[crabe919]

Hello,

Would there be a significant difference between these two lenses optically?
Which one would you choose for best performance?
The A setting doesn't matter, shooting 99% of the time on film.

Regards,

Adam

[Adam]

There's probably not much of a difference optically: certainly not something you'd notice on film. Unless you plan on going digital in the near future, you might as well get the K version if it'll save you some money.

[baro-nite]

One difference that will be more important on film than on digital is the color rendering. My copy of the K version is decidedly warmer than more recent versions. Another small consideration is filter thread size -- the K has a 52mm thread but all later versions have 49mm.

Although the optical formula is largely the same for all versions of this lens, there are apparently some minor changes that came in with the A version; anecdotal reports suggest it is sharper at some apertures than earlier versions.

[Edit:] How timely; see also https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/241226-smc-...yellowing.html

[crabe919]

thanks for the reply's

would the warmer color/yellowing affect b&w film also?

[monochrome]

would the warmer color/yellowing affect b&w film also?

IMHO there isn't enough difference between K and A to be noticeable on film unless the exact same images were viewed side by side. However, the fact that commenters wrote about the difference suggests they were aware of it enough to make allowances for it in expectations..

Anecdotal references on the internet from the late 90's through the late-2000's (when active interest in mf Pentax lenses began to leave the mainstream) suggested two changes when the A version was released:

1. Slight tweaks to the optical formula to improve corner sharpness
2. Continuation of the improvement to the SMC coatings and application process which it is suggested made the output noticeably cooler than the K.
3. Use of more plastic than the M version, and a distinct "feel" of the focusing helicoid and aperture ring compared to the M and K.
   1. I don't recall a consensus preference for the feel of either lens - but passionate opinion on either side.

Personally, I kept my K50/1.4 and sold all the M and A 50's, mostly for sentimental reasons, but also for the build quality and feel. I've also kept a small group of Takumars for the same reasons.

[crabe919]

monochrome,

thanks for your input, if output is cooler think i will hunt down a K version then.

Regards,

Adam