[tuco]

I can't see the images (blocked) right now but start stopping the lenses down. See which one still has round OOF background lights at f4 and f5.6.

[audiobomber]

\For instance, mechanically it would really benefit by adding Quick Shift, better AF and a better designed hood (preferably removeable, or at least retractable). Optically, it has a fair bit of purple fringing and longitudinal CA ("bokeh fringing"), which become pretty obvious when shooting wide open (necessary for shallow DOF) in high contrast conditions, even when viewed at normal sizes. In all these ways the Sigma 35 has a distinct advantage over the FA 31.

If Pentax could address these issues I mentioned, and add WR, making a DFA 31, that would make it a near-perfect lens. Oh and release a FF camera to mount it on.

There was a DA*30mm f1.4 on the 2008 lens roadmap. I would pay FA 31mm pricing for that. I'm not able to justify the cost for the FA 31 for the reasons you mention. I'm not interested in the Sigma because it's a Sigma. I'll keep using my FA 35 and DA 40 for now.

[Winder]

I've owned the FA 31 for quite some time, and it's one of my favorite lenses, but it's far from perfect. There are plenty of obvious ways it can be improved.

For instance, mechanically it would really benefit by adding Quick Shift, better AF and a better designed hood (preferably removeable, or at least retractable). Optically, it has a fair bit of purple fringing and longitudinal CA ("bokeh fringing"), which become pretty obvious when shooting wide open (necessary for shallow DOF) in high contrast conditions, even when viewed at normal sizes. In all these ways the Sigma 35 has a distinct advantage over the FA 31.

If Pentax could address these issues I mentioned, and add WR, making a DFA 31, that would make it a near-perfect lens. Oh and release a FF camera to mount it on.

Careful..... Implying that there is any weakness to a Limited lens, especially one of the 3 holy limited lenses, could get you banned here or worse.

But.... yeah.... the 31mm could use some updating to fix purple fringing, CA, modern coatings, modern AF.......

Does the Sigma 35mm require as much distortion correction as the 31mm, and what about light fall off at the corners?

[rparmar]

I've owned the FA 31 for quite some time, and it's one of my favorite lenses, but it's far from perfect. There are plenty of obvious ways it can be improved.

For instance, mechanically it would really benefit by adding Quick Shift, better AF and a better designed hood (preferably removeable, or at least retractable). Optically, it has a fair bit of purple fringing and longitudinal CA ("bokeh fringing"), which become pretty obvious when shooting wide open (necessary for shallow DOF) in high contrast conditions, even when viewed at normal sizes. In all these ways the Sigma 35 has a distinct advantage over the FA 31.

If Pentax could address these issues I mentioned, and add WR, making a DFA 31, that would make it a near-perfect lens. Oh and release a FF camera to mount it on.

I won't deny that you are right and note that I was being "somewhat" simplistic. I forget that people don't know me here anymore. ;-)

CA, long CA, and fringing exist in all the FA Limiteds, worst of all with the FA77. It sure would be good to get rid of those, but I can only imagine the price then! Plus the lens would be gigantic I am sure.

I agree the hood is bizarre.

But some of your points are a matter of personal preference. For example, I have never felt the need for Quick Shift since I can switch to manual focus quickly anyway. Better AF is not a property of the lens, I don't think. In any case, I would want the opposite... a lens with better manual focus handling (like a Zeiss or Tak) even if this meant AF disappeared entirely.

I would also give up some things for the lens to be smaller, and wouldn't want WR for that and aesthetic reasons. Only zooms need weather-proofing IMO. Does anyone need to shoot a special-purpose prime in the pouring rain? I bet it would survive anyway.

All things considered, there is still no equal to it.

Besides, surely the number one way in which the FA31 could be improved would be to offer it for $100!

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Last edited by rparmar; 06-03-2013 at 04:05 PM.

[Driline]

Besides, surely the number one way in which the FA31 could be improved would be to offer it for $100!

I'm with you there.

[tuco]

...
In any case, I would want the opposite... a lens with better manual focus handling (like a Zeiss or Tak) even if this meant AF disappeared entirely.
...

You'd be be giving up quick, candid shots when shooting more open on a FF camera. I looked at the Zeiss 35/1.4. It was not easy to focus and nail it fast shooting at f2.8 and wider. I had a dilemma. I wanted what the Zeiss rendered but I also wanted a snappy AF candid lens in the 35mm focal length.

I saw the Zeiss more of a specialty lens when compared to the Sigma. It would be nice to have both using each what it's better at. The Sigma's focus is pretty snappy on a FF Nikon.

[Cannikin]

But some of your points are a matter of personal preference. For example, I have never felt the need for Quick Shift since I can switch to manual focus quickly anyway. Better AF is not a property of the lens, I don't think. In any case, I would want the opposite... a lens with better manual focus handling (like a Zeiss or Tak) even if this meant AF disappeared entirely.

