Early I-10, sharp or not?

[zhang xk]

Hi,

This is for Michael, and those who has an early I-10 uncoated lens. I never tried one, but today I used it as a macro lens wide open, and shot an image of a watch movement on a Canon DSLR. This early lens has a s/n of 428, and I compared it with a later uncoated I-10 for construction details.
The watch movement image is a 100% crop without sharpening. So it is a very sharp lens, although the contrast is bit low.

Cheers,

Zhang

 

[ZorkiKat]

Zhang tongzhi

The early 1-10 (FED-50) are very competent lenses. If one does bad, it's most likely due to external factors like a mismatched camera body. These lenses have variable working distances and they must be carefully matched in terms of working distance (back register) with the camera.

Some lenses may be found with cameras which they were not originally issued with or else found alone and then mounted on another camera. Aside from mounting issues, the erratic focus that arises from a non-conforming body makes the lens look bad.

To match the lens -even to a prewar FED- the actual working distance of the lens must be determined. This requires mounting the lens on a substitute focusing device. This would consist of a movable tube to allow the mount distance to be varied, and a ground glass on the other end to observe the focus. With the lens set at infinity, the focusing device is adjusted until a sharp image can be seen on the ground glass.

Then, leaving everyting as is, the lens is removed and the actual flange to groundglass is measured, using a very accurate depth caliper. The derived values then become the basis of how much adjustment (through addition or removal of shims) needs to be done on the camera body.

This goes without saying that a camera body adjusted this way can no longer be correctly used with other lenses. The camera becomes a non-interchangeable camera type.

Or, the lens itself could be adjusted. By noting the difference between its actual working distance and the standard 28.8mm register, the shimming needed can be applied in the lens barrel instead.

Jay

 

[outfitter]

Hi,

This is for Michael, and those who has an early I-10 uncoated lens. I never tried one, but today I used it as a macro lens wide open, and shot an image of a watch movement on a Canon DSLR. This early lens has a s/n of 428, and I compared it with a later uncoated I-10 for construction details.
The watch movement image is a 100% crop without sharpening. So it is a very sharp lens, although the contrast is bit low.

Cheers,

Zhang

The one time I tried theuncoated I-10 it was low contrast and not vey sharp - the problem is that there was no standard register so each lens was fit to a particular body and not interchangeable. Unless you are lucky enough to have the original lens/ body combo, using a DSLR may be the easiest most practical way to try the lens - thanks for showing us what it can do. As to construction details my earliest lenses have fine knurling and low buttons but thereafter they are all mixed up - I even have post-war lenses that are fine and low so I would guess that they had machinery for making it both ways and the lens got whatever they picked out of the parts bin in assembly.

Michael

 

[outfitter]

Jay,

How did they use the hole in the back - was it to match the lens to the body?

Michael

 

[zhang xk]

Hi Comrade Jay,

Thanks for the Fed servival education. It is very difficult to set a correct registration distance for a correct pre-war I-10 lens on a given pre-war Fed-1.:bang: So perhaps these should be used as macro lenses on a DLSR? I am impressed of its sharpness. The somewhat low contrast can be adjusted with PS. In fact, I found many Soviet 50mm normal lens can be as sharp as any modern 50mm lens. I especially like the pan cake I-50. So small and light.


Cheers,

Zhang

 

[zhang xk]

The one time I tried theuncoated I-10 it was low contrast and not vey sharp - the problem is that there was no standard register so each lens was fit to a particular body and not interchangeable. Unless you are lucky enough to have the original lens/ body combo, using a DSLR may be the easiest most practical way to try the lens - thanks for showing us what it can do. As to construction details my earliest lenses have fine knurling and low buttons but thereafter they are all mixed up - I even have post-war lenses that are fine and low so I would guess that they had machinery for making it both ways and the lens got whatever they picked out of the parts bin in assembly.

Michael

It is so much easier to find out a sharp I-10 with a DSLR. I have some later coated I-10 that are very sharp and contrasty. Forget about the Russian resolution figures, they could be as sharp as any top Japanese or German top brand normal lenses even for a cheap I-10.

Cheers,

Zhang

 

[zhang xk]

The other two image were shot with a T-22 3E/3G 1:4.5 F=4CM Smena lens. it is contrasty and sharp!

Zhang

 

[rxmd]

How do you shim a collapsible lens?

 

[outfitter]

Hi Comrade Jay,

I especially like the pan cake I-50. So small and light.




Zhang

I have a collapsible I-50 on an early Zorki -1 and all I can say is that the B&W images are luminous - beautiful quality.

Michael

 

[Spyderman]

How do you shim a collapsible lens?

There is a shim inside the lens barrell just like with other FSU lenses. It's just not as easily accessible as in Jupiters...

 

[SteveM(PA)]

Not really applicable, but I just got the later coated I-10, which I'm in love with. So much so that I just ordered a polarizer for it. I have a few large files in my "Totally Soviet" flickr set.

 

[outfitter]

BTW I just figured out how to test the quality of my pre-war lenses wthout owning a Canon DSLR and adapters: screw them on a Zenit C or Zenit M with 39mm lens mount and use them as a macro. Never thought of that before Zhang's experiments - I'm going to give it a try.

Michael

 

[Dave Wilkinson]

Hi,

This is for Michael, and those who has an early I-10 uncoated lens. I never tried one, but today I used it as a macro lens wide open, and shot an image of a watch movement on a Canon DSLR. This early lens has a s/n of 428, and I compared it with a later uncoated I-10 for construction details.
The watch movement image is a 100% crop without sharpening. So it is a very sharp lens, although the contrast is bit low.

