Odd (Early?) "Micro Tamron" 70mm f5.6; Any Info?

MacTak · Joined: 15 Jun 2011 Posts: 108

First let me say I'm a long time follower of the forums here (as a MF lover, particularly Pentax glass). I saw this lens on Ebay and as a MF lens lover, particulry macro lenses, I could not pass it up. But searching the internet I was not able to find any information on this lens (or anything except the auction listing).

Aperture is directly controlled by the front ring. Middle ring is focus, last is just for grip. Aperture does have proper detents and half-stops. Focusing scale (metal, held on by screws) is in inches and cm goes from to 260cm/90in. Focuses down to 40cm/16in. Build is excellent--feels on par with my Takumars. Lens is coated. It seems like a muti-coating as well, but I'm not an expert on judging that.

Even Tamron's old lens page (http://www.tamron.co.jp/data/old-lens/old-index.htm) does not list it. I rather suspect it is a medium format lens. With the Taisei Kogaku in the name, it's clearly an early Tamron lens. The lens is just under 2.5 inches long. Front filter is 52mm diamter, rear screw mount looks to be about 55mm in diameter. I have no idea what the mount of this lens is. The rear mount part itself is attached with screws, almost as though it was removable or easily factory made in different mounts. Note that there indeed screws partailaly visible under the rear baffle/opening.

Aperature design is rather wierd--I've never seen any quite like it. 8 primary blades plus 8 secondary blades Here you can see it from the front. First wide open. Then stopped down.

Now from the rear it gets even stranger. First, the rear side looks more like you'd expect the aperature to look from the front of a normal lens. Secondly, upon stopping down (particulry at the higher aperatures) a second set of 8 blades starts to emerge! As you can see, the are right underneath (thinking of the front of the lens as the top) the normal blades, not really visible when looking from above. But look carfully and you can see how the the pins (which hold the aperature blades) have moved in towards the center of the lens, and so these secondary blades actually fill in the gap that would otherwise be left as the top part of the aperature moves inwards.

Wide open:

Fully stopped down:

So, can anyone shed any light on this lens and the mount (not to mention how best I might adapt it to Pentax K or M42 or even M39).

cooltouch · Joined: 15 Jan 2009 Posts: 9096 Location: Houston, Texas

Looks like you've found a real puzzler there, MacTak. Seems to me that any lens labeled "Micro" would focus closer than 16"/40cm. And that aperture iris seems like really excessive overkill. Very strange.

You can find out about its coverage, or image circle by just holding up to a wall in a room where there's a window opposite the wall. Let the sunlit image coming in from the opposite window fall on the wall. Focus the lens. This will tell you two things -- the size of the circle will tell you what sort of format coverage it can provide, and the distance from the rear element -- or rear lens flange to the wall will tell you the lens's registration distance.

It looks to be in very clean condition, especially since it dates from -- what do you figure? 1960s?

martyn_bannister · Joined: 23 May 2010 Posts: 1151

Certainly I can't find a reference to this lens in the Vade Mecum. 70mm doesn't seem to be a popular prime lens length. Judging by the unusual mount, would this be an enlarger or even a projector lens?

ManualFocus-G · Expire: 2014-11-24

Incredible first post, I've never even heard of this one before! Great find!

martyn_bannister · Joined: 23 May 2010 Posts: 1151

What I find unnerving is that the focus scale goes from 90 - 16 inches - but no mention of infinity Shocked

Surely this must be a projector or repro lens? A lens for an enlarger usually uses movement of the enlarger itself to focus and a camera lens would surely have an infinity focus mark? If it were a macro lens designed for bellows use then the focus scale is redundant and/or the numbers are meaningless?

