----- Original Message ----- From: "Bob Talbot" : Whatever the tests say, you are right, try them for yourself. : I have and was forced to admit (painful on the old pocket!) that Sigma : was a false economy for me. The qulity does not match the real thing. I saw a shining example of this when a student handed me a photo taken late at night on a lonely road, sunset in the background, the road ahead illuminated by headlights and white lines leading off into the distance.. Now Sigma have long held a reputation for flaring, yet I've found few people understand flare, which is the result of light relececting from the lens elements lowering the contrast and overall image sharpness. Sometimes this is image forming light (the angle of the frame viewed by the format of the film/sensor) while other times it is the non image forming light - light that enters the lens from an oblique angle that does not contribute to the image (easily lowered by using the appropriate lens hood), at the extreme it's that row of diaphragm images one sees when a specular light source is included in the frame. The shot I was shown was causing the student a great deal of confusion as the lens was a current pro series fixed aperture Sigma, everything looked fine except that the white lines down the middle of the road were also present *in the sky!*. Yup, the lens had flared to the point that the internal reflections didn't just add additional light to the image area, but they added image! I suggested he try replicating the shot again with other non-sigma lenses which he did, duplicating the scene he shot it again this time with the sigma and his only other lens, a canon. The sigma again showed white lines in the sky - the canon did not. I have a Sigma myself which I like though I *really* have to think about lens hood use and controlling the flare to get anything good out of it. k
