The Topcor RE 20mm 1:4 is an early, slow and rather small superwide for the Topcon series of SLRs. Its optical construction is pretty simply, consisting of eight lenses in six groups. Only the Olympus 3.5/21mm has an even simpler [7/6] layout.

As with most RE Topcors, the lns barrel is well made, and it looks surprisingly modern. Focusing is extraordinarily smooth - comparable to contemporary Leica R or Minolta MC glass.

The performance of the RE Topcor 4/20mm is surprisingly good as well. Detail resolution is quite good even at f4, and even in the corners. Wide open, the contrast is rather low of course, but stoppping down - as usual with vintage superwides - increases both details resolution as well as contrast to pretty good values. Vignetting is apparent at f4, but gradually diminishes when stopping down. At f11 it's almost gone. Distortion however is pretty strong and - if you shoot architecture - due to its complex structure also quite cumbersome (see image further down).

 

Topcor RE 20mm f4 Topcor RE 20mm f4 pic
 		 TOPCOON TOPCOR RE 20mm 1:4               
(8 Linsen / 6 Glieder)

 

 

* Eine der gesuchtesten Konica AR-Linsen

 

 

Topcor 20mm f4 full image 

 

artaphot Topcor RE 20mm f4 corners

 

 

artaphot DSC00777

Above: The Topcor RE 4/21mm has some pretty strong and complex distortion which is quite bothersome when shooting architecture.
Image taken at the Rittersaal of the episcopal castle of Chur / Switzerland