[leekil]

The 43 is an AF lens, the focus ring is not well damped for manual focussing. Apart from that, there's not likely to be much difference at f/8 or f/11 with most of the other 50s. It may depend more on the cameras you're planning to use it on.

You can do much worse than the FA43, though, for manual focusing. It moves easily, but does have some damping; it is by no means the loose, completely undamped movement of the FA zooms.

[zapp]

Get a new 50 macro, enjoy warranty and AF.
f/8 - f/11 refraction will reduce sharpness.
Figure out how you like your aperture to look in backlight situations... there are many more factors than sharpness at f/8 even for landscape photography.

[Digitalis]

f/8 - f/11 refraction will reduce sharpness.

I think you mean Diffraction - which is only a significant problem when diffraction causes the airy disk to spread out significantly past individual photodetector boundaries. There are sharpening techniques that can be used to counter diffraction softening that work with varying success, there is also shot stacking software that can allow you to increase DOF without the diffraction penalty. Tilt/Shift lenses used by someone knowledgeable on the Scheimpflug principle can extend DOF well beyond what the same aperture value on a fixed focal plane camera could achieve.

[motorhead9999]

Thanks everyone. I ended up going with a Pentax m 50mm f1.7

[LensBeginner]

Based on my tests on a SMC-M 50/1.7 on a couple of Pentax 16MP bodies, I've found the sharpest aperture to be f/5.6, f/8 being a whiff softer (probably due to diffraction).
I didn't test it on a FF body, so border/corner performance could be different (on APS-C it's sharp all over the frame at f/5.6), but, due to pixel density being the same between a 16MP APS-C body and Pentax FF models, degradation due to diffraction should be identical.

As already stated by others, performance at f/8 is largely meaningless in order to evaluate a normal lens.

[mikesbike]

Other than being able to control the aperture with the camera body, is there an advantage to the M vs A optically? Or is it just a build quality preference?

One thing at least is metering mode. You don't get matrix metering with M lenses or earlier. I have both M and later lenses, and much prefer the later AF lenses (basically same as "A" except for having AF) as they are much faster-responding than using the green button, which I also have found is not all that accurate and changes depending on which aperture is selected. Metering, even using spot or center-weighted, with A or AF lenses vs M lenses for me has been more accurate.

---------- Post added 10-31-19 at 09:12 AM ----------

There are more advantages with the FA 43mm LTD: build quality is first-rate, its MF feel is very good and smooth, perspective for shooting scenics is just as the eye sees it. Front-to-back ratio between objects or of the same object is accurate. There is no elongation or compression. This perspective accuracy was the reason for designing it with the odd FL- 43mm, which is especially useful on a FF body for which it was designed. I used mine for years with 35mm film. If I should get a K-1, it would again see more use. I think Pentax should upgrade this model by having HD coatings as they have with the FA 35mm f/2. Image quality is excellent.

With the FA HD 35mm f/2 you can get exceptionally fine edge-to-edge performance right from wide open on, and at a reasonable price. MF feel is ok, probably improved by the look of it on the newer HD version. Image quality is excellent across a large aperture range.

Even the DA HD 40mm f/2.8 Limited could be considered, especially for landscape use, as it has shown to have excellent edge-to-edge sharpness across its aperture range, even at f/11, to an exceptional degree! It is said to be cut large enough for FF use, and would be even smaller on a K-1 than the FA 43mm LTD, and far less expensive for a new one. It would look and handle phenomenally as a combo with the K-1, making for a "compact FF DSLR"! Again, build quality is first-rate and MF feel is very smooth. I use my older non-HD version on my KP, K-S2, or even on my larger K-5 IIs, but it would also see more use if I had a K-1, especially when I need top quality edge-to-edge performance. You'd need a different hood than the one supplied for APS-C coverage, due to the wider FOV on the K-1.

[yucatanPentax]

My first 50mm years ago was a Meyer Domiplan 50mm f/2.8. Despite a generally poor reputation (and lowish ratings here), it performed fairly well where I used it, which was f/8 and f/11, mostly. When I graduated to a Pentax with a M-50 f/1.7, I thought I'd died and gone to heaven.

Skip to years later, looking for a manual lens for my K200D (awhile back), someone on these Forums sold me another M-50 f/1.7. On digital it's every bit as good as it was years ago on film.

Now having an M-50mm f/1.4, I still favor the f/1.7 most of the time. Since that's what you seem to have chosen, I think you'll be happy with it. Still one of the best lenses I've owned because it is pleasurable to use. There's something satisfying about manual focus and slowed down photography.

[mikesbike]

I just thought of something else regarding the DA HD 40mm f/2.8 LTD. It is too small to have a MF/AF switch, but it does feature "quick shift" instant MF override when the camera is set to AF. This is very handy when shooting with AF but wish to instantly perform manual touch up focus, or bias for a particular area. It has received top-rated test reviews. Its newer multi HD coatings are said to reduce flare and ghosting, and additionally are anti-finger print and easier to clean.

[monochrome]

Thanks everyone. I ended up going with a Pentax m 50mm f1.7

Good choice!

To be honest the sharpest "Lady" in the Harem is my “Femme Fatale” (Pentax-A 50mm F2.8 Macro)... but don't tell the others as it can get quite bitchy.

The A/FA/DFA 50/2.8 Macros are crazy sharp, resolving 110 lpmm @ f/8 and f/11 in an old test on film. That compares to between 80 and 98 lpmm on various Pentax normals. You really can’t go wrong with a Pentax normal. I recommend the K55/1.8 on a price / resolution basis.


See the resolution test here: http://www.takinami.com/yoshihiko/photo/lens_test/pentax_normal.html

[Leumas]

Good choice!The A/FA/DFA 50/2.8 Macros are crazy sharp, resolving 110 lpmm @ f/8 and f/11 in an old test on film. That compares to between 80 and 98 lpmm on various Pentax normals. You really can’t go wrong with a Pentax normal. I recommend the K55/1.8 on a price / resolution basis.


See the resolution test here: http://www.takinami.com/yoshihiko/photo/lens_test/pentax_normal.html

Any idea what the lpmm is for the 50 f4 macro?

[monochrome]

Any idea what the lpmm is for the 50 f4 macro?

I don’t have any resolution tests linked, but my K50/4 Macro (and K100/4 Macro) is plenty sharp.