Originally posted by ychousa Do F50 and FA50 f2.8 share the same optics? It looks like FA 50 is cheaper. Do you think it's better than DA 50 macro for pentax K-3?
Not sure about F/FA optics but all of the Pentax macro lenses are good. Any differences are just nit picking. Get whichever one you find at good price.
You should determine what focal length you want though. 50mm is relatively short, I often use 100mm or even the DA*60-250 for product shots to get the correct view. Depends on how large the item is. And the purpose. For high end magazine or advertising get the best lens you can, for ebay the kit lens is already too good. Take your zoom lenses and snap some shots of the items, determine what focal length is best using the zoom then invest in the prime that works best for that.
Do you need macro? How close do you need to be to fill the frame? That is what you need to decide.