on 13/1/02 6:49 pm, Daniel ROCHA at [EMAIL PROTECTED] wrote: > From: Bob Sull <[EMAIL PROTECTED]> >> Hmmmm, could this be indicative of quality control problems? Two samples > with >> two different results? > > I can't say... But with the DG Sigma Series, we must take care... > > DG clearly indicate a lens adapted for digital SLR, with the multiplicator > factor. > Therefore the edge... In my opinion it's not realistic to search the same > quality in a DG lens than another one in the EX / HSM lenses from Sigma. > > For the moment all DG lenses are poor performer in the edge ! Some of them > are better than other but...
Interesting. What does poor mean in this case? Is the image soft, is there vignetting? AP's test takes two parts; a "real world" test (from where the quoted section came), and a test on the optical bench by Dr. Stuart Bell. Digging out Dr. Bell's chart for the 20mm shows that there is some barrel distortion (measured as about +0.2). Light fall off is measured as -1.4 stops. This is done with the lens wide open. (This last can be compared with a measurement of -1.7 for the EF 17-35mm). The test appeared in the 22nd September 2001 issue. * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
