[cfranks (Charles)]

Hi,

I'm trying my Canon EF 70 - 200 f2.8L IS USM lens with my QSI683ws-8, using the QSI-EOS adapter. Wide open at 200mm produces a field curvature of 46%, a bit more than I need! Using an aperture mask of 28mm dia, the curvature drops to 22%. Has anyone used this combo and got better results? I'm not too knowledgeable here but could an incorrect back focus distance give this kind of problem?
Thanks
Charles