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06-30-2015, 10:59 AM - 1 Like   #1
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Unusual 55mm F2.2 M37 Lens

As most of you long time Pentaxians know, I have built a large collection of (mainly) Pentax lenses, from the earliest Takumar M37 lenses for the Asahiflex series through the latest DA lenses for K-mount bodies. My current lens count for various Pentax mounts is 318.

I recently came across (bought on eBay from a Japanese seller, actually) an M37 lens which seems unique. It is the Takumar 55mm f2.2 lens, which was introduced in 1957 in the M42 mount along with the original Pentax bodies which introduced that mount. It was Asahi Optical Co.'s first use of the double Gauss lens design, and was the fastest normal lens available from AOCo when it was introduced.

I can find no mention in the literature of this lens having ever been made in M37 mount, but I'm holding one in my hand as I write this. It bears serial number 179057. The preset aperture mount looks the same as my M42 copy of this lens except that it has an M37 thread. The mount shows no sign of having been cut down from an M42 mount version, and it has all the original DOF markings intact. I suspect that it could be a prototype made at the very end of the Asahiflex era to evaluate the new lens design before the Pentax bodies were introduced, but of course I have no way of proving this.

I'd like to ask of you who are into Pentax esoterica and history to tell me anything you might know about this lens. To reach a broader audience I'm also posting this message in the DPR Pentax SLR forum. Thanks in advance for any light you can shed on the history of this lens!

Regards, Jim

06-30-2015, 11:05 AM   #2
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Could you post a picture or two? My best guess is that the mount was somehow replaced (perhaps professionally), but I can't say I've heard of the lens in the M37 mount.

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06-30-2015, 11:21 AM   #3
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QuoteOriginally posted by Adam Quote
Could you post a picture or two? My best guess is that the mount was somehow replaced (perhaps professionally), but I can't say I've heard of the lens in the M37 mount.
Adam I think this may be it...
Very RARE EXC Asahi Kogaku Takumar 55mm F 2 2 for Asahiflex M37 Mount G50 | eBay

Scroll down for photos.
06-30-2015, 06:36 PM   #4
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QuoteOriginally posted by UncleVanya Quote
Adam I think this may be it...
Very RARE EXC Asahi Kogaku Takumar 55mm F 2 2 for Asahiflex M37 Mount G50 | eBay

Scroll down for photos.
Yes, that's the lens I bought. I have also posted photos of my own in the DPR forum: Photos...: Pentax SLR Talk Forum: Digital Photography Review. The M37mount really looks original - no signs of being a modified M42 mount. Look at the quality of the engraving of the DOF scale on the mount.

I suppose I overpaid, but rarities like this have their own rules of value to collectors like me. At least it is in very nice condition! Now I have to give it a field test. Luckily I brought my M37 -> K mount adapter with me to our summer place.

07-01-2015, 05:48 AM   #5
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QuoteOriginally posted by jamesk8752 Quote
Luckily I brought my M37 -> K mount adapter with me to our summer place.
Gee, Jim, I didn't even know that there were M37-to-K adapters available. Many moons ago I had to use both an M37-to-M42 adapter and an M42-to-K adapter (both jen-you-wine Pentax versions) to mount a couple Asahiflex lenses on an LX. The only bad part was that the M37-to-M42 adapter had a flange that prevented focusing all the way to infinity. (Of course, I really only wanted to focus back into the 1950's. ) Does your M37-to-K adapter allow for infinity focusing?


07-01-2015, 07:04 AM   #6
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A intriguing lens for sure. Could you post a image of the M37 & M42 side by side for comparison. I am looking at my M42 version on AP body at the moment and the first thing I noticed is the the lens distance scale is marked in meters & feet where my M42 55/2.2 only has feet markings (S/N 146309). The 55/2 on the Pentax K is the earliest M42 lens I have with both feet & meter markings. The rear of the mount looks exactly like the M42 version. However the inner ring on the lens group appears to be a bit thinner on mine than on your M37. Looking at the location of the 2 rear mount mounting screws they appear to be in the same position relative to the edge of thread but they would have to be 2.5mm closer to the center for M37. Looking at the location where these screws fix to the main body on the M42 version there would not be enough room for them to be located 2.5mm closer to the center. Have you checked the diameter of the rear lens group to compare it to the M42 version? I would think the elements would need to be a little smaller in diameter.
07-01-2015, 08:39 AM   #7
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QuoteOriginally posted by Tool_Horder Quote
A intriguing lens for sure. Could you post a image of the M37 & M42 side by side for comparison. I am looking at my M42 version on AP body at the moment and the first thing I noticed is the the lens distance scale is marked in meters & feet where my M42 55/2.2 only has feet markings (S/N 146309). The 55/2 on the Pentax K is the earliest M42 lens I have with both feet & meter markings. The rear of the mount looks exactly like the M42 version. However the inner ring on the lens group appears to be a bit thinner on mine than on your M37. Looking at the location of the 2 rear mount mounting screws they appear to be in the same position relative to the edge of thread but they would have to be 2.5mm closer to the center for M37. Looking at the location where these screws fix to the main body on the M42 version there would not be enough room for them to be located 2.5mm closer to the center. Have you checked the diameter of the rear lens group to compare it to the M42 version? I would think the elements would need to be a little smaller in diameter.
Did you see this picture?
07-01-2015, 02:54 PM   #8
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That is the image I was looking at and it looks exactly the same as my M42 version right down to the location of the rear screws relative to the outer mounting thread and the inner diameter of opening. The only variation appears to be the thickness of the inner lens group ring as mine appears to be much thinner. This gives the initial impression that the lens design is the same between the 2 versions. What I am trying to work out is where they were able to gain the extra 5mm diameter reduction for it to become a M37 and if it is actually the same lens design as the M42. It sure looks like it is, but it can be a little deceiving trying to compare / estimate measurements from a image on a computer screen to an actual object which is I why I mentioned a image side by side so they are at the same scale. Looking at the image and a measurement on computer screen the flange part of mount and the black inner rear section of mount are of equal size. Looking at and measuring my M42 the ratio of the rings is the same (approx equal sizes). So assuming that the overall diameter of lens is smaller to retain the same ratio between the 2 areas it would also mean that the lens group would also have to be smaller.

