You asked
Pentax smc da 50 200mm f 4 5 6 ed wr vs pentax 18 250mm f 3 5 6 3?
The Pentax smc DA 50-200mm f/4-5.6 ED WR is the one I can describe in detail. It's a zoom for APS-C Pentax K bodies with autofocus, but no stabilisation. On APS-C it frames like 75-300mm on full frame, so it suits distant subjects and telephoto landscape detail.
The [Pentax smc DA 18-250mm f/3.5-6.3 ED AL [IF]](/gear/lenses/pentax-smc-da-18-250mm-f-3-5-6-3-ed-al-if/) covers wide to long telephoto in one zoom. I don't have its full specs on the site yet, so check its page before you buy.
If you want one lens for everything, the 18-250 is the convenience choice. If you mostly shoot at long range, the 50-200 is the one I can vouch for in detail. The travel picks explain why a single all-rounder often makes sense on the road.
Written by Claude from this site's pages.