not an inexpensive option. If you do, a Series II might be worth considering as the self-erection system is a bit mroe robust. Whatever you do, good luck as it is a very sweet camera to use and the output is very good (once mastering the primitive shutter release system).

 

[BrianShaw]

The lens pictured in post #5 is a 7cm. These are uncommon. You can check if it's a triplet or a Tessar type by counting the reflections of the rear group.

OP, I don't understand what you are trying to do.

It seems that the goal is to replace the missing lens element and take pictures. Here is an example of complete lens:

Vintage Kodak Duo Six-20 620 Art Deco w. Kodak Anastigmat 3.5/7.5cm lens | eBay

Lens: Kodak Anastigmat 7.5cm f/3.5. The lens Kodak Anastigmat 3.5/7.5cm provides good quality images. Film: Uses 620 roll film. It was produced in various versions, with different lens and shutter combinations.

www.ebay.com

 

[Dan Daniel]

The lens pictured in post #5 is a 7cm. These are uncommon. You can check if it's a triplet or a Tessar type by counting the reflections of the rear group.

Oops, yes, 7cm, not 7.5 cm.

Early Zeiss folders have 7cm lenses. Like here-

1936 ZEISS-IKON SUPER IKONTA A, 6x4.5, Tessar lens, CLA'd, Freshly Ser

Cleaned, Lubricated & Adjusted. Ready for immediate use! Nikon NOT included Imagine for a moment that you could one own only two classic cameras, one 35mm camera and one medium format. I imagine the 35mm camera would be a relatively easy choice, since you undoubtedly have one you use more than...

www.petrakla.com

 

[BrianShaw]

Oops, yes, 7cm, not 7.5 cm.

Hi Dan. The 7cm marking on this KA lens vs 7.5cm/75mm markings on later lenses might be an "oddity of marking" and not an actual difference in focal length. I do not know of a change in the Duo design from the earliest ones with the 7 lenses and the ones following with 7.5/75 marking. But that knowledge is only academic as I've never owned one of the earler 7 lenses to actually measure focal length. There certainly are "oddities of data" though as I've seen Kodak documentation that asserts the 75mm lense of the Duo 620 version II as being a triplet...

Finding an element alone seems like it will be a lot more difficult than finding a donor camera, either as a full camera replacement, or as a lens/shutter donor.

 

[svetoklik]

Thank you for your answers.

You can check if it's a triplet or a Tessar type by counting the reflections of the rear group.

Three reflections of the lamp in the group, but more interesting is it true that one lens missing on the top?
Here is two more pictures from links, one is early Tesar type. the other one is original Duo 620 where we can see on the front element with marks one lens right on the ring that is possible to unscrew.
There is not such lens on to my Duo 620.
Well I just have meeting with this Duo 620 after some time in my stash and after touch them have wish to make some photos again.
Great help here will be to figure out diopter of that front lens.
Mean while I will check focus again with more movement and that 10.5 cm Xenar with shooter speed that fires always 125 speed.

 

[BrianShaw]

Is it possible that the front lens cell was disassembled and re-assembled incorrectly... in the wrong order? That could account for the odd appearance of your lens vs the reference lenses as well as explain why it won't focus.

Kodak Compur Duo 620 Series 1 Cameras 1930s. Rare. (ref Nos118)

Kodak Compur Duo 620 Series 1 Camera 1933-1937.Very rare example of the Art Deco Series 1 Camera.There is a film in the camera! Made at the Kodak AG/Nagel-Werk in Stuttgart, Germany.Camera has Kodak Anastigmat F3.5 7cm lens. Camera in good condition, there is ware to the casing, see photos. It...

www.thenostalgiashop.co.uk

I don't think the 10.5cm lens will work in the Kodak Duo due to the configuration of the camera and the focus mount.

 

[OAPOli]

@svetoklik whether it's a Tessar/Xenar type or triplet, there will be two separate elements in the front group. I count four reflections, which means two elements.

Have you tried to disassemble the front lens? Are there one or two lenses? As @BrianShaw suggest it could be that one of the two elements is on backwards. Usually the double concave central one.

 

[svetoklik]

That will be first step to check position of two elements. I see two screws on the top plate from both sides of the name Kodak.
Is someone is familiar with dissembling this lenses?
I have forgot what I did last time. I do not have professional experience, only basic knowledge with few successful repairs earlier.

 

[Dan Daniel]

Unscrew the lens body to get it off the shutter. The two silver screws on the flat top of the shutter are for the shutter top cover, not the lens. The lens simply screws in and out. Well, simply maybe depending on corrosion and such.

Get a whole replacement lens. Off of a Zeiss or Rollei. Pop in both front and back groups and see if focus needs shimming. Brian could be right that 7cm or 7.5cm are just marking conventions not actual focal length. The 1 cm distance in lens board position is because of the focus helical on the back of the shutter.

 

[OAPOli]

From your photos, the front element appears convex which is correct. If the front lens was missing, you'd see the central concave element and the appearance would be completely different.

Unscrew the name ring using a rubber tool. Both elements should be accessible. You might need to unscrew the front cell from the shutter first. Flip the central element, reassemble and recheck the focus.

You should check the rear lens as well. The convex surface should face the film. Make sure it is threaded securely.

 

[Dan Daniel]

Many lenses from this time have a set screw in the side and the whole front collar screws off. Sort of like a mason jar lid, capturing the front element with its rim.

 

[svetoklik]

From your photos, the front element appears convex

It is concave and maybe that part was assmbled opposite?

You should check the rear lens as well. The convex surface should face the film

Yes, it is convex.
I have unscrew the name ring, but not the lens. It is asking for more force.
There is also a four screws from back side, but it looks like that they holding whole lenses with shooter on the plate.