Hi Glen.
There are at least 2 versions of the E43 and at least 1 earlier version that uses ser VII filters. All of these versions only focus to 1 meter and have detachable hoods. The earliest ones have 2-piece hoods that house the Ser VII filters while the later ones use an E43 filter. The last pre-asph version focuses to .7 meters, has a built-in sliding hood and uses E46 filters.
Now re performance characteristics. I am referring to the f4 and under range as by f5.6 they are all pretty much like any other 50mm M lens. The E43 is excellent, being very sharp centrally with a pleasant fall-off in resolution as you hit the corners at widest apertures. The older Ser VII is nice too, but notably lower contrast and not as crisp centrally as the newer ones, and shows a more classic "swirly" background bokeh when used wide open that can sometimes go "clumpy." The E46 model is very close to the E43 in rendering, but exhibits slightly less resolution fall-off towards the corners and slightly higher micro-contrast, but surprisingly may not be quite as sharp centrally wide open. Understand the differences I am describing between E43 and E46 here are very minor and you'd probably need to compare images side by side to quantify them. Both have very smooth bokeh and render quite similarly (IMO) to the 28 Cron.
At the end of the day, I would/could be quite happy with either E43 or E46. I probably have a slight preference for the E43 rendering, but a stronger preference for the E46's closer focus ability, so that is the version I currently use.
Hope this helps!
