As to converters, quality depends on the converter, how it is used, and most importantly , the lens to which it is attached -- and how it is used. Lots of people will trash any converter -- but there are lots of people that even trash the use of a UV filter, for Pete's Sake. Minolta, Nikon, Sony, Tokina and lots of other companies made great converters that they felt met their standards. You'll have to decide if they meet yours. I use various converters all the time, and I have no complaints -- but I use them carefully and correctly.