I have been taking photos at the local speedway with a Nikon D50 and a Tamron 28-75 f2.8. I can get some decent shots in the daylight: The problem starts when it gets dark, and I end up at 1600 ISO. Not a good setup for my outfit. As you can see, I need a higher ISO, and a longer, faster focusing lens. I realize the WB error, and have corrected it by using custom WB. This photo is taken while the car is stopped, so I could use much less shutter speed. I was thinking of a D300 or D700, along with that Sigma 80-200 mm lens with the focusing motor. Another lens choice is the AF-S ?-200mm Nikon, although a $2k lens is probably not in the budget. This track uses those low pressure sodium lights that give off an orange tint, and the lighting is very uneven around the track. There is the fence and low hanging electric cable to contend with as well. This D50 otherwise does what I want, and I'm sure I would continue to use it in other situations. It is non productive in this tough light, though. I am looking for a camera that will serve me at least 10 years, and am leaning toward the D700, although the price difference of the 300 gets my attention. I would like to fool around with a D700, and maybe put a 50mm F1.4 on, and try some crops. Also, is the ISO performance of the D700 good enough that I could use a f4.0 lens in this light? Does anyone have any opinion, or other points to ponder before I make a decision?