Originally posted by kruser1947 It's no surprise that the prime lens is sharper, but that much?
The problem doesn't appear to be lack of sharpness but focus.
Your Sigma images are not focused on the needle but in front of it in the a/f image and behind it in the m/f image. In the a/f case 1) if the K-30 is focusing on the needle, then your K-30's a/f system needs microadjustment to calibrate it properly to the Sigma lens. BUT I suspect it's not focusing on the needle. 2) For the a/f tests it would be much better to stick the needle in a blank sheet of paper, because your K-30's a/f system will focus where it finds the most contrast, i.e. on the black/white borders of the squares. Having a blank sheet would guarantee that the a/f system would focus on the needle and not anywhere in front or behind.
In the m/f test case: it's operator focusing error.
Once you fix your focusing you'll be able to properly compare the sharpness of each lens.
In all three tests, the white squares have a blue cast on my screen, more so with the Sigma, as point out. But the whites appear a long way from being "whiter whites" IMO. Depending on the lighting, you would need to adjust the K-30's white balance. Here is the original Pentax-M image (on the left) side by side with a colour-cast-corrected copy.