Mamiya 80mm TLR lens type

[RidingWaves]

Hey optical fans, trying to figure out the optical type of the Mamiya 80mm TLR lens. Looks kinda like a modified Tessar to me, but not quite. It goes (] [))( [)() single element, cemented pair, stop, cemented pair. The rear pair looks very much like the rear pair on a Tessar, but the cemented pair and then the single element doesn't fall into a Tessar, in fact I can find no other similar lens. Any help/discussion would be appreciated.

[AdrianW]

The 80mm f/2.8 is a 5 elements in 3 groups design that is very similar to the Heliar. The only difference I have seen is that the Heliar usually has the single element in the middle rather than in front like the Mamiya.

There is a rare 80mm f/3.7 lens that Mamiya also made for the TLR. This is a 4 elements in 3 groups design that is very similar to the Tessar. The sharpness of this lens is excellent.

[RidingWaves]

Yeah, the 105DS is a straight up Heilar, but the front cemented pair puzzle me, the curve grouping looks like an 'extended' Tessar in the front.

[David Brown]

There is a rare 80mm f/3.7 lens that Mamiya also made for the TLR. This is a 4 elements in 3 groups design that is very similar to the Tessar. The sharpness of this lens is excellent.

I have that lens. It was my understanding that it was a standard lens with the C220. (I bought mine used almost 40 years ago.) Never knew it was "rare". :p

[AdrianW]

David, the f/3.7 was supposedly a budget lens that was only available with the purchase of the C220. I don't know if it was even offered as an option if you bought the C330. Because it got the "budget" title I think the general thought is that it must not be as sharp as the f/2.8. However in my tests the sharpness of the f/3.7 actually slightly surpassed that of the three f/2.8 lenses I compared it to... and that's quite impressive for a low cost lens!

[grahamp]

The Copal shutter on the 80mm f3.7 is supposed to have a quirk - the release will move even if the shutter is uncocked. I wouldn't mind confirming that for my documentation. If you have a Seiko/Seikosha shutter version, I'd really like to hear about it.

This is one lens that will not autocock on the C33/C330 bodies because the shutter cocking arm throw is wrong.

http://www.gapatterson.com/grahamp/mfaq/m_faq.html

[AdrianW]

Hello Graham, I have a black f/3.7 (taking lens ser. #19080). It has the Copal shutter and you are correct that the shutter release on mine will move even when the shutter is uncocked.

BTW, the research information you have on the Mamiya TLR system is amazing. I have referred to it many times when I've had questions on this system - thank you for making it available!

[Q.G.]

The Copal shutter on the 80mm f3.7 is supposed to have a quirk - the release will move even if the shutter is uncocked.

What does "move" mean in this instance?

[AdrianW]

What does "move" mean in this instance?

The shutter release on the f/3.7 lens will go down when you press on it even if the Copal shutter is not cocked. On all the other Mamiya TLR lenses that I've tried - the ones with the Seiko shutters - the shutter release locks up until the shutter is cocked. This prevents accidental double exposures.

[Q.G.]

I see. Thanks for explaining.

[grahamp]

Normally this is not a problem if the body double exposure interlock is set. But in Multi mode, or if you want to manually trip the shutter for multiple exposures, there is no tactile feedback on the state of the shutter. Just a quirk.

[Q.G.]

Hey optical fans, trying to figure out the optical type of the Mamiya 80mm TLR lens. [...] Any help/discussion would be appreciated.

Where can we see the cross section of this lens?

[Michel Hardy-Vallée]

Mamiya has put on their website PDF scans of the original documentation. If you look for the depth-of-field tables file, you will see the following cross-sections:

80mm:
http://www.apug.org/forums/attachment.php?attachmentid=17465&stc=1&d=1269109955

105mm DS
http://www.apug.org/forums/attachment.php?attachmentid=17466&stc=1&d=1269109955

[Q.G.]

Thanks!

That 105 mm is the achetypical Heliar, as was mentioned before.

I can't place the 80 mm. Looks a bit like a simplified Hektor.
Definitely looks like it is a true "triplet", in that you can flip groups, push them together and obtain a solid piece of glass with flat ends.

[Michel Hardy-Vallée]

Somehow, the 80mm looks like an alternate-reality Heliar. The latter is a Tesar with an extra lens on the first group, whereas the 80mm follows the same approach, but on the middle group.

One thing we're sure is that it's not a symmetrical lens, and that it's not a speed lens. Rather looks like the kind of lens that, like the Tessar, performs very well stopped down. But I'm just extrapolating, since I own the 105m DS and not the 80mm.

[Q.G.]

If the front lens had been an achromatic doublet, it would be exactly like a Hektor.

If the front lens had been an achromatic doublet, and if the middle group had been a single element, it would be exactly like a Heliar.

So i'd say it's closer to the Hektor.

[Michel Hardy-Vallée]

http://www.winlens.de/fileadmin/user_upload/Bilder/Lens_types/bild-26.gif

Very close to the Hektor, but a single front element, not a doublet.

[RidingWaves]

Hey, great input everyone, I was certain someone would give insight. I did consider it along the lines of the Heilar. Regardless, I've never seen another 'standard' lens for MF that has this or close to this formula. The Mamiya TLR system has some unique lens formulas.