Totally weird! Would be great to find out what the register distance is and how it performs Smile

PS - it might be worth mailing tamron themselves with a link to this thread to see if they can shed any light on it. Might be one for their museum Smile

M. Valdemar · Joined: 14 Nov 2008 Posts: 93

I think that lens was probably part of a macro bellows system. Spiratone sold similar set-ups.

kds315* · Expire: 2021-03-09

I would agree on that, most likely for a repro bellows system.

Interesting lens, would fit my macro-lens collection Wink

aoleg · Joined: 22 Feb 2008 Posts: 1387 Location: Berlin, DE

I've seen a similar arrangement with two sets of aperture blades on some Russian lenses, notably Helios-40. I, too, think it's excessive overengineering; it seems the designers used this arrangement to provide for linear movement of aperture control ring (that is, to keep ring travel the same between, say, f/2-2.8 and f/11-16).

MacTak · Joined: 15 Jun 2011 Posts: 108

Thanks for all of your replies so far. Yes, it's quite the puzzling lens, so I had to finally join up to share. The focusing distance was (and still is) the biggest puzzle for me. It seems odd for a such a distance either for macro work (per the lens name) or in general (no infinity). My first thought when I saw a photo of the lens (before I read that it had a focusing helicoid) was that it was an enlarger lens. The focal length and speed, micro name, and manual aperture ring at the front all most closely resemble an enlarging lens. But then it has the helicoid.... It's very strange for a normal lens to just have a manual (non preset) aperture ring at the front. A reproduction bellows lens makes some sense, but I still fail to see the point of designing the lens with a helicoid then. Also, why does it have such a sizable 55mm mount then? I see no great reason to make a bellows system with such a mount instead of M42/M39/T2, etc., and certainly this lens could have such a mount size. And let's not forget Tamron (which seems quite exacting about listing every lens they ever made) does not list the lens at all--pity I don't know Japanese or I'd write them. Anyone who does is welcome to (or give me a heads up if you know a contact in english).

I'll see if I can try the format test as soon as I can--unfortunately my apartment doesn't get the best direct sunlight, but I'll see what I can do. I will add that while I can't say much about the optical design, it looks to me that there are at least two elements in front of the aperture and at least two behind.

Originally I was thinking of adapting it, but short of gluing on a flanged K-mount adaptor, I don't think there is any good way to do it, and since the lens is indeed so rare, I think that would be a crime to lens-kind to do so. Pity I don't have a reversing ring right now. I try *not* to be a pure collector, so much as a user who accumulates enough lenses to probably be called a collector, so I wouldn't be opposed to seeing this happily in a collection or the Tamron museum Wink

martyn_bannister · Joined: 23 May 2010 Posts: 1151

luisalegria · Expire: 2018-01-18

Joining all the rest in appreciation of this unique find !
Thanks for showing it to us !

Tamron hasn't fully documented all the lenses they made, not by a long shot. There are plenty of ordinary SLR lenses they have not included on their site, nor have they been listed on the Adaptall-2 site. I have several.

Among other things they have not listed the specialized lenses they made for many commercial purposes. One of them is a monster zoom they made for Camerz medium-format portrait cameras.

This looks like another lens made for a specialized camera, obviously one designed for close focus. I suspect it wasn't a repro camera, but who knows. The 55mm thread seems like something made for a unique mount.

It may be possible to easily mount this on an SLR, depending on the back focus. One way would be to use a 55mm-55mm F-F adapter plus a reverse adapter for the desired mount.

MacTak · Joined: 15 Jun 2011 Posts: 108

cooltouch · Joined: 15 Jan 2009 Posts: 9096 Location: Houston, Texas

luisalegria · Expire: 2018-01-18

54mm is Series VII (old non-metric filter thread system). Best to make sure with calipers.

There are Series VII adapters, like for instance 49mm-Series VII step-up rings. I have a couple.

The thread pitch may not be the same as Series VIII, but if its 54mm at any rate it should thread at least partially on an adapter ring.

So a 49mm-Series VII step up, a 49F-49F adapter, and a reverse adapter - NOT to mount the lens reversed, but because its got a camera mount on one end and a 49m on the other. With this rig you will have the lens in a "normal" orientation.