07-01-2015, 05:35 PM   #9
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I have heard rumors that some of the last run of Asahiflex IIa cameras were available with M42 rather than M37 mounts. I wonder if it's possible that the early original run of M42 lenses could have been also produced briefly, or on special order, in M37 as well as a benefit to the existing base of Asahiflex owners? Or perhaps what you have is a prototype....
07-01-2015, 06:54 PM   #10
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QuoteOriginally posted by fwcetus Quote
Gee, Jim, I didn't even know that there were M37-to-K adapters available. Many moons ago I had to use both an M37-to-M42 adapter and an M42-to-K adapter (both jen-you-wine Pentax versions) to mount a couple Asahiflex lenses on an LX. The only bad part was that the M37-to-M42 adapter had a flange that prevented focusing all the way to infinity. (Of course, I really only wanted to focus back into the 1950's. ) Does your M37-to-K adapter allow for infinity focusing?

@Fred-

My M37 -> K mount adapter looks like it was fabricated from two adapters cemented together, a chrome plated M42 ring surrounding a brass M37 ring. I found that it didn't *quite* focus to infinity (the M37 inner ring was very slightly higher than the surrounding M42 ring) so I carefully filed the inner ring down flush to the outer ring. Now it focuses slightly beyond infinity with my 83/1.9 lens, which has the shallowest DOF of the M37 lenses in my collection. The others seem to have correct infinity focus.

---------- Post added 07-01-15 at 09:11 PM ----------

@Tool_Horder-

My face is red! I thought I had a Takumar 55/2.2 in my collection but looking more carefully I find that I don't - an omission I must remedy in the near future! So I'm sorry, but I can't show the two lenses side by side as you requested.

Thanks for your comments regarding the M42 version of this lens. My M37 version also has both feet and meters on the distance scale.

Odinz' speculations about the possible fabrication of the earliest M42 lenses in both M37 and M42 mounts is interesting and fits with my thinking. Could you share the S/N of your M42 55/2.2? I wonder if it is close to 179057, the number on my lens.
07-01-2015, 09:14 PM   #11
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Don't you hate it when you don't have something you thought you had and when you can't find something you know you have! Maybe a sign of too many toys.

Anyway here's the images of a m42 55/2.2. Looking at the rear mount you can see why it would have been interesting to see them side by side for comparison as they appear identical and there appears to be no room to scale down to M37. I have included a rule in the last image so hopefully you may be able to pick the differences having something to scale it to.
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07-03-2015, 06:28 PM   #12
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Unfortunate development...

Today I tried mounting this lens and found to my surprise (and disappointment) that it was actually an M42 mount, not an M37 mount as the seller had (twice) stated. What an embarrassment! I should have checked it immediately after receiving it, but didn't. I've advised the seller and expect that he will either accept a return with full refund or accept a much lower price if I keep it.

My apologies to all of you who responded with your thoughts about it. I should have been more suspicious given the front bezel designation and the size of the optical unit in the rear view.

Sometimes a thing is too good to be true...
07-03-2015, 07:13 PM   #13
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It looks very much like an older (smaller form factor) silver CZJ Tessar 50mm f2.8....definetely a triplet design..

07-03-2015, 10:04 PM   #14
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QuoteOriginally posted by jamesk8752 Quote
Today I tried mounting this lens and found to my surprise (and disappointment) that it was actually an M42 mount, not an M37 mount as the seller had (twice) stated. What an embarrassment! I should have checked it immediately after receiving it, but didn't. I've advised the seller and expect that he will either accept a return with full refund or accept a much lower price if I keep it.

My apologies to all of you who responded with your thoughts about it. I should have been more suspicious given the front bezel designation and the size of the optical unit in the rear view.

Sometimes a thing is too good to be true...
After several exchanges of emails, the Japanese seller has agreed that he made a mistake and has refunded my payment, so at least all I will be "out of pocket" is the return shipping. Too bad; I would have loved to have owned such a unique lens. The perils of being a collector... ;<((
07-04-2015, 05:05 AM   #15
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QuoteOriginally posted by jamesk8752 Quote
My apologies to all of you who responded with your thoughts about it.
No apologies needed, Jim. I at least (and I think I'm not the only one) enjoyed the investigation and the conjecturing --I (we?) enjoyed the adventure.

QuoteOriginally posted by jamesk8752 Quote
Sometimes a thing is too good to be true...
Sometimes 'tis.true. However, I'll bet your eyes will still open just a little bit wider whenever you see an "odd" M37 lens up for sale in the future...
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