Ultron vs 45P
Got both finally and found the following:
1. 45p very good even wide open. Whole frame (DX) is clear but Ultron is only clear in the centre (and my copy is blurred in the bottom possibly having a misaligned element). when the periphery is not clear the transition is not nice. The 45p does not have this issue to start with because the whole frame is clear.
2. 45p is a tad blue and Ultron is very stable. You could call it a tad yellow but that's splitting hair.
3. 45p is better in critical sharpness and "fidelity"
4. 45p is good at all apertures. My copy of ultron is only good at F4 for people and F5.0~5.6 for scenery. Actually my copy has issues with the bottom part of the image (that's awful QC!!)
5. In situations where 45mm is too tight, that extra 5mm often gives you enough room for another attempt in terms of composition possibilities but it is not a drastic difference.
6. 45p has way better (more gradual and natural) transition from near to far. Ultron is way more abrupt and sometimes inexplicible (and looks like zooms smearing artifects). Often the 45p, dispite longer focal length, at the same aperture value and distance has better DOF than the Ultron and the transition of image quality with distance is way more natural.
7. Ultron has a very round aperture opening at most F stops and in general hokeh is more intense and better than the 45p. But the transition from near to far is quite unnatural for the Ultron. To me bokeh and transition of image degradation with distance do not directly equate, YMMV because the same words often mean different things to different people anyway.
8. 45p is way more low light capable. Overall all F stops, all distances is better. I refuse to bring just the ultron to a museum, for example.
I can personally tolerate owning both but will not be not carrying both.
As I always meter by eye I don't really want to test the auto metering. Just mechanically switched it on and it worked No overexposure but again I am not qualify to say anything on something I don't use.