Optimizing enlarger lens; Meopta Belar 75/4,5

This enlarger lens with zebra body has square blade. I like this combination.
I'm trying to explore it these days. At first I planned to use it for macro photography, as my friend said that, enalrger lens is the best for macro. Yes it's has magnification. And soon I find out that it can be used as a portrait lens, but without focusing ring (this time). Focus is fixed now.
Equipment:
1. EoS 1000D Camera
2. Extension tube M42
3. empty black film tube, used as extension tube. For portrait I cut almost half this tube.
4. stereofoam and tape

M42 extension tube, I only use the thinnest one

Here's the result, no edit;

Panning my son

Original file RAW, saved in PS

, Square bokeh, Original file RAW, cropped in PS

Now I played with NEX5