Yes, I was referring to the AF primes which always seem gigantic compared to the nice Pentax jewels. For IQ I was referring to the fast Sigma primes, those that go better than f/2.

Consensus is that the DA15 is "excellent" and the DA21 is "good" (I've not used either). I love my manual focus Vivitar 24/2 Close Focus but when it comes to wider than that I reach for the DA12-24. It's the only zoom I care to use, as it is simply impractical to carry primes in all those focal lengths -- there is enormous difference between 12mm, 15mm, 18mm, 24mm, etc. Even if there were primes for each of those focal lengths they would be no faster and have no better image quality than the zoom. (Even at the 24mm end I prefer to shoot the prime at f/4 for IQ reasons.)

The main benefit of something like the DA15 is of course size, with the compromise of not being wider. Then again the same argument is used by those who like the Sigma 10-20mm but I would not be as happy losing 24mm and the edge in IQ the Pentax provides.

I personally do not like Sigma primes as they are big and ugly. Though fast they do not have edge performance until you stop down a lot. That may be OK in a portrait lens but for wide angle I generally want everything sharp corner to corner.

Chris, if size is the thing go for the DA15. I can't see how you would be disappointed. It makes the most sense after the DA40 so you have a wider focal range covered.

I suppose it is the right lens for nits however, since there seems to be a good amount of nit-picking going around.

Not imposable nor even impossible! Merely the wrong tool for the job.

Yes, I was meaning magnification power outside the macro range. My sentence caused confusion by through concise. Sorry about that. Reworded:

As a macro lens, the focal length does not provide enough clearance for insects. Outside the macro range, it does not provide the same magnification power as lens in the 100mm range.

To go further, I'd note that the lens does not provide 1:1 magnification for many subjects since you'd have to get them inside the lens hood!

Your lens choices are all over the map! None of them are actual "alternatives" to either a 35mm prime or a macro. And if, as you say, you are getting the 18-135 anyway, put all thoughts of other zooms out of your mind (for now).

As for the DA35/2.8 Limited macro, be assured that it is a most excellent lens, essentially a replacement for the old 50mm macro on APS-C. It works as a crystal-clear landscape lens, a good street shooter, a general-purpose snapshot grabber and is the best flower lens I have used. It is almost impossible to take a shot in close-up that doesn't look fantastic.

A few provisos. The focal length does not provide enough clearance for insects, nor the same magnification power as a macro in the 100mm range. It is impossible to manual focus once out of the macro range, since the helicoid is maybe 90% devoted to close focusing. It is for that reason -- and the fact that I simply don't much like 35mm -- that I traded it away. But I would have kept it if I hadn't needed the money.

If you want a single do-everything prime, this is the lens to get. If you don't care so much for macro, save money and get the DA35/2.4 which I have not used but which looks very nice indeed.

The FA31 is almost 32mm, when measured, and thus acts more like a 35mm. If anything, something wider than 28mm would be the sweet spot, specifically 24-28mm.

(This has been thrashed to death in many threads, including Vivitar 28mm As FA31mm Replacement?)

No doubt you are correct. And the lens also focuses closer, an important fact not often mentioned. However I hold that for most typical applications of a wide angle, that is not as relevant. But either way it highlights how impossible it is to recommend specific lenses unless the use cases are clearly stated.

I am all for fast lenses but I agree that f/4 is perfectly fine for a super-wide. It's not as though you're going to be using it to get thin DOF, quite the opposite in fact. So the extra stop is not nearly so useful as it would be on a normal lens, for example.

I traded for a DA12-24 some time ago and have never regretted it. A great lens considering the compromises of wide angle in the first place.

Yeah, a lot of us have been wondering about that!