I would also give up some things for the lens to be smaller, and wouldn't want WR for that and aesthetic reasons. Only zooms need weather-proofing IMO. Does anyone need to shoot a special-purpose prime in the pouring rain? I bet it would survive anyway.

WR doesn't really change anything about the size or the aesthetics of the lens. Take a look at the DFA 100 Macro. It's WR, has a build virtually identical to the limiteds, and yet is easily the smallest lens in its class. Heck, it's even slightly smaller than its non-WR predecessor with the same optical design! There is simply no downside to WR, besides cost.

As for AF, screw drive performance is determined by the camera body of course, but the DC motor found in the DA 18-135 is truly a wonder. It's very fast, quiet and deadly accurate; never, ever have I gotten an out of focus shot with that lens (except when fallling victim to the K-5's excessively large focusing points). Also, decoupling the focusing ring from the AF system allows them to arbitrarily change the tactile feel of the ring. IMO the Sigma 35 and DA* 55, both with in lens motors, have nicer feeling MF rings than any screw drive lens I own.

The only potential downside to in lens AF would be added weight and size (and again cost), but many newer lenses like the Olympus 12mm f/2 are downright tiny (slightly smaller than the DA 15), and still manage to have an ultrasonic motor, a nice feeling MF ring (though focus by wire) and a full metal build. You can have small size, classic build, nice MF, and in lens motor all at the same time (but not cheap price sadly).

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Last edited by Cannikin; 06-03-2013 at 07:24 PM.

[Cannikin]

Does the Sigma 35mm require as much distortion correction as the 31mm, and what about light fall off at the corners?

I don't really have a setup to judge distortion or vignetting, but going by lens reviews like Lenstip's and Photozone's reviews of both lenses, it would appear that the Sigma has slightly less distortion and vignetting than the FA 31 on APS-C, something also suggested by the Lightroom lens profiles (though not sure if LR4.4 accurately reflects the Sigma on Pentax yet as it doesn't auto-detect correctly). In absolute terms, though, both are fairly negligible, considering they're both FF lenses. In my test photos I don't see any obvious signs of distortion or vignetting with either lens.

The real test is on FF of course. The distortion on the Sigma at least appears to remain fairly moderate, but the vignetting gets to a pretty extreme level wide open, easily visible in many sample photos I've seen. Unfortunately there's no FF tests available for the FA 31 for comparison (for obvious reasons).

[rparmar]

The only potential downside to in lens AF would be added weight and size (and again cost), but many newer lenses like the Olympus 12mm f/2 are downright tiny (slightly smaller than the DA 15), and still manage to have an ultrasonic motor, a nice feeling MF ring (though focus by wire) and a full metal build. You can have small size, classic build, nice MF, and in lens motor all at the same time (but not cheap price sadly).

Good reply that corrected some of my misconceptions.

Still, you can't have AF and a good manual focus feeling at the same time. Because you need lots of resistance for MF and motors can no longer drive the helicoid in that case. You are good to bring up the Olympus 12mm, which is the best attempt any manufacturer has yet made to bridge this gap. I tried it in-store only, so my opinion is not worth much. But I thought it lacked a lot in feel due to focus by wire. It is not going to compare to Leica, Zeiss, Takumar, Pentax K, M, or even A.

It's also pretty darned expensive for a lens that's fugly silver. ;-)

[thibs]

Good reply that corrected some of my misconceptions.

Still, you can't have AF and a good manual focus feeling at the same time. Because you need lots of resistance for MF and motors can no longer drive the helicoid in that case. You are good to bring up the Olympus 12mm, which is the best attempt any manufacturer has yet made to bridge this gap. I tried it in-store only, so my opinion is not worth much. But I thought it lacked a lot in feel due to focus by wire. It is not going to compare to Leica, Zeiss, Takumar, Pentax K, M, or even A.

It's also pretty darned expensive for a lens that's fugly silver. ;-)

IMO you can have acceptable MF feel with AF lenses e.g. Da*50-135 but focus by wire though... no MF is better. What a junk.

[Cannikin]

Hey guys, as requested I came up with a quick blind comparison for the bokeh, in which they were normalized as much as possible. I posted it here in a separate thread, so I could add a poll: https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/228193-bokeh-b...igma-35-a.html

[Emacs]

No-one's ever going to find a better lens than the FA31.

I own one. It is way too expensive though

[mrNewt]

I'd buy whatever is cheaper... they both seems to do the job just fine (slightly interested more in the Sigma rather than Pentax).
Size wouldn't be a problem for me.

[Mgrajkumar]

The 2 copies I received has heavy front/back/infinity focus issue. AF is not good under low light, pictures are sharp only if you take through LIVE VIEW.