Help Identifying Goerz Lens

aconbere · Aug 12, 2023

Hi all, first time poster,

I found this lens at a rummage sale this weekend and I’m hoping someone here might help me identify it.

It is a Goerz lens labeled only “C.P. GOERZ AM OPT CO” with the serial number “No K795892”.

It has a minimum aperture of f6.8 and a maximum of 45. I haven’t had much luck guessing the focal length.

abruzzi · Aug 12, 2023

ƒ6.8 is what most Dagors have, so that would be my guess. I'd unscrew the front elements or stop all the way down and see what kinds of reflections you get to see if you can guess the design.

aconbere · Aug 12, 2023

I’ve removed the front cell for cleaning, when looking through it I’d guess that I’m trying to see how many elements it’s made out of. Any hints as to what that would look like?

abruzzi · Aug 12, 2023

glass/glass transitions make a dim reflection. glass/air make a bright reflection. The Dagor has three cemented elements on each side, so you have AG--GG--GG--GA, which should be strong-weak-weak-strong I believe.

EDIT: also, guessing the focal length is best done on a view camera, focused on something close to infinity. Based on the size of the lens and the size of my Dagors (assuming it is a Dagor) I'd guess it is probably a 210mm or 240mm or so.

aconbere · Aug 13, 2023

Not sure if order matters but in this picture you can see two small weak reflections and two bright ones.

aconbere · Aug 13, 2023

As for focal length, I dont have a view camera on hand (but i’m going to pick up a crown graphic tomorrow, maybe I’ll be able to adapt it). Thanks for the help!

David Lindquist · Aug 13, 2023

Kenro was a brand of copy camera/compact process camera. Goerz supplied them with lenses; the serial number would be preceded by the letter "K". Guessing that since Goerz and Kenro needed to know the focal length but the end user of the copy camera didn't, that information wasn't engraved on the lens.

Robertson was another maker of this sort of equipment. The lenses Goerz supplied them had a serial number starting with "R".

Often when these turn up on ebay they are described as being a Dagor, probably because they are made by Goerz and they, well, look like a Dagor.

David

aconbere · Aug 13, 2023

Makes sense! So it sounds like I’ve got a Goerz lens made for Kenro that is likely a Dagor design and I should try mounting it to my crown graphic and see what focal length it is.

Seems like it should be a pretty nice lens.

aconbere · Aug 13, 2023

Oh! Last question - Does anyone know what size shutter a lens like this might fit into? I’d love to explore mounting it into shutter for use with the crown graphic.

abruzzi · Aug 13, 2023

its unlikely it will be a direct fit to a shutter. If you have a graphic with a FP shutter that is the easiest (I think those were called "speed graphics" but I know little about the Graphic lineup.) Alternatively you can get someone to make a front mount adapter to fit it in front of a larger shutter. SK Grimes if the most common machinist for that kind of surgery, but you are likely starting to get into the expensive category.

Alternativley--use a slow film and a small aperture, and use the hat shutter. Or find a cheap packard shutter and rig something up for that.

aconbere · Aug 13, 2023

Ah bummer, the graphic I have doesn’t have a focal plane shutter. I was hoping it might fit into a standard like #3 shutter and I could easily drop it into a lens board. I think the lens cap method would also be fine but might require a little more effort on my part to fit the lens to the board.

Dan Fromm · Aug 13, 2023

aconbere said:
Ah bummer, the graphic I have doesn’t have a focal plane shutter. I was hoping it might fit into a standard like #3 shutter and I could easily drop it into a lens board. I think the lens cap method would also be fine but might require a little more effort on my part to fit the lens to the board.

Depending on the lens' size, using an adapter to hang it in front of a shutter might be possible. SKGrimes has made such adapters for me. I suspect, can't be sure without knowing the lens' size, that mounting it on the front of an Ilex #3 might be possible.

Also, since one never knows, unscrew the cells from the barrel and measure their threaded sections' diameters. They might fit an Ilex.

See skgrimes.com for shutters' threading.

By the way, a 4x5 Crown's maximum extension is 12.5"/317.5 mm. The lens may be too long to focus on one. Check this -- hold the lens in front of a board -- before doing anything more.

AnselMortensen · Aug 13, 2023

I have made "quick & dirty" temporary lens boards out of 2-ply mat board for testing focal length, vignetting, etc.

aconbere · Aug 14, 2023

Well i have a ton of mat board so maybe that’s something to explore today.

aconbere · Aug 14, 2023

Precision mat board construction! Looks like a good bet at 8 1/4 but we’re bumping up against the limits of my measurement.

aconbere · Aug 14, 2023

@Dan Fromm I went to measure the threads today and realized that… maybe I don’t actually know how. Here’s what i could figure out.

