Different Versions of Collapsible Summicron

[Hern]

I've been searching all over this forum and the internet about the optical variations between the different serial numbers of the collapsible Summicron, and have come up dry aside from the distinction between the early radioactives and the somehow more desirable 13x serial number Summicrons. Does anyone have links or a more substantial write up about this?

 

[mcfingon]

Erwin Puts writes about Leica lens versions:
http://www.imx.nl/photo/leica/lenses/lenses/page92.html

 

[mcfingon]

You can legally download the text but not photos from his 2005 book Leica Compendium
http://www.furnfeather.net/books/pdf/llcforweb.pdf