FA 31 Limited - why is it so good?

lens is only as good as the photographer using it....
some people instantly think that a pro lens will get make them a better
photographer .. not the case

Nonetheless some lenses perform better than others in a technical sense, but it all depends on what the desired effect is as to whether a lens is "better".

If you want soft focus, look for an old rubbish lens that's full of flare. If you want to reproduce documents, look for a macro lens. This is why over the years I've found lenses that I like and those I don't like.

I don't like:
SMC Pentax-M 50mm f/1.4
SMC Pentax-M 85mm f/2
SMC Pentax-M 120mm f/2.8

I do like:
SMC Pentax-M 50mm f/1.7
SMC Pentax-M 100mm f/2.8

Just to take some examples out of the M series range. I'm sure that others will have different preferences. Unfortunately the only real way to get to know a lens is to own it and use it. This has been an expensive business for me over the years.

Of the three FA Limited lenses though, my favourite is still the 43mm, despite its technical performance on paper being the lowest.

I was wondering what it is about the Pentax-M 50mm F1.4 that you don't like John? I have this lens and find that although it's not as sharp as say a F1.7, it renders colours beautifully and produces very pleasing results.

Harking back to the earlier posts in this thread, a few people have mentioned that a number of the earlier K-mount lenses have the 'pixie dust' magic. For this reason they can be relatively expensive (in comparative terms against other old manual focus lenses). The bargains for me have to be the M42's, many of which have the the same optical formula as the early K's. I don't own too many of the older ones, but two for me that have the magic are the SMC K135 F2.5 and the SMC Takumar 135mm F3.5. The Tak cost me £20 but produces wonderful warm, fluid images. For such a cheap lens it's a marvel.

Regards
David

The SMC Pentax-M 50mm f/1.4 is sharp and contrasty, making it an ideal low light and reportage lens. Where I like it less is the relatively harsh rendering and the lack of gradation in finer details.

I'm really thinking here in terms of black and white. In terms of colour I find the SMC Pentax-FA 50mm f/1.4, its latest incarnation, to be OK but just a little bland.

The 43mm f/1.9 seems to share more of the warm quality I like about the older 50mm f/1.7 lenses, or indeed the even earlier f/1.8 ones.

I agree that one cannot judge fitness to task until one knows what the goals are. However, most people underestimate what can be read from specifications. Unfortunately Pentax does not publish proper MTF 5, 20 and 40 graphs (unlike Leica, for example) so we are left in the dark or reliant on third-party tests. These are also often incomplete and impossible to compare across labs.

With proper graphs we can even make statements about bokeh quality, etc. Erwin Puts' documents for Leica are make fascinating reading in this regard. Though specs may not say everything about how the lens renders, they do say a lot more than most casual photographers realise.

This reality doesn't accord with the ideologies of individuality and subjectivity that many ascribe to. People would rather think it's all about them! (Lens designers know otherwise. After all, contemporary lenses are designed from start to finish on the computer.)

I made a study of this matter some time ago and must say this statement is not true. The FA31 has the same rather poor distortion and CA qualities of the FA43. And the FA43 has higher peak MTF 50 than either of its brethren. All have poor purple fringing, but especially the FA77.

So my conclusion is the opposite of yours: the FA43 has the best specs on paper of the three.

I don't have references to hand but check out ePhotoZine and PhotoZone, both of whom have published test results.

I'm not sure you read my statement properly rparmer - what I said was that my favourite was the 43mm, so how you contend that it isn't true?

As regards the tests, the samples I had are available to view as EPZ reviews and that is what I said about performance on paper, not specs on paper, which would be a different thing altogether.

I don't need to check out the EPZ published reports, mainly because I wrote them....

Where did I say it was untrue that your favourite was the FA43? I quoted the entire statement to comment on the second clause. This is obvious from the fact that all my statements are about the second clause. How could you possibly think I was arguing with what your favourite might be? Especially as I share this opinion! Truly bizarre.

You seem to think that because I am replying to a post you wrote I am writing only to you. Not so, I am writing to everyone who may be reading this thread. Otherwise I would send you the info in a private message. Not all the readers here will have the same facts to hand as yourself. I would have thought you'd have been happy to have your own article referenced (it's here), but instead you use this as yet another reason to pick a fight with me. How very odd.

In any case, if you compare the MTF50 charts for the FA43 and FA77 (something that should be dead easy for you to do since you are so familiar with the ePhotoZine articles) you will see that the FA43 has higher peak values both at f/2 and at its best aperture. It even has higher weighted values at f/2, despite its notoriety for poor corners. Apart from this, the FA43 has highest MTF20 in the centre, across apertures. And less tendency to purple fringing, though CA is high.

Thus your statement "despite its technical performance on paper being the lowest" appears to be false, based on the very tests you are familiar with. The FA77 actually has lower performance. That is the claim I made, which I didn't think needed this sort of elaboration (since anyone can compare the values they find important for themselves).

The only other possibility is that you are now using "performance" in a way others do not. I find this unlikely, since in the article in question the section headed "performance" does indeed examine, among other things, these MTF charts I am using as evidence.

And no, this argument does not imply that I think these differences are significant. Nor does it imply that I think one should judge lenses based on lab bench tests. Nor does it have any immediate bearing on the FA31, a lens I do not own and so will not compare in this fashion. Others may wish to do so.

This discussion had become very technical for me - for me the best answer was provided by David Holmes, very early on

Pixie dust you mean? That's the most likely explanation....

Well no technical explanation can explain why something is good.