[Edgar_in_Indy]

I wouldn't go much shorter than 30mm for portraits because of perspective distortion.

The OP is wanting the lens to do full and 3/4 body shots indoors, not full-frame head shots.

[robgo2]

I don't think a 43mm is really a clear answer to someone looking for a lens a good bit wider than 50mm.

Your suggestion of the 31mm 1.8 ltd was a good one, but it's kind of hard to make a case for it when the lowest price online is $989.95 (Adorama), and the excellent Sigma 30mm 1.4 can be had for less than half the price at $454.99 (42nd Street Photo). Not to mention the fact that the Sigma is 2/3 stop faster.

I have the Sigma, and I do spend a lot of time at f1.4, so I would definitely miss it. With a wider angle like the 30 or 31mm, you need to use a very large aperture to induce bokeh in lot of situations, so the 1.4 is very useful.

I'm glad your lens is producing results that please you. I have no personal experience with the Sigma 30/1.4, but Photozone tested it and was not impressed with its optical quality (2 stars out of 5). Center sharpness was good, but that's about it. Read the review here: Sigma AF 30mm f/1.4 EX DC (Pentax K) Review / Test Report. More to the point, Photozone says of the 30/1.4: "So did it beat the real thing (Pentax SMC FA 31mm f/1.9 Limited) ? No, it did not."

I would add that the Sigma almost certainly does not have the rendering qualities of the FA Limiteds. Few lenses do. Yes, it is considerably less expensive than the FA 31 Limited, and that would seem to be the only reason that one might choose it.

Back the OP, the choice of focal length is up to you, but you will never regret owning either the FA43 or FA31.

Rob

[newarts]

The OP is wanting the lens to do full and 3/4 body shots indoors, not full-frame head shots.

Oops! I forgot that! I wonder if there's an effective distortion limitation on framing distance for a 3/4 or full portrait?

I'll guess that 2meters from a 2meter high portrait is too close (if I stand 2m from a 2m high subject I can't see it all well at a glance). That corresponds to about a 25mm lens, which is again consistent with the DA 31.

[Edgar_in_Indy]

I'm glad your lens is producing results that please you. I have no personal experience with the Sigma 30/1.4, but Photozone tested it and was not impressed with its optical quality (2 stars out of 5). Center sharpness was good, but that's about it.

It's not a perfect lens, but I was well aware of its limitations going in. But to just say that center sharpness was "good" though, is selling it a bit short, and doesn't tell the whole story. To quote the same review:

The center resolution is already on a very good level at f/1.4 and f/2 and reaches excellent and even absolutely outstanding levels beyond. (emphasis added)

It's not often that you see Photozone use the term "absolutely outstanding" when talking about lens sharpness. Most 1.4 lenses are very soft wide open, and have to be stepped down a good bit to get good sharpness. The Sigma 30mm, though, is already very sharp in the center wide open at 1.4. According to the Photozone resolution charts, the Sigma 30mm 1.4 is as sharp in the center at 1.4 as the legendary Pentax 31mm is at 1.9. Very impressive stuff in my book.

Of course, every lens is a set of compromises, and the Sigma 30mm is no different. The big compromise with that lens is sharpness that lags in the corners. I didn't really see this as a big deal, since at large apertures, most of the frame will usually not be in focus anyway, so the corner sharpness isn't going to be particularly noticeable. But for certain kinds of photography, such as landscape or architecture, this wouldn't be an ideal lens since you would want good, consistent sharpness across the whole frame.

But for full body or 3/4 portraits, as the OP is wanting to shoot, the corner performance isn't going to be a big deal, since his focus wouldn't generally be at the edge or corners of the frame. This is the type of photography where the Sigma 30mm excels.

[Edgar_in_Indy]

Oops! I forgot that! I wonder if there's an effective distortion limitation on framing distance for a 3/4 or full portrait?

I don't know the science, but my experience has been that a wide lens can be fine for a full or upper body shot, but should be avoided for a tight head shot.

