135mm Upgrade from f3.5 to f2.5.

Just got my hands on a MINT, New, Unused, 1:2.5/135 Asahi Pentax Super Takumar.

I have been shooting with a 1:3.5 Super Takumar and have been absolutely stunned with the results.

I'll have to do a roll of comparison shots of course, but thought I'd ask the experts here, what to look for.

Besides the size, (58mm filter vs 49) and weight (Very hefty), I noticed right away that the lenses are constructed very differently and now wonder if there is a fundamental difference in how they perform.

Thank's in advance.

Oh, and John - I also got the 50mm Macro - also pure mint, but missed out on the f2.3 35MM Auto Takumar. Was at work at auction's end and the snipers went wild at the last minute - went for $128.00 US. Not meant to be.

Cheers

Can't win them all, Mac....

As regards the 135mm lenses, I have used a bayonet version of the f2.5 but there have been a few design changes, so comparisons may not be valid. I would expect it to be an excellent lens, but hefty compared to the f3.5 version.

Personally, I much prefer the 100mm/105mm lenses, finding the 135mm a little too long.

Hi Mac,
I must admit I like the 2.5's. The construction is basically the same as the early SMC ones. There was a slightly different later one which is what the K series lens was based on. Overall, it is a very good performer and the extra speed makes a big difference in focussing. Not only the extra brightness but also the shallower depth of field helps.

Regards
Kim

Thank's Gentlemen.

Can't wait to try it out!

John, I know what you mean about 135's being a little too long - especially in the field. I like to use them as "across the room" informal portrait lenses.

Cheers

Just a bit more info. The optical design of the Super Takumar and Super-Multi-Coated takumar 135mm f2.5 lenses is the same (5 elements/4 groups) but there is also an improved Super-Multi-Coated Takumar (Model II) (6 elements/6 groups) only differentaited by its slightly longer length ( 85mm instead of 80mm) and slightly increased weight (470g as opposed to 455g).

I took this info from the "Asahi Pentax Screw Mount guide" by Oosten, which I would thoroughly recommend to anyone interested in screw mount cameras and lenses.

Hi John,
This is what I was referring to in my earlier post. The K series lens was based on the 6/6 design. There was a similiar design evolution in the 85's when the design changed from a 4/5 F1.9 to the 6/6 F1.8. A quick source of reference is the AOHC site here http://www.aohc.it/lense.htm .

Regards
Kim

Also, the bayonet Takumar version was simplified to 4 elements in 4 groups, and even this lens is very acceptable, although not up to the critical standards of the others.