Originally posted by kitkat
The DA 50-200mm F4-5.6 ED has AFAIK been around quite a while. There is now an smc DA 50-200mm f4-5.6 ED WR lens, which costs 50% more than the older lens.
Not sure where you are seeing the prices come out that much different, but you must be seeing an unusually cheap price on the original or an unusually expensive price on the new one. The original traditionally sold for somewhat over $200, which is right around what the new WR one costs. I suppose some dealers may now be dumping their old stock of the original for bargain prices, but the "regular" price is not that much less than the current prices of the WR version.
Anyhow, yes, John Carlson from Pentax has confirmed these are the optically identical. BTW, aside from weather sealng, the WR version also has a smaller filter size - 49mm instead of 52mm.