Originally posted by Fraggle79 I'm having trouble understanding how this works with an APS-C camera such as K-3.
Originally posted by mee A 15mm FF lens is still 15mm on crop but the view is quite different when comparing formats..
I think by trying to explain all this to someone who has only ever shot on a crop camera we just confuse the heck out of them. Now I am assuming that the OP has only used APS-C based on his/her question. I could be wrong. Speaking for myself I can say I have really only experience with APS-C. My film experience was so long ago it really is forgotten. So for me, and anyone else who has only APS-C experience when everyone jumps in and tries to explain crop versus FF and the different angles of view it just really confuses people to no gain.
If all you ever shoot is APS-C forget about the crop factor, no matter whether you put a FF capable lens or a crop only lens on you will still see the same angle of view, nothing changes. Now if you are switching formats back and forth or if you are considering the K-1, or another FF digital then yes you need to understand the "crop factor" thingy.
So to answer the OPs question: How will this work on the K-3? Just like any other lens you have. Nothing changes just because this lens is capable of being used on a FF camera. Put the DFA 15-30 on your K-3, set it to 16mm and the angle of view will be identical to the DA*16-50 or the DA 16-85 @16mm.