Just looking at the front element:

inner diameter: 40.1mm
outer diameter: 41.4mm
depth: 3.75mm

I have a thread gauge but I’m honestly confused on how to use it.

Zathras · Aug 15, 2023

aconbere said:
Precision mat board construction! Looks like a good bet at 8 1/4 but we’re bumping up against the limits of my measurement.

I think you're right about it being 8 1/4. I have a very similar looking lens that has GOERZ AM OPT CO around the front of the lens and it also
includes the words DAGOR and FOCUS 8 1/4 IN. Mine is mounted on a ancient 3 1/4 x 4 1/4 RB Auto Graflex.

aconbere · Aug 15, 2023

@Zathras wow! I hadn’t ever gone to actually look at the graflex SLRs and THAT is a wild camera :-D

Dan Fromm · Aug 15, 2023

aconbere said:
@Dan Fromm I went to measure the threads today and realized that… maybe I don’t actually know how. Here’s what i could figure out.

Just looking at the front element:

inner diameter: 40.1mm
outer diameter: 41.4mm
depth: 3.75mm

I have a thread gauge but I’m honestly confused on how to use it.

Thanks. A little too large to stuff into the front of a #1 (40 mm ID, tube length 20 mm), but could be attached using a cup-shaped adapter.

Front mounting on an Ilex #3 (ID 45.3 mm, tube length 21 mm) would be better, should reduce the risk of vignetting considerably. I believe that a threaded bushing, which will allow the rear of the lens to go deep into the front of the shutter, is possible, could be mistaken. Ask a machine shop.

MTGseattle · Mar 23, 2024

I'm jumping into this thread as I just took a gamble on ye olde auction site. The picture was blurry and there was only one. I shot a pretty lowball offer out.
The lens is labeled Goerz Optical Co inc. L.D. Artar 24" F11 As near as I can tell, serial number is 6 digits and I think 82556? I've stumbled around and found that the Low Dispersion/Distortion was already a feature of these lenses but it being marked as such is somewhat uncommon. What I'm really curious about is if it's an Aluminum barreled 24" or not as that would be pretty neat.
I'll find out in a week or so. It's mounted on some big metal plate and shipping in a wooden box, so the tax and shipping combined to make it not a steal, but still a decent deal especially if it turns out to be the alloy version. Fingers crossed.

JPD · Mar 25, 2024

MTGseattle said:
The lens is labeled Goerz Optical Co inc. L.D. Artar 24" F11 As near as I can tell, serial number is 6 digits and I think 82556? I've stumbled around and found that the Low Dispersion/Distortion was already a feature of these lenses but it being marked as such is somewhat uncommon.

It's actually typical of Goerz. Many of their lenses were symmetrical, or near symmetrical, and were marketed for their low distortion. For a process lens like the Artar this was even more important, and it came on the market in the early 1910s! The rare LD version is supposedly a later tweaked design and even better.

Ian Grant · Mar 25, 2024

abruzzi said:
ƒ6.8 is what most Dagors have, so that would be my guess. I'd unscrew the front elements or stop all the way down and see what kinds of reflections you get to see if you can guess the design.

So are the Goerz Syntors, the reflections look typical for a dialyte.

Ian

MTGseattle · Mar 27, 2024

I received the lens. It’s an anomaly I think. It seems way too heavy to be an Aluminum sample. The mount flange is brass for sure. Serial numbers match front to back.
It arrived mounted to that crazy Aluminum plate and in a wooden box.
Thankfully, the glass is in great shape. The aperture has just a slight hesitation, but is smooth past that, and the blades look good to my eye.
My question for anyone sitting on Goerz info is how do these measurements jive with published ones?
Mount thread diameter on barrel = 3.027 inches
Diameter of mounting flange threads = 2.972 inches
Thread pitch for both is 24.
There’s no way this is going into a Copal 3
My measurements were done with a Mitutoyo digital caliper, and the pocket knife style imperial thread pitch gauge.

Ian Grant · Mar 28, 2024

L.D. means Low Distortion. The Goerz catalogues I've seen don't list dimensions just coverage and that's huge.

We don't see Goerz Am Opt lenses here in the UK, but I use similar lenses with front mounting ThorntonPickard roller blind shutters (very rare in the US), or a large Gitzo front mounting studio (leaf) shutter, with flash sync.

Ian

MTGseattle · Mar 28, 2024

I'm suspicious that this L.D. 24" is bigger than its more common Red Dot 24" brother. That's what I am trying to nail down. I know that the threads that mount the front cell group and rear cell group into the barrel will be a bit smaller than the barrel and flange threads, but not by a lot I don't think. I've seen examples now of Red Dot Artar 24" F11 mounted into 3 different shutters.

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