Summitar aperture blades?

[rtphotos]

Just curious. When (either year or serial #) did Leica switch from the aperture blades from circular to hexagonal shape on the Summitar lens?

I've heard that the earlier circular style creates better bokeh. If anyone can post them, I'd love to see side-by-side comparisons.

thanks,
rt :)

[OldNick]

Can't answer the whole question, but can give you a data point. My Summitar, SN 702xxx from 1949 has the round aperture configuration.

Jim N.

[planetjoe]

Here's (http://flickr.com/photos/redframephoto/392707652/) another data point, my old round-iris Summitar, sn 668338. This (http://www.forloren.dk/lbf/leica_lens_serial.htm) website puts the date of manufacture somewhere in 1948.

I sold that one and kept a "hex-iris" model, because I actually liked the OOF-effect it produced. You might see the general effect in the attached photo, which was shot pretty much wide-open.

I seem to recall a discussion (which I now can't find) concerning the difference between these two versions of the Summitar. My understanding is that the earliest Summitars were the ones that had a minimum aperture of f/12.5, not 16; in this way it isn't the iris type that determines the age, but rather the f-stop scale. As for the hex-iris models, I have seen at least a few comments that suggest they were the product of left-over iris assemblies from the Summar production line, and so they show up in only a semi-chronological fashion. Hopefully someone more knowledgeable than myself can shed some light on this.

Either way you slice it, these were great lenses, and remain some of my favorites.

http://www.rangefinderforum.com/photopost/data/500/200609090205_thedresser_4x6x100.jpg


Cheers,
--joe.

[1948nikon]

My Summitar 763577 has round blades. I am not sure of the year.

[Nikon Bob]

No real answer here either, just a couple of data points. The one Summitar that I have is serial #7250XX with round iris, 2-16 and was made in 1949 according to a web sit. The second one has serial #9389XX with hexagon iris, 2-16 and was made in 1951 according to the same site. I would guess at around 1950 the change was made if these lenses were on either side of the change.

Bob

[John Shriver]

My Summitar is 589XXX, putting it in 1942, round aperture, coated.

I don't think they could re-use the Summar curved blades in a Summar lens, the adjacent lens element is larger in diameter, and less steeply curved.

If they changed to the curved blades late in production, the reason was probably to improve performance at small apertures. Perhaps the change to an f/16 minimum aperture revealed this some issues at small apertures?

[rtphotos]

Thanks all for the info and data points. :)

So far, aside from any possible anomalies that Leica threw into the pot, the switch between round to hex irises appears to have taken place somewhere between 763577 (1950) and 9389XX (1951).

Keep posting your data points!

"planetjoe", good photos are good photos regardless of the len's aperture blade type and bokeh. Thanks for posting your wonderful photograph.

Thank you for keeping this temporarily home-bound photog occupied. ;)

rt

[Telewatt]

My Summitar is 589XXX, putting it in 1942, round aperture, coated.

I don't think they could re-use the Summar curved blades in a Summar lens, the adjacent lens element is larger in diameter, and less steeply curved.

If they changed to the curved blades late in production, the reason was probably to improve performance at small apertures. Perhaps the change to an f/16 minimum aperture revealed this some issues at small apertures?

From November 1945 the coated lenses were produced, so your lens was coated later..

some lenses in wartime had a special coating only for Millitar..

regards,
Jan

(the Summar had the special curved blades for the Agfa Color Filter)

[tripod]

My LTM coated f16 Summitar is #724xxx from 1949 and has aperture blades that form a round opening.

[Luddite Frank]

It seems that changing from a circular to a hexagonal diaphragm opening is a bit of a step backwards ?

( Or am I missing something ? )

Luddite Frank

[Matthew Allen]

My 1951 Summitar #931xxx has the hexagonal aperture. I seem to remember reading another thread on the subject that suggested it depended on batches rather than Leitz having definitively switched from round to hexagonal on a particular date. I've no idea why this would be, perhaps someone with more knowledge of Leica history could offer an explanation.

Matthew

[tripod]

The question remains: why switch from a nice round aperture opening to a hexagonal?

[Telewatt]

The change to the hexagonal was 1951....why ? I do not know..but I think money is a idea..;)

[Gabriel M.A.]

The question remains: why switch from a nice round aperture opening to a hexagonal?
Somebody must've had a "who cares!" moment after coming back from vacation?

I don't get why they didn't stick to the circular aperture. My newer Summitar had a hex iris, my older one has a circular one. Both my Summar and Xenar (precursor to the real Summarit) have the "hex" iris.

