Leica LTM Summitar Diaphram Blades

Leica M39 screw mount bodies/lenses
doubs43

doubs43

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I've had a Summitar (1951) 5cm lens for many years and it has the somewhat odd diaphram blades that look like a dog's leg. Today I received a 1950 Summitar and the iris diaphram blades are the normal type.

If you have a Summitar 5cm lens, what do your blades look like?

Walker
 
700xxx and 790xxx both have nice round holes.

Yours looks like a Summar diaphragm sort of. Summar were discontinued in the late 1930. . 700xxx is coated so it is 1946 or later.

What is the serial no.?
 
So, based on this very little info, it looks like Leitz switched the style of aperture blades in the later Summitar lenses, using dog-legged blades which result in a hexagonal aperture.

I wonder why the switch?
 
Serial 589xxx, 1942, coated, ten flat blades with round hole. Domestic production (meter scale, no "Germany" marking).

I think I've read that this serial number block was factory coated.
 
Serial No. 702xxx, manufactured in 1949, has ten normal blades with round hole. Scale in feet, marked "Germany".
 
My 1950 Summitar with 10 circular blades is #763282. I just got it today and the coating is absolutely perfect..... no cleaning marks whatsoever.

My 1951 Summitar with the dog-leg blades is #932805. I've owned it since 1971.

Thanks to everyone for the input. It would seem that Leitz used both type of blades and it's possible that the later Summitars were made with left-over dog-leg blades just to use them up. Manufacturers don't waste materials if they can use them.

It would be interesting to know which were used when over the years.

Walker
 
FrankS said:
Walker, so you're suggesting maybe Leitz was using up left over Summar aperture blades?
Click to expand...

Frank, I think it's a possibility but, of course, wouldn't claim it as fact. Everyone with Summitars who have kindly volunteered their information from the early 1942 example into 1950 production has the ten flat blades. The one late 1950 owned by John and my 1951 example have the Summar-style dog-leg blades. If Leitz knew production of the Summitar was ending and had a supply of Summar blades in stock that would work, it makes perfect sense to use them. I seriously doubt that they'd want to use them on the new Summicrons.

Sometimes supply problems create a situation that forces a manufacturer to use older parts.

The Summitar was made until at least 1953 when it was replaced by the Summicron. It would be interesting to hear from others having Summitars from 1952 and 1953. A total of 170,000 Summitars (approximately) were made.

Your example in the 724xxx range is a 1949 production lens.

Walker
 
I have 2 Summitars. The one made in 1949 has a round iris opening and the normal blades and the one made in 1951 has a hexegonal iris opening and the dog legged blades. I had read somewhere that Leica made this change in late production Summitars. You seemed to have found the change over peroid as some time in 1950.

Nikon Bob
 
As I speculated on photo.net on the same subject, perhaps the spherical blade profile corresponds with when they changed the smallest aperture from f:12.5 to f:16?
 
John (Shriver) I've noticed that the later style blades do move the aperture forwards as they are stopped down. Very interesting idea.
 
Summicrons have the normal flat blades. John S suggested that physically moving the aperture forward while stopping down may improve optical performance. The dog-legged blades seem to do this. (Move the aperture forward.)
 
John Shriver said:
As I speculated on photo.net on the same subject, perhaps the spherical blade profile corresponds with when they changed the smallest aperture from f:12.5 to f:16?
Click to expand...

Both my Summitars go to F16 and one has the normal blades and the other the dog legged style.

Nikon Bob
 
Summar manufacture ends in 1940. To discover old stock of aperture blades after 10 years and a war seems unlikely. I've not has a Summitar apart so wouldn't know if Summar blades would fit.
 
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