Konica 300mm/9 Hexanon GRII

[David Vickery]

Hello,
I recently purchased one of these lenses in a barrel and have put it into a Copal #3 shutter(direct fit). It seems that somewhere I saw a posting about the spacers that are between the lens groups when in the barrel, and that they should be taken out if mounted in a shutter for general photos rather than copy work. Does anyone know if this is correct??

 

[Donald Miller]

I have always heard that the element spacing distance must be maintained when mounting a barrel mount lens into a shutter.

 

[David Vickery]

You are certainly right if the lens in a barrel was originally meant to be used in general view camera work. But this lens started life as a process lens, with much closer work habits, and it had three spacers in it. Does the rule still apply for process lenses being required to work at further distances than they are used to?

 

[Robert]

I'm sure you could improve things with adjusting the lens. The question is how much and do you risk more damage then you gain? I've got a small collection of process lenses. Well it feels like a collection. They all seem to work just fine at infinity. My rule is try it first. You might find it just fine.

 

[Donald Miller]

I have heard that most lenses that were designed for process work will work perfectly well at infinity if they are stopped down sufficiently. I am not an optical engineer but this is what I have heard over the years.

 

[lee]

David,

I have a set of the same lenses ie: 150 210 and 300 that I took off a vertical process camera last year some time. I seem to remember that the camera was a DS America process camera. Try it out without the spacers and let us know the results. I have a 210 g-claron and a 305 g-claron and they don't have spacers in them. They are in a Copal #1. They( the g-clarons) are as sharp as any lens I have owned.\

lee/c

 

[David Vickery]

Hey ya'll, thanks for your input. I too have a number of process lenses that I use on a regular basis. This was the first time that I actually took one out of the barrel and put it into a shutter. The lens that was in the shutter has problems passing light properly. so I thought that I would try the Konica in that shutter. When I took it apart it kinda caught me off gaurd with the spacers.

 

[Ed Sukach]

The lens that was in the shutter has problems passing light properly. so I thought that I would try the Konica in that shutter. When I took it apart it kinda caught me off gaurd with the spacers.

I'm trying to envision this. When you speak of "spacers between groups" are you refering to the internal locations of the single elements or cemented "pairs/ triples" of lens elements - commonly called "groups"?; or are you referring to a removable "section", used to change focal length - as in "convertable" lenses?

First, the caveat: "I dunno ... anything is possible." Without some indication of the construction of the lens, I'd have to make that answer.
Second, having spent some amount of time working in optical qaulity control and observing problems from spacer errors - defective (out-of-tolerance sizes; wrong ones installed ...) I would say that there would be very little chance of improving the performance of any lens by modifying group placement. If it does, I would be the firt instance I've every heard about.

Give it a shot. Let me know what the results are.

 

[Robert]

Didn't the shutter mounted Artars come spaced differently ?

 

[David Vickery]

Okay, I see your points about groups and such. I am only talking about removing the front half of the lens from the barrel and the rear half from the barrel(not taking those apart any furthur). I put these into the Copal #3 shutter (direct fit) with out spacers and the image looks good on the ground glass, but I have not made any exposures yet. Probably for contact printing I will never notice any difference regardless of whether I use the spacers or not. But I may at some point want to use this lens for 4x5 color, so I was thinking that if this lens can be optomized for infinity work then I should try to do that.??.

 

[David Vickery]

Yes Robert, that is what i am talking about. It does seem that the artars had different spacing if they came from the factory installed into a shutter. but I have not personally seen it.,??.

 

[Donald Miller]

It would seem that the only way to determine the effect of different group spacing would be to use an optical bench. I do know that Steve Grimes (RIP) determined by micrometer measurement the spacing of the groups as they were in the barrel and he insured that this same spacing was maintained when he mounted the front and rear elements in the shutter. I assume, therefore, that there must be a good reason. Among those might be coma, spherical aberations etc. Those would not necessarily be readily apparent by viewing the "sharpness" on a ground glass.I have found, in my experience, that lens performance is readily apparent even on a contact print. Obviously the effects would be more noticeable as the degree of enlargement increases.

 

[tim atherton]

The Kowa process lenses (which in some versions, as Computars also came mounted in shutters) come with little brass spacers and the following info:

"Some times the barrel lens will come with thin spacers. The trick

is this, for center image use, the more spacers between the rear cell and

the shutter the better. For the corners of the image, no spacer is best.

This is why, in a shutter mount, we often see one spacer as the best overall

compromise."

tim