Jeffery, I'm a photo tech geek. I got into photography because it allowed me to be a gearhead. So I'm well aware of all of the parameters of lenses, etc. I has the SK 150 2.8 non LS lens. Love that thing. But when I need to nail focus on the eye, I can't do it if for instance bangs of hair are near. Even if I don't recompose, the focus circle is so big you just don't know where the camera is going to grab. SO here you have this beautiful lens and back capable of capturing an awesome image, but the focus system won't let you do it reliably. So I end up capturing 10 images hoping that one will nail it.