Optical differences between Takumar and K-mount lenses?

[bsbxl]

Can somebody clear this up for me? The K-mount series of Pentax lenses and the Takumar lenses seem tot resemble each other very much (eg. K28/3.5, K35/3.5, K55/1.8, K105/2.8 have similiar Takumar counterparts). Are the K-mount lenses in fact Takumar lenses with a different mount and esthetics or are there other (optical) differences? Thanks.

Bsbxl

[Ole]

I'd speculate that many of the K lenses optically are the same as their SMC-Takumar counterparts. I don't see why Pentax would have had any desire to redevelop all those lenses - it would have had no marketing value. The big news at the time was the K-mount, not the lenses.

With the M-lenses the optics were tweaked in some cases. Here the big news - the marketing value - was lighter and compacter lenses for the M-series cameras.

[8540tomg]

I was curious about this myself so I did a little research. Ole appears to be correct in his assumption regarding the conversion from screw to K mount. Danilo Checchi in his book Ashai Pentax and Pentax SLR 35mm Cameras 1952-1989 states:

“The optical quality of the SMC Takumar lenses was renowned
throughout they world and they ranked among the best of the Japanese
lenses. The bayonet mount Ashai Pentax cameras had been hastily
introduced onto the market and it had not been possible to equip
them with a series of fully redesigned bayonet lenses. The optical units
of the SMC Takumar lenses were assembled on bayonet mounts and
reintroduced onto the market under a different name." (p181)

So optically most, if not all of the K series lenses, are Takumar lenses optically with a bayonet mount and cosmetic differences. Cecchi notes "the following were derived directly from the equivlalent Super Takumars. They had identical optical constructions, but in some cases with a smaller minimum aperture and standard filter diameter." They include:

15mm f/3.5
17mm f/4
24mm f/3.5
35mm f/2
35mm f/3.5
50mm f/1.4
50mm f/1.8
50mm f/2
105mm f/2.8
120mm f/2.8
135mm f/2.5
135mm f/3.5
150mm f/4
200mm f/4
400mm f/5.6
500mm f/4.5
1000mm f/8
50mm f/4 macro

Other K series lenses not listed above were evidently new designs. This includes the K 85mm f/1.8 etc. I didn't feel like typing the list out. See Checchi pp. 182-183 for details.


The Ks are all metal and solid but not as solid in terms of build as the Takumars which are in a class by themselves in terms of build quality.

Tom G

[Ole]

Tom, thanks for the research!

Ole