[robgo2]

It's not a perfect lens, but I was well aware of its limitations going in. But to just say that center sharpness was "good" though, is selling it a bit short, and doesn't tell the whole story. To quote the same review:

The center resolution is already on a very good level at f/1.4 and f/2 and reaches excellent and even absolutely outstanding levels beyond. (emphasis added)

It's not often that you see Photozone use the term "absolutely outstanding" when talking about lens sharpness. Most 1.4 lenses are very soft wide open, and have to be stepped down a good bit to get good sharpness. The Sigma 30mm, though, is already very sharp in the center wide open at 1.4. According to the Photozone resolution charts, the Sigma 30mm 1.4 is as sharp in the center at 1.4 as the legendary Pentax 31mm is at 1.9. Very impressive stuff in my book.

But center sharpness was practically the only thing that Photozone could find to praise in the Sigma 30/1.4, optically speaking. You must admit that the review was very unenthusiastic overall. And the fact that it pointedly compared the Sigma unfavorably to the FA31 speaks volumes to anyone who is considering the two lenses.

Rob

[Edgar_in_Indy]

But center sharpness was practically the only thing that Photozone could find to praise in the Sigma 30/1.4. You must admit that the review was very unenthusiastic overall. And the fact that it pointedly compared the Sigma unfavorably to the FA31 speaks volumes to anyone who is considering the two lenses.

What you say is true, but it should be remembered that the Photozone reviews are written from a general-purpose photography perspective, and there are some types of photography where the Sigma 30mm would be a downright bad choice due to lack of edge-to-edge sharpness. This must figure into their ratings, since they specifically mention "general purpose photography" in their closing paragraph. The OP, however, said they were looking for a lens primary for people pictures.

I think that if the review was evaluating the lens primarily for the portrait photographer, the Sigma 30mm would fare much better. Particularly for an available-light photographer who will mostly stay between f1.4 and f2. And the 1.4 aperture will give you a noticeable advantage when shooting in dim light. It may allow you to shoot at ISO 800 instead of 1600, or make a shot handhold-able where it otherwise would not be, or increase your shutter speed enough to avoid motion blur in your subject.

I pretty much only use my Sigma 30mm when shooting people using available light. When I'm in a situation where I want edge-to-edge sharpness, I can always go for my Tamron 28-75mm 2.8 or probably even my Pentax F 50mm 1.7. I have a home studio outfitted with strobes for portraits, and I also shoot a lot of product pictures for eBay, and in those situations I would never even think of using my Sigma 30mm.

Now if somebody offered me the Sigma 30mm or the Pentax 31mm for the same price, I don't think I would turn down the Pentax. But for most people, price probably will be a factor. And for someone who is primarily a portrait photographer, I think it would be hard to justify the premium for the Pentax. Personally, I would rather buy the Sigma 30mm 1.4 (obviously ), and use the money I saved to buy something fun, such as a super-wide zoom or a good flash.

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Last edited by Edgar_in_Indy; 04-07-2012 at 12:12 PM.

[robgo2]

Now if somebody offered me the Sigma 30mm or the Pentax 31mm for the same price, I don't think I would turn down the Pentax. But for most people, price probably will be a factor. And for someone who is primarily a portrait photographer, I think it would be hard to justify the premium for the Pentax. Personally, I would rather buy the Sigma 30mm 1.4 (obviously ), and use the money I saved to buy something fun, such as a super-wide zoom or a good flash.

Of course cost is a consideration for most people, but taking it out of the equation, the FA31 is the clear winner. I have no idea if the FA31 or the FA43 is within the OP's budget.

Rob

[Edgar_in_Indy]

Of course cost is a consideration for most people, but taking it out of the equation, the FA31 is the clear winner.

Yes, if price is not relevant, then the FA31 would be the clear winner...assuming the buyer didn't mind having f/1.8 instead of f/1.4.

[Edgar_in_Indy]

I was looking at the two Photozone reviews for the Sigma and Pentax, and noticed that the two reviews had a couple of sample images that featured the same subject and composition. The lighting is different, but if you keep that in mind, I think they can still be useful for comparing the two lenses. Here are small versions of the images that you can click on to open the original, full size images:







After studying these images, and obscenely pixel-peeping them, I must say that I'm not seeing where the Pentax noticeably outshines the Sigma, except wide open at the extreme borders. Both sets of images look very good to me in terms of sharpness, contrast, bokeh, and color.

