also, is it tough to manual focus on the d7000?
No. Use Live view, zoom the view screen in a few notches, and you can get a highly critical view at any aperture.
do I need a Katzeye?
is the optibrite extra worth paying for?
No. Live View is a better approach.
(1) A Katzeye's split prism is only in the frame center. If you focus in the center and then recompose with either of the Zeiss lenses you're considering, you'll move the focus plane and the image won't be sharp where you want it to be. With Live view, you can focus anywhere in the frame.
(2) A Katzeye needs to be installed, which can screw up focus / viewfinder perspective alignment for all of your lenses.
(3) A Katzeye won't help you with the classic Zeiss focus shift, meaning you'll be shooting wide open or at f/8. Anywhere in between and focus shift will screw you up. (More on this, below.)
sorry to pepper with questions
but i see zeiss photos and I want to learn how to do that
I'm thrilled with my 17-55 nikkor
so I think the zeiss 85 or 100 is just what I'm looking for
Maybe. Two important things to know about Nikon-mount Zeiss lenses:
(1) They aren't really Zeiss lenses. They're Zeiss-branded designs manufactured under contract by Cosina. Cosina isn't known for exceptionally high-quality products.
(2) The Zeiss 85 planar design exhibits significant aperture focus shift, meaning that the focal plane moves back and forth as you change the lens's aperture. If you're focusing with the viewfinder, this is a big problem. Regardless of your aperture setting, as you look through the viewfinder, you're seeing the lens wide-open; the camera stops the lens to your setting when you actually shoot. This means that whatever focus you hit through the viewfinder will move when you hit the shutter and the camera stops the lens down to your selected aperture. By f/5.6 - f/8, you'll have enough depth of field to cover the shift, but anywhere between f/1.8 - f/4.5 or so, the shift will keep you from ever getting tack focus.
If you focus using live view, you can stop the lens down and actually
see the image at your aperture setting--thereby solving the problem.