pm63 & Overread:
Thanks for the comments, like I said the sun and shade were making life very difficult and I was having a hard time with the settings.
pm63 - the cheetahs were not moving out of that concrete culvert thus not giving me a real natural shot. Normally I would not have taken the shot but after standing there for about 1/2 hr and wanting a pic I took a few. I also agree with you about having a good background, I don't like a unnatural or man made background and normally wouldn't have taken the shot.
Overread - I will pay more attention to the F-Stop next time, thanks for explaining that. I don't like shooting a ISO higher than 400 on my XTI, never quite looks right. If and when I can afford a new body I will up grade. I also don't have a tripod or external flash (something else I need to purchase) and I also didn't know if my flash would work from that distance? I too am Leary about using it at the zoo?
The white tiger was shot completely in the shade and through a wire fence and from a good distance? I was playing hell trying not to get a reflection off the fence and make the fence disappear at the same time. Again I will try and slow down and pay attention to the F-stop and focus. The softness may have come from the shot or from all the work I had to do in Photo shop?
I'm finding that the 100-400 would probably be the better lens for what I like to photograph. Some day when I can afford it, I'll get one until then the 70-200 will have to do. I'm still new at all this and still trying to understand all there is to know about DSLR's and hopefully will start to get better.
Thanks again to both of you for you comments.
Ross