Originally posted by emalvick I do find it a bit odd that all the WR lenses are generally zoom lenses while most of the primes are not WR. Is a prime inherently better in rainy situations anyway because it doesn't zoom?
Prime shooting generally requires occasional lens changes, which are impossible in the rain. That alone makes primes (WR or not) less suitable for rain work.
That said, Pentax offers 5 WR primes: 55, 100, 200, 300, 560. If you need a long prime, you're not likely just walking about but trying to shoot something specific, in which case you'll stay with the long prime for the whole rainy outing.
Another reason could be that Pentax strives for compactness in the primes. WR works against that.
Regards,
--Anders.