Going from a K-50 to a K-S2? Not sure it's worth it as much as the leap to a K-70. Sure the K-70 would cost more, but the camera body new is ~650.00. I'd skipped over the K-S1 and K-S2 as it was a much less incremental upgrade over my K-50. The K-70 was a much larger incremental upgrade.
The benefits you'll see are:
* 24M sensor versus 20M sensor of K-S2
* Fantastic ISO range with very low noise (due to new companion "accelerator" chip partnered with Prime MII processor) See details on the new chip here
Features2 | PENTAX K-70 | RICOH IMAGING Prime MII was also in the K-S2, but the accelerator is new to the K-70. Comparison examples show the noise is lower even compared to the K3 II.
* Pixel Shift - I've taken portrait pictures with this feature and had it work so if the subject is slow enough it works for more than just "landscape".
* AF-C in Video (not that it's much of an improvement but the ability to continuously focus in video is a step up over any other Pentax).
* Hybrid AF in Liveview and Video. Still has Pentax limitations compared to some, but it's a marked improvement over the K-50, far less hunting for focus in LV.
* Slightly more conservative body design (no orange plate).
If you save your self several hundred, it's one thing, but I do think those advancements are worth the pricing difference.
Last edited by SeaRefractor; 10-05-2016 at 12:37 PM.
Reason: Edited for clarity