Image offered per request from Michael Piziak-- to see an image taken with the old 50mm SMC Pentax f:4 Macro. (Serial # 5074188.)

Here is an image I shot with the 50mm macro--I had commented in his thread that my version of the lens was less than crystal sharp when focused on infinity.
This image has not been processed in any way--just converted from DNG to JPG.
The exposure is a half-stop under exposed (per K-1 ii light meter).
Lighting was light overcast--no defined shadows, but not dark overcast.
Lens set on infinity--distance to objects approx 75 meters +.

In this image, both the resolution as well as the contrast appears to be slightly less than I get with the SMC-A 100mm f:2.8 macro when shot at infinity. (Of course, considering the magnification is 1/2.)
I believe that the old 50mm f:4 is expected to be very sharp when used in macro mode, but falls off when used as a standard lens. That seems to bear out in the case of my own lens, as seen in this image.

Any comments from other folks regarding this lens / image are also welcome.
Angky.

[Argos]

Macro lenses in general are not constructed for infinity focusing, but for short(er) distances. Some macro lenses do however produce decent results at infinity and long(er) focusing distances.

[ToddK]

I don't think that I have taken many shots at infinity with any of my macros except the DA35mm Limited, which does a fine job as a landscape lens. I will have to try my FA50 macro and see how it does.

[angkymac]

Macro lenses in general are not constructed for infinity focusing, but for short(er) distances. Some macro lenses do however produce decent results at infinity and long(er) focusing distances.

Thank you! That goes right along with what I had heard from another photographer.
Good to have it confirmed.
Angky.

---------- Post added 10-03-21 at 08:17 PM ----------

I don't think that I have taken many shots at infinity with any of my macros except the DA35mm Limited, which does a fine job as a landscape lens. I will have to try my FA50 macro and see how it does.

If you find the 50 to be a bit weak at distance shots, that would be good to know.
My 100mm f:2.8 macro does pretty fine at any distance, but I think it was specially set up for that--even focuses slightly beyond the typical "infinity".
Your 35 must be quite a lens; seems I recall a shot you posted where it really did a spectacular job on a very close-up macro.
Angky.

[Argos]

I don't think that I have taken many shots at infinity with any of my macros except the DA35mm Limited, which does a fine job as a landscape lens. I will have to try my FA50 macro and see how it does.

The DA 35 Ltd is a very nice lens, but on the K-1 at infinity or long focusing distances, it does not cover the entire picture frame. At short(er) distances, it does, however.

[angkymac]

The DA 35 Ltd is a very nice lens, but on the K-1 at infinity or long focusing distances, it does not cover the entire picture frame. At short(er) distances, it does, however.

Thanks much for that important info!
I might suspect then, that the very fringe edges of the image will probably have fall-off issues while the main part of the image will be pristine.
Thanks for your post.
Angky.