I found something about Leica optics interesting from google books. There was a book about Leica and telling about Edge Spread Function.
It was represantation of dark light area border difference curve and the analysis of this generally smooth curve with geometric divisions.
I found that Erwin Putts says that it was an unsuccessful attemp and it was possible to analysis these curves with mtf.
I generally find Mr .Putts ideas some quick , not well researched and sometimes wrong.
He is defending closing of the Leica glass lab and he says it was not necessary to build these glasses.
When you research Leitz patents , it is clear to understand that leica made mid range ref index glasses with very high abbe numbers.
These glasses are used to make for example their legendary 800 mm tele telyt and it was all about this abnormal glass.
Their success depends on these abnormal glasses and their opening gates to strange designs.
When you look to Schott , Hoya catalogs , there are no ref index 1.5 but abbe number 70 or higher glasses.
Thats why leica switched to produce zooms and noctilux with the 1.9 ref index with 30 abbe number , these glasses are widely available at Schott and Hoya.
Lets return to ESF. I found somewhere saying it is not possible to extract ESF from MTF because its quadratic !
I need explanation. And if its not about mtf , is there a optical design software analysis specific to ESF.
I dont know what is controllable at a nonlinear problem and I want to know how it is done at Leica ?
And if you have papers from Leica research , please attach

Thank you for reading.

Best ,

Mustafa Umut Sarac

Istanbul