version 1 was collapsible
2 was rigid/ DR, almost always satin chrome and has small tab /infinity lock.
3 was usually if not always black, no infinity lock & no tab
4 was black and early ones had no shade , later current have a slide out shade.
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None are bad handling. #2 has two slots in aperture ring for accessories
Just remembered there were two versions of #2, front element is distinctly different. A version was heavy chrome. B version was satin chrome.
As the line progressed , the center area of sharp definition at F 2.0 gets bigger until it cover the full frame on the APO. Finger tab returned on APO.
Around 4 or 5.6 all are fully sharp, but contrast gains are evident.
None are bad handling unless you demand finger tab.