[Eigengrau]

Some camera bodies are more forgiving than others.

I'm going to be using this on a K100D at first, but either a K20 or a K??? in a little while depending on what Pentax launches at Photokina.

[beaumont]

Can't speak to the other lenses but I have the 31 and love it. (So much so that I am currently targeting the sibling 77 as that is a focal length that seems to be my current sweet-spot.)

[K100Dave]

I have never used any but the DA 35 LTD, and it hardly leaves my camera only for the DA 70 LTD. I hear that the FA 31 LTD is the Pentax standard in primes, if you can afford it tho.

[wavecurrent]

I gave the FA35 my vote, waiting for it to arrive Order one new yesterday

Mike

[Marc Sabatella]

That sounds like a little jab and fair enough! I should point out though that my liking for smaller focal lengths does not stem from the mathematics -- that is only a justification after the fact. I like the 28mm range because it feels right, seeming to capture a natural field of view without any distortions and "strains".

But this appears to be at least somewhat subjective. I like 28mm on APS-C too, but it feels "wide" to me. 40mm feels *perfect* - way more often than not exactly what I expect when I lift the camera to my eye. And this is true even for shooting landscapes, when many if not most people prefer even wider than 28mm.

But then, I suspect my experience as a landscape painter has colored my thinking, where I'm always tending to think it terms of what seems "paintable", and this often requires focusing on a narrow angle of view than one might take in on a more casual scan of a scene.

In fact just today I did a painting, and took a reference photo with my 18-55 just after I finished the initial sketch. Sure enough, like *many* of my pictures taken after selecting a scene to paint, it was right at the 40mm mark.

So anyhow, between that and the fact that I love the size of the thing, and of course the price can't be beat, I'd pick the DA40 from the choices given.

[rparmar]

It's good hearing your feeling for a view as informed by painting. Yes, I admit it is subjective, but something else must be going on here given the dominant use of certain focal lengths. Of course there is no reason to give in to a "dominant" position -- far from it! I am glad you have found what works for you and can articulate your position.

On full frame 28mm and 35mm were the common wide angles. I do like the equivalent FOV 16mm a lot for landscapes, as used on my DA16-45 zoom. The upcoming DA15 Limited covers this length. This leaves only the equivalent to 35mm unavailable. I suppose the DA21 Limited is close, but a faster 24mm lens would not be out of line, and would indeed fill an important gap in the prime lineup.

We are all different photographers and I have no interest in the DA40. Even my FA43 gets little enough use and it has godlike rendering.

I am happy with 105mm, though that might have something to do with a specific lens I own.

[Eigengrau]

I'm thinking maybe the DA40 would be "future-proof" in a sense - Pentax won't be making any 40's in the near future, the size puts it in a category of its own (so even with a full-frame sensor or a better 40 this will still be useful) and it is really cheap even to begin with. I've heard it focuses pretty quick because of the tiny focus group, too. And, it doesn't really count as taking up a lens spot in the bag since it can easily be slipped into a pocket or alongside another lens.

Of course I have to admit that Marc's post was pretty persuasive - I wonder, which focal length most closely matches the magnification of the human eye on a cropped sensor - so you could open your other eye and see a similar view?

Anyways I see that purchase as one that would be really hard to regret.


Any problems with my reasoning? The polls seem to disagree with me.

[Marc Sabatella]

Pentax won't be making any 40's in the near future

I'm not sure what you mean by this? The DA40 is still very much in production.

Of course I have to admit that Marc's post was pretty persuasive - I wonder, which focal length most closely matches the magnification of the human eye on a cropped sensor - so you could open your other eye and see a similar view?

The thing is. it is *not* about magnification. At least, it shouldn't be. Consider, the same lens on a camera with a tiny viewfinder and one with a very large viewfinder will produce *exactly* the same image, but it will *look* much bigger when looking through the latter viewfinder. The lens that happens to produce "normal" magnification is going to vary depending on the viewfinder, but that *should* have no relevance at all. Of course, it is tough not to be swayed by that to some extent - if things look too big or too small, it is gong to take a moment to adjust.

But really, what I am talking is not *magnification*, but *angle of view*. In other words, not how "big" objects look, but how much of a scene I can see at once. And I'm not the physical limits of human eyesight. Actually, we see *a lot* more than a 40mm lens can take in. More than the 18-55 can take in at 18, in fact. If you have the 18-55, set it all the way to 18 and look through the viewfinder. Unless you have serious problems with your peripheral vision, you can certainly see more of the scene in front of you with your unaided eyes than you can looking through the viewfinder.

But at some level, while we can *see* more of the scene than an 18mm lens can show, we normally cannot "focus" on all of it. There is a sort of *conceptual* angle of view through which we tend to view the world, and I'm sure it is very subjective - depending both on the person as well as the situation.

As a typical example, though, if I stand on my back porch and look at a tree on the other side of yard, I can see that entire tree and probably about 80% of my entire yard, including the bushes surrounding the tree, the hammock a few meters to my right, a smaller tree a few meters off to my left, some of the sky above the tree as well as to either side, good chunk of ground between me and the tree, etc.

