Originally posted by monochrome Dude. 2000 pieces were made for the Japanese market only. They were specifically marketed by Pentax, through the Dealer chain, to users of rangefinder cameras other than Leica (Minolta, Konica, (Cosina) Voigtlander, Zeiss Ikon, Rollei, etc) intentionally to reduce / avoid conflicts between dealers and their Leica Dealer Agreements. Leica bayonet was still under Patent.
Whether any Leica body owner bought the lens for use on a Leica camera was naturally not the fault of Pentax or the Dealer. So I have gathered anyway, to answer my own questions.
FWIW, I researched the design parameters. The 'Special' barrel is 20mm longer than the regular K-mount 43 Limited to compensate for the Leica register difference. I corrected my earlier post to reflect my misstatement.
Whatever, though. You're better informed than I on the subject.
There were only internet rumors that the optical design were the same, but there were no confirmation nor official announcement about it. It's like Minolta M-Rokkor 40mm really is a Leica Summicron-C or not. Leica people would tell you it's not, but Minolta people would say it's the same optical design but only differ in coating and glass material.
In reality, even you can see lens barrel were different because one is working as AF screw under K mount, the other is a dumb down SM mount. That part is understandable. You can argue that both are from same registry distance so they are somewhat identical optical formula. Grant that...... The reality is both are actually in different filter thread size, different size of front element.. It really isn't the same lens.
One argued that Pentax 43mm Limited is probably best 40mm and I concur the fact it is true to me. Simply because at 70s~90s, Pentax simply was the best lens coating company PERIOD. The SMC not only shared root to Carl Zeiss *T, it also has better performance over most of modern Leica lenses. As for the lens coating, and latest 40mm in the game (besides the Canon 40mm EF-S STM), 43mm Limited was latest innovation of 40mm category. It has best balance between color, sharpness and micro-contrasts.
In my own collection which I have still today. I have Contax G 45mm, Canon 40mm, Nikon 45mm, Leica (Minolta 40mm), Voigtlander 40mm.. and various of 35mm ~ 50mm including Leica. I would say best 40mm is truly the 43mm Limited. However, is Limited vs Special version are two different things? I can not know for sure. If it's the same lens but only different mount, Pentax SHOULD NOT charge them differently. Special version is often double in price, and if it's the same lens, people long ago should already adapt K to Leica M and used it on the Leica body already. But did that happen? NOPE! It didn't.
According to various of Leica fan forums.. they were practically saying, 43 Special is "DIFFERENT" than 43 limited. Although no one really provides actual photos to compare with proof.
The historical fact is that original lens designer on his interview he mentioned he was a Leica Lover but works for Pentax. He was originally designed 43mm Limited as a "LEICA" rangefinder lens but works as K mount Pentax SLR film bodies. That's the reason why 43mm alone has the color characteristics and fidelity looks similar to Leica / Zeiss (somewhat in between).
He tried to keep everything compact and designed both 43 and 77. Till 31mm, his original design was compact wide angle, but wasn't able to boost aperture to a F2.0, so he stepped down and got a career change to different company, then someone else came up with 31mm limited instead. That's why 31mm limited isn't really that compact at all, but it has larger aperture. However, color characteristics no longer like 43mm limited.