[tripod]

Did you notice a difference, Gabriel?

[Charles Woodhouse]

So far we have a latest round iris Summitar No.763577 and I'll add a friend's hexagonal iris that I serviced three years ago, No.813393.
All my Summitars from 487599 to 761603 have round irises and I'm still looking for a hex iris as a user/collector.
487599 has a coated front element and sits on a IIIB.

[Gabriel M.A.]

Did you notice a difference, Gabriel?
Stopped down, yes. The diaphragm dial on the round iris lenses seems to feel smoother than the hexagonal iris, too. They (hex) also seem to close in a non-flat way. Weird.

Ultimately, I think the rounder the iris, the better. But as they acronymize, ymmv ;)

[John Shriver]

According to Puts' book (citing two disagreeing sources), my lens was factory coated. Coating started in October 1941. Not all production was coated, just for "war photographers". Also, it may be a later lens than 1942, Puts' sources note that the serial number block allocated in 1942 for Summitars was still being used in 1945.

As for why the hexagonal iris, the other difference is that the hexagonal iris is not flat. It is curved, domed, and rides very close to the rather deeply curved rear element of the front group. So as the iris opening closes up, it moves toward the front of the lens. This is why I think it was done for optical reasons at small apertures.

It's definitely more expensive to make than the 12 bladed round iris. There are still twelve blades, but in two different shapes. They all have a complex curve. Half of them form the aperture, the others provide stiffness, and cover gaps between the other blades. All the blades are quite narrow.

I only have the hexagonal domed blades in my Summar. I've had them apart, and put them together again. Not something I want to have to do again, a very fiddly project.

[Todd.Hanz]

Hex here, Sr. 7978** LTM. I won't speculate as to why...but this lens has a distinct flavor.

http://www.rangefinderforum.com/photopost/data/500/ty_n_amanda_summitar.jpg

http://www.rangefinderforum.com/photopost/data/500/fri_after_5_100_dpi.jpg

Todd

[planetjoe]

Here's another data point (took awhile to get around to it): my "keeper" Summitar, f/16 with hex iris, is 903127, which puts its manufacture sometime during 1951. This corroborates, more or less, the data we've been seeing.

Thanks for your comments, rtphotos. I'm glad you've started this thread - the Summitar is really a great little lens. Okay, not so little; after moving on to a collapsible Summicron as my "daily driver", I was personally struck by its heft but rather smallish size. The Summitar, by comparison, seems a larger lens - a real light-collector.

As for the hex iris itself, I'm in conceptual agreement with John Shriver, who pointed out the probable optimization of the Summitar's "new" small aperture. The iris assembly dome moves forward as it closes, reaching a minimum aperture almost directly behind the front element. Forgot I had noticed this.

You guys are going to get me to take the Summitar out again. Good show.


Cheers,
--joe.

[rtphotos]

Ok, I think with everyone's help we've narrowed it down even further. I searched the archives for the earlier post Joe mentioned reading and came across this 2 year-old thread:
http://www.rangefinderforum.com/forums/showthread.php?t=19518

In that thread "ffttklackdedeng" states that he has a round iris summitar with serial 792XXX, the latest recorded round-type I've come across to date.

And Todd Hanz has just noted that he has a 7978XX which makes it the earliest recorded hex iris summitar so far. [By the way Todd, fantastic images, and definitely distinctive].

So somewhere between 792XXX and 7978XX (ca.1950) is the turning point between round and hex irises from what I've seen.


You guys are going to get me to take the Summitar out again.

Great! Everyone, shoot'em up! :) And thanks, J. Shriver for your input and interesting info.

rt

[Telewatt]

According to Puts' book (citing two disagreeing sources), my lens was factory coated. Coating started in October 1941. Not all production was coated, just for "war photographers". Also, it may be a later lens than 1942, Puts' sources note that the serial number block allocated in 1942 for Summitars was still being used in 1945.



...I only have the hexagonal domed blades in my Summar. ....

The coating of 1941 was a different coating, because of the Zeiss rights ...an yes, only for military...the normal Zeiss/Schott coating was from November 1945...


the hexagonal blades in the Summar was for the Agfacolor film with the special Filter, so you needed the form...

regards,

Jan

[Drambuie]

I have just recieved a Summitar 8564xxx with hex (curved) blades. Discussing this with our beloved Malcolm Taylor he suggested the change was an attempt to improve on some abberations inherrent in back-end of the Summitar design. As the discussion moved quickly on to other 'Malcolm' topics I didn't find out any more ... next time maybe. A