35mm Summicron f2 weirdness?

[drazin]

i have a version 4 35mm summicron f2 which seems to have an EXTRA wider stop then f2 its hard to explain, but i can set the aperture at f2 as seen in the left side of the attached photo and then i can set it to something wider then f2 which is not marked on the aperture dial as seen on the right side of the image. when i do this and look at the aperture blades, it does indeed look to get wider when its past f2. what does this mean!?

sorry for the bad pics, (it was my cellphone camera) and i can take better pics tonight if anyone needs clearer images to make out the problem here.

 

[Guy Mancuso]

It may not mean much if the exposure from it is identical. Sometimes there is play in the aperture ring. My Schnieder 47mm apo digitar does the same thing

 

[robsteve]

On some of the Leica lenses, the aperture is slighly closed even at the wide open setting. I think it may be a design decision, to get optimum quality.

Robert

 

[Stuart Richardson]

Most Leica lenses do this. I believe that last bit of play on either end of the ring is designed to compensate for differences between actual lens speeds -- Leica lenses tend to be made on the basis of what is good, rather than exact specs -- this is why there are occasionally two tiny numbers on the edge of the lenses -- it is the exact focal length. Mostly the slightly older lenses have this. For example, my 90mm Tele-Elmarit has "00" marked near the infinity mark. This means it is 90.0mm, a true 90mm lens. My 75 lux has "50" which means 75.0mm, a true 75mm. On the other hand, my 50mm summilux ASPH says "14" which means it is a 51.4mm lens, not a 50 or even a 52.5, which is the actual "true" 50mm lens target focal length.
So it is my hypothesis that this extra movement on either side is so that they can adjust the iris to a true, exact f/2 and f/22 (or f/16, f/32 etc). The funny thing is Leica does a lot of stuff like this -- truly precision construction, but they don't tell anyone about it! Most other companies would market this sort of thing, but Leica is not that savvy.

 

[Mark Gowin]

This thread got me curious so I checked my lenses and found the 28 Cron ASPH, 35 Cron ASPH, and 90 Cron ASPH all have the extra little bit of aperture past the f2 mark. The 28 Elmarit ASPH, 50 Lux ASPH, and 75mm Summarit do not have any extra play past the max aperture. (I didn't check the WATE)

Also, my 50 Lux ASPH has a "14" marking and my 90 Cron ASPH has a "10" marking as described by Stuart. None of the other lenses have extra markings.

Mark

 

[matmcdermott]

Huh, whaddya know. I always wondered what that very very small 50 was on my 35 Summicron IV. Which, by the way, also turns slightly past 2.0, but won't stick there.

 

[robsteve]

If they were Canon, Nikon or other brand lenses, they would be f1.8 lenses, but terrible at f1.8

 

[ecliffordsmith]

Hi All,

My 35 summicron ASPH does this and the light meter indicates a slight increase in shutter speed when switching to the setting from F2. I just checked again now and at F2 the meter read 90 and beyond F2 125. I do not know how far the meter was from indicating 125 at F2 though of course. I think Rob is probably correct at saying F1.8 or so.

 

[Bob]

I had a similar problem on this lens, but it turned out to be detent alignment.
-bob

 

[Chris C]

I'm very disappointed in the outcome of this thread. I was hoping we had solid evidence [in homage to Sir Nigel Tufnel] that Leica made the occasional lens which goes all the way up to 1.1.

............. Chris

 

[Guy Mancuso]

Sorry Chris there are no freebies from Leica. LOL