The critical point is what sort of back focus you've got. You may have to add a spacer ring in there too, maybe, to get infinity, or if unlucky the thing will be even more "macro" than its marked.

martyn_bannister · Joined: 23 May 2010 Posts: 1151

kds315* · Expire: 2021-03-09

How about a calipher and a visit to a mechanic? Or is that to much engineers thought... Wink

cooltouch · Joined: 15 Jan 2009 Posts: 9096 Location: Houston, Texas

MacTak · Joined: 15 Jun 2011 Posts: 108

Okay, I've sent off an email to support @ tamron. If that does not work I'll try sales and see where they direct me. As to the exact mesurment of the mount, alas, I don't have any capliers, nor can I trek to a mechanic at the moment for an offical measurement. Mayhaps I'll just take my chances with a Series VII ring--that would make sense as a possible mount. It's only $3 for a ring, so I won't be fuming if that turns up bust. I am aware of the chance that this may indeed be some odball thread for which nothing works. By the way, the Tamron 90mm macro I have is the 172E (the later AF f2.8 1:1 macro).

Anyway, I did try a few pictures today holding the lens on my bellows + K-5 (about 35mm of extension thus added--not sure if this lens can make infinity even sans bellows). Alas, the sun did not cooperate and I was forced to use slower shutter speeds and higher ISO's than I wanted (and shoot only wide open), so none of these are probably as sharp as they can be. Still, I was quite pleased with the way the lens performed. Coverage, as expected, is no problem. The lens seems quite sharp wide open, with good colors and pleasant bokeh. Spherical aberation in at this range appears slightly undercorrected, hence the smoother background blurring; longitudanal CA was extremely little (and I saw no lateral CA although I'm not sure I would have found it today anyway); contrast was average. Here are a few shots of the dustiest objects I could find (sorry no masterpieces today):

It handeded the dreaded metal spatual quite well too:

martyn_bannister · Joined: 23 May 2010 Posts: 1151

That looks pretty darn decent Smile

MacTak · Joined: 15 Jun 2011 Posts: 108

Finally had some sunny weather to try a little more with the lens. I was able to find some lateral CA in the corners of the money pic, but otherwise I was very impressed with the performance of the lens. Razor sharp. Very nice rendering, contrast, etc. I'd say it performs like a top notch enlarging lens. Here are a few at f8 (f5.6 seems almost, if not just, as sharp):

This one is wide open at f5.6:

Here's one showing the aperature blade shape at f8:

It handles metal very well:

100% crop of the above:
http://s592.photobucket.com/albums/tt4/quasar41/Camera/?action=view&current=IMP08393-1.jpg

A 100% crop from a shot of a washcloth:
http://s592.photobucket.com/albums/tt4/quasar41/Camera/?action=view&current=IMP08333.jpg

cooltouch · Joined: 15 Jan 2009 Posts: 9096 Location: Houston, Texas

If it's very sharp on the corners of flat subjects, it may have been a purpose built repro lens. And one where color was important, too, I'd say.

martyn_bannister · Joined: 23 May 2010 Posts: 1151

yes, an excellent render. Tamron will be proud when they read your e-mail Smile

simple.joy · Joined: 30 May 2022 Posts: 587

It's 'Why-not? Wednesday' again, so time to dig up a really old thread, right?

D1N0 · Joined: 07 Aug 2012 Posts: 2530

Looks like that if you take out the aperture flange you'd have a 70/2.8 lens of there about.

simple.joy · Joined: 30 May 2022 Posts: 587

Found one of those lenses and while it's not labeled it's indeed suspiciously similar to the Taisei Kogaku Micro Tamron. Looks very much like Tamron to me and the serial number would fit in as well, making it a later build than the one mentioned in the OP.

Bad weather here today, but here's a shot: