Originally posted by NaClH2O How about a small K, M or even an A prime, even less to go wrong than the 43ltd. And a wide rubber band around the base of the lens at the lens/body junction.
I don't think there is that much to go wrong with a FA43 to be honest. There is no active or high current circuitry in the FA43 - a non SDM prime only needs to report 2 (maybe 3 things): aperture, lens ID, and maybe current focus distance (for the EXIF).
That can be implemented using basically a pair of potentiometers (and a set of pull down resistors for the lens ID), but these days for manufacturing economy the lens ID is probably in an IC (which is also fairly tolerant of water).
I'm moderately confident (though I am absolutely NOT recommending that you try it) if water is poured over the lens/body junction it won't get in - the seal, though not waterproof, is fairly tight.
As for water going in via the focusing barrel - again doubt it - it's not waterproof but there is some protection against moisture and dust.
You'll notice that Pentax has only released WR primes on SDM lenses - that's because you don't want a high current short so some extra protection is required. Not sure if the weather sealing adds to the size, it's more likely the SDM mechanism.
I can't offer proof, but I am reasonably convinced (based on the article I read a few years ago) that the Pentax designers don't believe their primes will have an issue in the rain coupled with a WR camera - that's why they have yet to release a single non-SDM WR prime 4 years after the introduction of the K10D.
[Edit: okay, I think we have the DFA 100mm macro WR which I don't think has SDM - but that lens is so big it's probably a good idea to improve the sealing]
I agree that for marketing purposes maybe Pentax should perhaps re-release some of their primes with perhaps additional sealing, or maybe just sell them as is but add a WR sticker, and that may satisfy those who need to see the letters imprinted on the lens with accompanying manufacturer guarantee.
But I wouldn't buy them.