Originally posted by pimpim I am doubting between the SMC and HD version of this for use on APS-C. Used from private sellers the SMC is about half the price (€250) of a brand new HD, €500. I am not expecting to be using this lens heavily, what is everyone's thoughts on this, will the lack of sharpness of the SMC be a disappointment or is it still fun enough to work with, also on the higher megapixel count K70 for example?
I have owned the smc version since May 2016 and used it extensively on the 24 MP sensor of my K-3. Shot at its sweet spot and processed with a good RAW converter that has a correction module for it (DxO PhotoLab, for instance), the smc DA 11-17 fisheye zoom remains a very satisfying lens, both in use and results-wise. I doubt the HD version would be significantly sharper, although the better coatings will improve flare resistance and mitigate ghosting. But even the older smc coatings are already doing such a good job in those regards that I've never been shy of including the sun or other pointed light sources in the frame or about shooting backlit scenes. By the way, the smc version was the first Pentax lens featuring the protective SP coating on the front element.
As long as you accept the inherent limitations of this kind of lens and don't expect standard or macro lens corner-to-corner sharpness, you should be happy with either version of the fisheye. Find yourself a mint copy of the smc, and if you're anything like me, you may well have a blast with it, without breaking the bank.