More on kodak duo 620 lens

[javier_gonzalez]

My recently bought Kodak duo 620 II is equipped with a kodak anastigmat 75 mm,

f3.5, compur rapid, scale in meters, and the engravings in german. Looking for

information on this camera there seems to be a consensus about the K.A. being a

rebadged Xenar (see this thread:

http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=00FVVo).

I have read a document in a place named orphancamera a document where it is

clearly stated that the K.A. in the duo 620 II is a triplet. Cleaning the camera

I also noticed that the rear element is rather thin, an only two reflections are

present, so it really think this is a single element rather than a cemented

pair. By the way, the lens is pretty sharp (see tha attachments). What do you

think about it?<div></div>

[javier_gonzalez]

A blow up of the lettering in the previous image, with no sharpening. Scanned with an epson 2400<div></div>

[Andrew in Austin]

On an Agfa Record 6x9 folder, I prefer the 105mm Apotar, which is a triplet, rather than the 4 element Tessar-type 105mm Solinar. Both lenses only open up to f/4.5 and I usually shoot at f/5.6 to f/11.

 

Your Kodak duo 620 II looks to be performing extremely well. In my neighborhood that house would receive a full restoration.

[winfried_buechsenschuetz1]

The third reflection on the rear lens group usually is very faint since it comes from a cemented surface. The difference in refraction index between the two lens elements is much lower than the difference between the lens elements outer surface and air (the r.i. of the latter being 1). Also, due to the curvature of the cemented surface this reflection usually is very small compared to the reflections of the outer surfaces.

 

Anyhow, there are some triplet designs out there which perform surprisingly well, the old Meyer Trioplan is one of them. But in most cases you can see the difference to a Tessar design when checking the distortion of image elements close to the edge.

[sw12dz]

Nice shot. Do not lose too much sleep over the details of lens construction. If you are happy with the results and enjoy using the camera, then just go out and have fun!

[gene m]

Love it.

[profhlynnjones]

Hi Javier,

 

The original description says KA or Z Tessar (1933-1937). The Ser. II (1937-39)description doesn't change but the Ser II W/RF (1939-40) states Kodak Anastigmat. Kodak never put an outsider lens with a Kodak name on it so I'll guarantee that it isn't a repackaged Xenar. Remembaer that several Kodak cameras made in Germany had German lenses but they were so marked (Xenon, Tessar, etc).However, whoever said that the KA was a triplet was wrong. The KA was always a 4 element tessar type lens of darned good quality.

 

By the way, the name "Ektar" was a qulity standard, NOT a lens pattern.

 

Lynn

[javier_gonzalez]

Thanks for your answers. Please, don't missunderstand me: I have no complaints at all about this camera or its lens construction. I think it is really a GREAT camera and the lens is a jewell. In fact, after looking for a pocketable medium format classic, and trying a nettar and a bessa 66 with heliar, I prefer the kodak (the camera itself and the kind of images it produce), so I will keep it.

It is just I like to know the history of the classics I own (for me is part of the fun of using these cameras) and I was surprised that many people was sure that the KA was a Xenar.

Winfried: you are right, the third reflection is very faint, but in every cemented pair I have looked at (industar, xenar, belar and kodak anastar), is present, but not in this one. Morover, the cemented pairs have usually a flat or concave surface, and this one has two convex surfaces (of course, this is not definitive). Finally, I think it is very thin to be a pair (of course, I may be wrong).

 

Lynn: are you sure that all kodak anastigmats were 4 elements?. In the document cited above there are lots of 3 element anastigmats. I have owned two 6x9 kodak folders equipped with f4.5 anastigmats that were triplets for sure.

 

If some of you own a similar camera, could you confirm these guessings?. Thank you again.

[peter_naylor1]

Javier has definately come up with some sort of Rosetta Stone with that page 41 of the 1946(?) Kodak Lens Guide. It not only describes the KA f3.5 lens as a triplet, it also has an optical diagram - one could be an error, but surely not both!

 

It was me who kicked off the original thread last year about the Duo-620 and its regional lens variants, and I got a lot of helpful data which enabled me to give my presentation to our Cam Coll Club here in Perth, plus write a couple of articles for Mischa Konig's Kodak website based on it. Basically I was convinced that the KA f3.5 and f4.5 were just rebadged Schneider Xenars, seeing as they looked identical and had similar chronological numbering. However, despite finding several road tests, adverts and other stuff about the Duo-620 during that research, not one of those items specifically mentioned the optical design of the KA lens. That Page 41 is the one and only Kodak-sourced item I've seen which gets into that sort of detail.

 

I'm still firmly convinced that Schneider of Kreuznach made these KA lenses due to the serial numbering being so consistent, but now I'm beginning to think that perhaps the USA-market KA lensed Duo-620s might have been fitted with rebadged Schneider Radionars, which was Schneider's best triplet of course. It still doesn't make sense to me just why Eastman Kodak of Rochester would have opted for a lesser triplet lens when the European market models got a kosher 4-element Tessar design on such an otherwise advanced model. However, George Eastman died a far richer man than I will, so I'll bow to his company's decisions no matters how illogical they appear in 20/20 hindsight. You also have to consider that this was not a cheap camera. It sold for the same price as the Retina 1 in the USA.

 

I'm going to get our local Repair Guru to have a close look in his Zeiss Collimator through several of my Duo-620s' optics to confirm that the KA ones are indeed triplets. Then if that's confirmed, I guess I'll have to eat humble pie and rewrite that article for Mischa's Kodak website.

[davecollopy]

"By the way, the name "Ektar" was a qulity standard, NOT a lens pattern."

 

Before the Ektar line was introduce the Kodak Anastigmat held that honor. It was never a single lens pattern, although most if not all were a four element design. Many four element Anastigmats were certainly not a tessar design. The Anastigmat Special was however a tessar, as well as some of the No. 32 KA line. After the Ektar line was introduced most if not all Kodak Anastigmats were a three element design. Truth is, there is no way to be sure what lens design a kodak anastigmat might be without inspecting it.

[wigwam jones]

"George Eastman died a far richer man than I will"

 

But not a very happy one, sadly.

[javier_gonzalez]

Thank your Peter for your kind response. If it is a triplet, it is indeed a very good one, or at least the better I have used. I have found it sharper than the heliar and the novar anastigmat I have also tried. The few copies I have made of the negatives from this camera, have also a distinctive character hard to describe. I suppose it is "classical look". I sincerely doubt the xenar would perform better than this lens in real world situations. So, unless the lens in my camera is exceptionally good, I think it is a very good choice for a high end camera like this.

Thank you also Stuart an Gene for the cumpliments. Best regards

[davecollopy]

I will second the f/2.9 Meyer Gorlitz Trioplan as being a most exceptional lens. I once had a Balda-Six with the 7.5cm Trioplan that was sadly lost in a fire. I've had much difficulty locating another. Rodenstock also made several high quality three element lenses. In the forties Kodak began producing a three element lens, the Anaston, which I felt was also a notable lens.

 

The thing about the three element lens is their range in quality. There are some very good ones, and there are some real dogs. Before lens coating was common a four element three air space lens produced an unacceptable amount of flare limiting its usage. A three element two air space lens manged flare in an acceptable manner. The tessar was originally considered a modified three eleement design. Its two air space design handled flare while its four elements made it a consistent performer that still makes it a popular design with camera manufacturers to this day.