Cheers,

Zhang

A couple of weeks ago, at a village auction sale, I bought a box of goodies (Junk!)-in it was a n old (pre-war,I think) col. Elmar, extensive brassing, but clean, clear glass, - hav'nt got round to trying it yet, but this thread has now fired my imagination!.......shades of Cartier-Bresson?......mmmmm.

 

[ZorkiKat]

Jay,

How did they use the hole in the back - was it to match the lens to the body?

Michael

Michael,

The hole (not usually found in most of the common prewar FED) was used as a peep hole to view the focused image on the focal plane. This allowed the lens + body matching to be checked at the factory, and the hole itself was plugged. I would assume that some form focusing screen was inserted in the film channel and the lens focussed on it. The pressure plates have holes in them too. The pressure plates on all of my prewar FED had holes- though they did not have any on their backs.

Jay

 

[ZorkiKat]

How do you shim a collapsible lens?

Philipp

the collapsible barrel is an external sheath which houses the optical unit. The latter is set inside the barrel, and shims can be fit within to vary the installed position of the optical unit. There are pictures of these parts on this page (last row):

http://jay.fedka.com/index_files/Page325.htm

Jay

 

[ZorkiKat]

Using an enlarger to measure lens's working distance

Using an enlarger to measure lens's working distance

Hi Comrade Jay,

Thanks for the Fed servival education. It is very difficult to set a correct registration distance for a correct pre-war I-10 lens on a given pre-war Fed-1.:bang:
Zhang

你 好 Comrade Zhang

According to Maizenberg, the camera was often adjusted to suit the lens as working on the latter is more difficult. He described a double-helical focusing tube used for measuring the lens's working distance.

I use enlarger parts from an toy Jufeng (-a Chinese connection! ) enlarger. The negative stage and the focussing bellows are used. The I-10 would fit well on its lens mount since it uses an M39 thread, like most enlargers. The parts are used like a little view camera. The film holder is fitted with a focusing screen made from a microscope glass slide with some Scotch 'magic tape' stuck very well on one side. The use of glass is necessary because a rigid surface is needed for measurement with a depth caliper.

The rig is used horizontally. The lens is pulled out to shooting position, locked at infinity and then mounted on the enlarger lens mount. It is then pointed to a very distant object. The bellows are racked until a sharply focused image is seen on the groundglass. A magnifier on the other end of the focus screen helps in observing the focus.

Once sharp focus is seen, the bellows focus knob is locked and the lens is removed. The lens board's relative position when the focus was set has to be carefully maintained. The distance between the lens mount flange and the inner (taped)surface of the ground glass is measured with the depth caliper. The value obtained can then be used for calibrating the camera to be used with the lens whose working distance had just been measured.

The I-10 I have measured this way never gave the same back registers. They varied from 28.4 to 28.6mm - far too short of the standard 28.8mm.

There was one instance when I had to adjust both camera and lens. The camera lens mount was rather thick and the total flange to focal distance, even without shim, was longer than the lens's measured working distance. The lens was given some extra shimming (thin copper wire was used) to 'lift' it a bit.

It's not just the 1-10 which have been found to have variable registers. Even an occasional I-22 or even I-50 (all collapsibles- the "rigids" are more consistent) are found with back registers of slightly less or sometimes even greater than 28.8mm.

Jay

 

[zhang xk]

Hello Comrade Jay,

Many thanks for this detailed explanation. So I understand that most I-10s are not good for later Russian rangefinder cameras that has a 28.8mm registration distance. Am I right? Or a 0.2-0.4mm thinner lens mount should be used. It would be easier if the I-10s registration distance is longer than 28.8mm so adding some shims could solve the problem. I have removed all my pre-war I-10s, and now I don't remember which is for which camera body. They are all messed up.:bang: Some pre-war Fed-1s are very smooth. What a pity. Maybe one day, if I must use one of them, I will try what you do. I do find that many lens mount do not have the same thickness.

Kind Regards

Zhang

 

[zhang xk]

A couple of weeks ago, at a village auction sale, I bought a box of goodies (Junk!)-in it was a n old (pre-war,I think) col. Elmar, extensive brassing, but clean, clear glass, - hav'nt got round to trying it yet, but this thread has now fired my imagination!.......shades of Cartier-Bresson?......mmmmm.

Hi,

Is it an uncoated lens? It might be one of the earliest Leica lenses that could fetch big bucks! Just kidding. I have a book with CB's images. They are all low contrast, unsharp images. So an Elmar or I-10 could provide shades of CB with no doubt.

Cheers,

Zhang

 

[outfitter]

Hi,

Is it an uncoated lens? It might be one of the earliest Leica lenses that could fetch big bucks! Just kidding. I have a book with CB's images. They are all low contrast, unsharp images. So an Elmar or I-10 could provide shades of CB with no doubt.

Cheers,

Zhang

HCB rarely focused, he pre-estimated distance. I suspect it wasn't better lenses that improved the sharpness of his images but the introduction of Tri-X which allowed smaller f-stops and thus greater depth of field. Of course he wasn't too careful about exposures either and that effects contrast etc.

Michael

 

[outfitter]

你 好 Comrade Zhang





Once sharp focus is seen, the bellows focus knob is locked and the lens is removed. The lens board's relative position when the focus was set has to be carefully maintained. The distance between the lens mount flange and the inner (taped)surface of the ground glass is measured with the depth caliper. The value obtained can then be used for calibrating the camera to be used with the lens whose working distance had just been measured.



Jay

How do you cope with the pressure plate? I always foun d it very difficult to measure depth without either not quite touching the plate or touching the plate and depressing it slightly?

Michael