I think the gate image looks very good from both lenses. It's possible that the Pentax has slightly more pleasing bokeh in this instance, but it's kind of hard to make an exact comparison, since the leaves on Pentax image are bathed in sunlight, whereas on the Sigma image the leaves are in shadow. Also, the Sigma is at 1.4 while the Pentax is at 1.8, so it wouldn't really be an apples-to-apples bokeh comparison anyway. The big difference in this image is the leaves at the very bottom of the frame that happen to fall into the narrow field of focus. On the Pentax, those leaves along the edge are much sharper than the Sigma. The situation would be somewhat improved for the Sigma if it was also at f1.8, but the Pentax would still have the advantage here.

In the church image, the tree branches in the extreme upper-left corner probably look a bit better on the Pentax than the Sigma, but if you look at the church itself, it seems to me that the Sigma is noticeably sharper. This is most obvious in the bricks, and especially the details of the windows. Even the grass in front of the church looks like it has a little more detail in the Sigma image. And moving close to the edge of the frame, to the larger ball on top of the steeple, I don't see where the Pentax has a sharpness advantage.

I'm surprised that the Sigma would look sharper over so much of the frame, because according to the resolution charts, both lenses peak at f4, and then start to go downhill. But the Sigma church image is shot at f10, while the Pentax image is shot at f8, closer to the resolution sweet spot. But then again, the Photozone resolution charts do show the Sigma achieving a higher maximum resolution, so perhaps this should not be so unexpected. I wonder how the comparison would have been if both lenses were at f8.

But my point in all of this is that in the real world, the image quality differences between these two lenses are not nearly as pronounced as the lab tests might indicate. And it looks like what the Sigma gives up at the edges, it regains in the center.

For easy reference, here are links to the two Photozone.de reviews:

http://www.photozone.de/pentax/145-sigma-af-30mm-f14-ex-dc-pentax-k-review--test-report

http://www.photozone.de/pentax/122-pentax-smc-fa-31mm-f18-al-limited-review--test-report

[joe.penn]

I think the gate image looks very good from both lenses

The Siggy shows quite a bit sharper wide open going by the gate photos; this could be due to the extra amount of light though giving it the edge in sharpness.

[Edgar_in_Indy]

The Siggy shows quite a bit sharper wide open going by the gate photos; this could be due to the extra amount of light though giving it the edge in sharpness.

I thought so too, but I didn't mention it since it's kind of hard to tell with the focal points being different. But it appears to be at least as sharp at f/1.4 as the Pentax is at f/1.8.

[Kennod]

I do indoor portraits moslty kids and family sessions outside I find I have to back up so much to get full or even 3/4 body shots

I'm not sure why we are comparing shots of churches and gates.

For 3/4 body shots, the 35mm focal length is perfect. The DA 35/2.8 Macro is great, as is the FA 35/2. The much cheaper DA 35/f.2.4 is optically just as good as the FA version.

You really have little to lose trying the DA 35/f2.4. It doesn't look like a top-end lens, but it can produce top end quality with lightening fast autofocus on your K-5.

[Edgar_in_Indy]

I'm not sure why we are comparing shots of churches and gates.

I realize you were likely being facetious, but since you asked...we're comparing churches and gates because these are almost identical shots that are available from the two lenses that were under discussion, and they work just fine for comparing image quality. And unless there's some obscure law of physics I don't know about, a lens that will take a sharp picture of a church or a gate will also take a sharp picture of a person. Thanks for asking though.

The FA 35mm f2 is certainly an interesting recommendation. What do those go for?

**EDIT**
I just checked, and the cheapest I can find an FA 35mm f2 new is on Amazon for $550. Looks like they go used on eBay for around $350. It seems to be a very capable lens, but I would still go for the Sigma for its better low-light capabilities and narrower depth of field.

[Kennod]

unless there's some obscure law of physics I don't know about, a lens that will take a sharp picture of a church or a gate will also take a sharp picture of a person.

It's not just about physics and absolute sharpness though is it? Sharpness is definitely important, but for portraits, pleasing bokeh and rendering of skin tones is really what makes one lens preferable for portraits than the other. These are of course subjective qualities, but I would always choose my FA 77 over my DA 70 for portrait even though the DA has better edge-edge sharpness and minimal aberrations.

Anyway, was just suggesting to the OP that for 3/4 length portraits that there are some good value for money options at the 35mm focal length.