[Edgar_in_Indy]

Your best shot is the Pentax FA31 Limited. There isn't a single lens from any manufacturer that is truly "razor sharp" at f/1.4 that doesn't carry a price tag over $2000.


[In regards to the Sigma 30mm 1.4):

Everything else outside the center even at f/11 is complete rubbish...

I'm not sure how an f/1.8 lens is his best shot at getting razor sharp at f/1.4. But in regards to the Sigma 30mm f/1.4, Photozone (a site which seems to obsess over sharpness) said the following:

"The image center showed a superb performance reaching and probably exceeding the image sensor resolution of the EOS 350D (8MP) - even at f/1.4 the center is already excellent."

True, the edges aren't the best out there, but you're not gonna have good edges at 1.4 on any lens that can be used with our cameras. And I know that you hate the Sigma 30, but I've gotten some really great pictures from it. And that's a lens that I actually do use at f/1.4 from time to time.

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Last edited by Edgar_in_Indy; 01-17-2016 at 03:16 PM.

[Rondec]

f1.4 lenses are problematic in that they may be sharp at f1.4 but there is little in focus at f1.4 so that they appear soft. I have found the DA *55 to be usable wide open, although I prefer it at f1.8.

This is my daughter at f1.4 with the DA *55



And my other daughter (this one shows how the highlights/bokeh can get really weird with the DA 55 wide open)



The FA 77 is quite usable wide open at f1.8 (wide open).





---------- Post added 01-17-16 at 04:30 PM ----------

I'm not sure how an f/1.8 lens is his best shot at getting razor sharp at f/1.4. But in regards to the Sigma 30mm f/1.4, Photozone (a site which seems to obsess over sharpness) said the following:

"The image center showed a superb performance reaching and probably exceeding the image sensor resolution of the EOS 350D (8MP) - even at f/1.4 the center is already excellent."

True, the edges aren't good, but you're not gonna have good edges at 1.4 on any lens that can be used with our cameras. And I know that you hate the Sigma 30, but I've gotten some really great pictures from it. And that's a lens that I actually do use at f/1.4 from time to time.

I owned the Sigma 30mm f1.4 and in my humble opinion, the FA 31 is much more usable lens in every day situations. I found the Sigma usable as long as I put the subject in the center of the frame or stopped down quite a bit, but if you want to compose differently than that sometimes (and who doesn't) then, you need a lens that has a little more border sharpness.

I think in that regard the Sigma 35 f1.4 is hands down a better lens, although some have expressed that it has some issues focusing on Pentax cameras.

[hjoseph7]

I think your best bet would be Sigma 35mm f1.4 Art. Probably the sharpest lens that I have seen for Pentax. Now, I don't exactly know how do you define razor-sharp, but in my book my copy is very sharp from f/1.4. Price should be below 1000$.

Those two pictures below are at f/1.4. Keep in mind that I was using AF handheld and my copy sometimes has FF/BF issues, so the focus might not be correct. I am sure I can do better on a tripod with Contrast AF in Live View, for instance.





Check the review of this lens here.

That is pretty sharp for F1.4 but I think that on a APS-C camera that's really not f1.4 probably closer to f2.

[Rondec]

That is pretty sharp for F1.4 but I think that on a APS-C camera that's really not f1.4 probably closer to f2.

No, it is f1.4 regardless of the size of the sensor. This is a full frame lens and if you stick on a full frame camera, snap that photo and then stick it on a crop camera and snap the same photo, the only difference is that the crop sensor has cropped the edges away. But it is still a 35mm f1.4 lens shot at f1.4.

[Edgar_in_Indy]

That is pretty sharp for F1.4 but I think that on a APS-C camera that's really not f1.4 probably closer to f2.

Oh boy, here we go. Or rather, lets not. If I could vote you down somehow, I would, just for opening that tired can of worms.

I owned the Sigma 30mm f1.4 and in my humble opinion, the FA 31 is much more usable lens in every day situations. I found the Sigma usable as long as I put the subject in the center of the frame or stopped down quite a bit, but if you want to compose differently than that sometimes (and who doesn't) then, you need a lens that has a little more border sharpness.

Here's a picture from my Sigma 30mm shot wide open at f/1.4 with two subjects, neither of which is in the center! Click for the full-size 1:1 image. To me, it's pretty outstanding for f/1.4. I've shared this pic before, so I'll save myself some typing and just copy what I said in the past:

Maybe I got a really good copy, but in my experience the complaints of edge softness are over blown. It's sharp in the center, as well as a significant portion of the frame, even if it is not great at the far edges.

Here's a picture from the recent birth of my third daughter, shot with my 30mm wide open at f1.4. Click on it for the full size version, and look at the nurse's face, and the texture of the face mask and hair cover. Even though it's close to the edge of the frame, it still has good sharpness with plenty of detail. Mind you the picture was shot wide open with an f1.4 lens that can be had for ~$300. For my uses documenting my family, the Sigma 30mm is fantastic.

So I guess the moral of the story is don't put your subject in the very corner and then shoot at f/1.4, and you'll be fine. At least with my copy.

f1.4 lenses are problematic in that they may be sharp at f1.4 but there is little in focus at f1.4 so that they appear soft. I have found the DA *55 to be usable wide open, although I prefer it at f1.8.
...

I use the Pentax DA 50mm f/1.8, suits me fine - by the way, where's that patriotic statue located, surely not Indiana; is that one at VMI?

https://www.flickr.com/photos/85914716@N03/23561787013/

[Digitalis]

'm not sure how an f/1.8 lens is his best shot at getting razor sharp at f/1.4.

It is, by far one of the the best performing, currently in production pentax branded lenses at f/1.8. On the Pentax K5IIs it delivers good, perfectly usable image quality across the 16mp frame - in fact, in terms of resolution at 31mm it beats the Sigma 18-35mm f/1.8 ART at f/1.8.

EOS 350D (8MP) - even at f/1.4 the center is already excellent.

let us continue with that quotation shall we: "Unfortunately the borders and more so the extreme borders are never really able to catch up. At f/1.4 borders are extremely soft. As usual the situations improves towards medium aperture settings but not overly so."

And on higher MP camera bodies the deficiencies in corner sharpness of the the Sigma 30mm f/1.4 EX will be even more obvious. I don't think my hatred for this lens in unjust: it is intended to be the APS-C equivalent of the classic "normal" 50mm class of lenses. However, unlike a majority of classic 50mm lenses of which I have a considerable amount of experience with: it fails to produce image quality that equals the average 50mm lens, most of which perform superbly from corner-to-corner at f/5.6. Even at f/11 the Sigma 30mm f/1.4 EX fails to meet the standards set for it.

I have two of the FA Limiteds (FA 43 and FA 77) I was thinking to complete the circle and get the FA 31 also. Do you think this is justified considering that I have the Sigma 35 f1.4 ?

It is entirely up to you, but being one short of a trio of limited lenses, you will always be wondering if you would find the rendering of the FA31 to be more agreeable compared to the Sigma 35mm f/1.4 ART. Personally, I work with the Sigma 35mm f/1.4 ART* on my Nikon cameras and technically it is a superb lens, but it is a bit soulless in its rendering. The FA31 on the other hand can almost turn any mundane scene into art.

*I predominantly use the Carl Zeiss 35mm f/1.4 when I don't need AF. The Zeiss lens has a cooler colour rendering than sigma lenses which some of my clients find desirable.

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Last edited by Digitalis; 01-17-2016 at 06:07 PM.