And yet conceptually, I am really only *looking at* the tree - and probably just a portion of it at that (either the trunk at eye level or the canopy, but at this distance, not both at once). Similarly, I am only truly *aware* of a limited amount of its surroundings - just the foliage to either side of it and a small patch of the ground in front, perhaps.

My guess is that on APS-C, I can physically *see* close to the same angle of view as a 15mm lens. But no way do I really focus on nearly that much. Somewhere around the equivalent of 40mm is the amount of a scene I normally "focus" on at a time. Could be a bit wider if I am deliberately trying to take in a whole room, could be a bit narrower if I am trying to focus on a single person in that room, could be *lot* narrow if i am trying to focus on something in the distance. But it seems on average, I spend much of my life looking at things as if I were looking at the angle of view provided by a 40mm lens, as evidnece by the fact that I use focal lengths around there a *lot* with my 18-55, and the fact that, as I said, I am so seldom surprised by what I see when I put the camera to my eye with that lens mounted, whereas my 28 often seems wider than I expect and my 50 often seems narrower. The 28 fits my expectations more often in wide open landscapes - maybe a bit wider (24 or so). The 50 often fits better when looking at a single person. But the 40 fits my expectations the most often.

Anyways I see that purchase as one that would be really hard to regret.

The DA40? I'm not going to argue with that. Easily my favorite lens.

[Eigengrau]

I'm not sure what you mean by this? The DA40 is still very much in production.

What I was saying about no more 40's is - there's a rumored 30 DA* and a 55 DA*, while there are no indications that the DA40 is going to be superseded by an SDM DA* model in the near future. The fast 50 or the FA 31, OTOH, might be made redundant for photographers who want only one lens of a given length. Like having the old kit lens, or buying a macbook the day before they upgrade... true story.

The thing is. it is *not* about magnification.

Magnification might not be the perfect term, but field of view isn't complete either - our eyes don't compress depth like an extreme telephoto. Focal length might be more meaningful, but even that causes problems with different formats. On top of that, the eye also has a specific aperture range - 2.1 to 8.3, apparently. Some lenses will be a more natural match for what the eye sees than others.

While we have a relatively huge angle of view with peripheral vision, the portion of our vision that can actually render detail very well is comparatively small - things like reading are nearly impossible without looking directly at something - try to make out letters 5 lines above the one you're looking at, and it's pretty obvious. This is a result of cone density, which is by far the most concentrated at the center of the eye. Eyes are pretty "soft at the corners" so to speak.

I guess what I'm getting at, is I think there are some focal lengths that correspond to the effective portion of vision better. And it is true that those lengths match the magnification of the eye, just as much as they match the field of view and aperture.

[Marc Sabatella]

While we have a relatively huge angle of view with peripheral vision, the portion of our vision that can actually render detail very well is comparatively small - things like reading are nearly impossible without looking directly at something - try to make out letters 5 lines above the one you're looking at, and it's pretty obvious. This is a result of cone density, which is by far the most concentrated at the center of the eye. Eyes are pretty "soft at the corners" so to speak.

I guess what I'm getting at, is I think there are some focal lengths that correspond to the effective portion of vision better.

Yeah, that's my point too, except that I am saying there is also a phsychoogical compent as well as this physiological one. The bottom line being, this is pretty subjective - it's kind of ridiculous to assume that any calculation involving sensor diagonal size could ever yield *exactly* the "right" answer.

And it is true that those lengths match the magnification of the eye, just as much as they match the field of view and aperture.

Well, they match magnification only if your viewfinder happens to be the right size. A 50mm lens on my wife's old K1000 (full frame) camera shows a scene *much* larger than a 35mm lens on my K200D because the K1000 viewfinder is *much* larger, but the angle of view is virtually identical. And when I set the zoom on my tiny Canon S100 to the same field of view, the scene is downright *tiny*, but again, the angle of view that will be capture is the same. So all three will produce the same print, but it's really easy to get fooled by the viewfinders into thinking otherwise. You should choose a focal length primarily based on the angle of view it provides (well, with some attention to DOF and so forth too, of course), not the size in the viewfinder.

[Shashinki]

I wonder why "all of the above" is not an option. hehe

[beaumont]

Has the 31 ever been beaten in any of these polls (price aside)?

[Eigengrau]

Has the 31 ever been beaten in any of these polls (price aside)?

Well, seeing as how it has twice the votes of the next nearest competitor, I think the consensus is pretty clear. I wonder how much of it is expensive = better bias, though.

That said, I wouldn't expect the Pentax crowd to be particularly persuaded by that reasoning, because shooting Pentax is a counterexample in and of itself...

[Blue]

What I always wonder is how many people actually have or had 2 or more of the lenses in the poll.

[architorture]

here's another one that would fit right in the list:

Pentax Lens Review Database - 30mm F2.8

i only just discovered its existence yesterday

seems to be well-regarded, though not much opinion because of its rarity. a little pricey currently (hopefully not moreso now that i've brought it up).

since i realized it existed, i've been thinking that the new da* might be a reissue of this old smcp-k? it somewhat matches with the recent limited series - slightly slower than super-fast aperture. and it's well-regarded enough that the optics might justify the * designation along with sdm and weather-sealing. if used manual focus k-mount versions go for near $400 how much would the da*30 reissue be?