It looks like the focal plane was held constant. It’s actually the len’s “fault” that some of those are out of focus. At this scale it’s relatively easy to see the dependence on wavelength that causes axial/longitudinal chromatic aberration.
The Componon-S 50mm is only achromat corrected, so if you get your red or violet channel focused perfectly, green will be noticeably blurry if you don’t move the lens.
I measured this a couple years ago vs. the APO-Componon 45mm. Check out the green line in the graph about halfway through this post. The APO version of the lens essentially solves the problem… but at roughly 8x the price of the achromat. 
You can try to mitigate the problem a little by stopping down the aperture, but both of those lenses have a sweet spot and are sharpest at a particular F-stop, so it’s not a perfect solution.