I am looking for some help in choosing a used Summicron-M 35mm f2 lens. I have a chance to choose between a older M lens ser #278xxxx and a newer one 3xxxxxx lens, they both are Canadian made, but i notice a difference. When the lenses are wide open at f2, the leaves of the older one are completely open whereas the newer one seems to have a bit of the leaves remain(still can see a bit of the octagon shape thru the lens. Is this normal the way this lens was design ? or ...... Your valuable input are much appreciated

thanks... Stan

-- Stanley Chao (carschao@magma.ca), December 08, 2001

Answers

You may find that the aperture ring on the newer one can be turned so that the aperture blades are fully open. It's as though you are getting an f1.8 or f1.9 lens instead of an f2. This is not uncommon and I have a 35/2 Asph that does this. I don't think it makes the slightest difference one way or the other. Personally I would try both lenses out, if possible, and pick the best one.

-- sam smith (Ruy_Lopez@hotmail.com), December 08, 2001.

The low production nature of the Leica lenses shows itself here! When I first got my 90mm f2.8 Elmarit, I was concerned that at f2.8, the aperture blades were not fully open. I actually called a Leica service center and found out that Leica calibrates each lens to the maximum f stop listed, and mine was probably actually something like f2.7, so it stops down a tiny bit to get to a fully accurate 2.8 as indicated on the click stop. While were on the subject, do you see the tiny number next to the large M on the focus ring? That tells you exactly what focal length your lens is-- my 50mm Summicron is actually a 52.2mm lens,(the number 22) and my 90 Elmarit is a 91mm lens(the number 10). Does any of this mean anything in real world shooting? hell no, but I get a kick out of the precision that goes into this stuff.

-- Andrew Schank (aschank@flash.net), December 08, 2001.

has anyone ever seen a 50.0 or a 90.0 summicron?

-- stefan randlkofer (geesbert@yahoo.com), December 09, 2001.

My 35mm Summicron ASPH hasn't got the little numbers at all. Does that mean it's exactly 35.0 mm?

-- Nigel Bowley (nigel.bowley@btinternet.com), December 09, 2001.

They use different mounts with matched focal lengths just for the 50mm and longer lenses. My vote goes for the 3 xxx xxx lens.

-- John Collier (jbcollier@powersurfr.com), December 09, 2001.

Stan,

Thanks for the great timing as I was going to ask the question about my Summicron 35mm f2 lens SN # 3505XXX which also has the blades slightly showing at f2 ....... I have had it for a year or so and no problems that I can see from this condition ......

Craig Egerer

-- Craig Egerer (camwatch@chartermi.net), December 09, 2001.

My 35mm Summicron (pre-aspheric) also has a very slight bit of closing of the blades when the aperture is set to f/2. I was concerned, but when I was able to talk to a Leica technician at a local shop that was doing a clinic for Leica users, he told me it was normal and showed me another sample with the same configuration.

Additionally, to corroborate, in the "Leica M, Advanced school of photography" book on page 63, there is a lesson on aperture induced artificial vignetting, which uses this same lens to demonstrate why at full aperture there is light fall-off, and you can clearly see the not quite round edges of the aperture blades at f/2.0.

As a test, I shot slides at f/2.0, f/2.8 and f/4.0 while adjusting the shutter speed to compensate, and all slides have the same density. I just quit worrying and have been using this lens for over a decade now.

-- Al Smith (smith58@msn.com), December 09, 2001.

The diameter of front and rear components of pre-asph Summicron is slightly enlarged to reduce a fall off. The main aperture diameter of its predecessor coincides with the diameter of aperture set at f2.0.

-- Victor Randin (ved@enran.com.ua), December 10, 2001.

The diameter of front and rear components of the pre-asph Summicron is slightly enlarged to reduce a fall off. So we can see edges of aperture leafs at f2.0. The opening of its predecessor coincides with the diameter of the aperture set at f2.0.

-- Victor Randin (ved@enran.com.ua), December 10, 2001.

Andrew,

Amazing news. My 75 lux is a 00, my 50 cron a 19, my 135 Elmarit a 50 - does this mean it's a 140? 35 cron and 21 Elmarit have no no.s...?!

-- Lutz Konermann (lutz@konermann.net), December 10, 2001.

First of all, please accept my sincere thanks to all of you who contributed the answers, as they are very informative and precisive. Guess what I went ahead to buy the newer model with the 3xxxxxx one, i will provide you with the result later ......

Until then, have a good holidays.... Thanks... Stan

-- Stanley Chao (carschao@magma.ca), December 10, 2001.