> What are those sources? What are the testing methodologies? Where > are the charts and specifications of the tests? ...
Compiled from photographic publications such as Popular Photography etc. I would imagine they probably included Photodo MTF tests on earlier equipment. Cross-referenced the scores seem pretty reliable, as an example Popular Photography tested the Tamron 28-75 f/2.8 XR Di and found it to be comparable in performance to the Canon L series glass: http://www.popphoto.com/article.asp?section_id=2&article_id=711 http://www.popphoto.com/article.asp?section_id=2&article_id=663 In the listings on Photozone the Tamron scores very close to the top wide to standard zooms (Canon L): http://www.photozone.de/2Equipment/easytxt.htm#Zstf Yes it would be better to have the lens test in front of you with the test information etc. but MTF testing seems to be reasonably standardised across the photographic industry these days. John
