You are adressing the old Nikkor Q 135/3,5 or later versions? (or maybe both if it does not matter)
The one I tested is the AiS version.
I also later checked Richard Haw's site
https://richardhaw.com/lens-repair-articles/ - apparently, the old Q has another optical design. Interestingly, Richard has posted no less than seven articles on different versions of the 135 f/3,5 (what a wealth of good information on his site!)
Another note: Richard Haw mentions a lot of flare on the older New-Nikkor 135 f/3,5 whereas I see very little of that on my AiS version. I suppose the coatings have been improved.
Still, of course, no comparison of any reasonable kind to the new
PLENA. I only wanted to make a reference to the two aspects mentioned in earlier comments, about a relative lack of vignetting and round bokeh balls in the periphery.
Although I find the 135 f/3,5 a very well-behaved little lens, even wide open, it is of course nothing compared to the hugely impressive PLENA. Images from this one are something of the most mind-blowing I have seen (also, it has 4 times as many lens elements)
Another thing, and this is a very simple thought, maybe too simplified, regarding bokeh and cat's eye effects:
I believe there may be a relatively simple relationship between these effects and a small diameter of the front lens elements and the max. f-stop. Not a direct, linear relationship, but a co-variation that can perhaps be used as a guidance. Meaning, 52mm filter thread which is obviously restrictive for a lens like the 50mm f/1,2 may in fact be plenty big enough for other lenses with small f-stops like the 105 f/4 Micro or this 135 f/3,5.
Anyway, this was the reason I decided to check the 135 f/3,5. The new PLENA apparently has an 82mm filter diameter and I am sure that is an essential part of its magic.
