For the past few weeks I've become pretty disappointed with the Canon 5D's AF performance, particularly with subjects on the move. Yes, I know it's not a body that's geared towards that type of photography but because that's the type of photography I need to deal with (chasing a toddler around should be made an Olympic sport), the shortcomings of the AF system is painfully evident. Performance of the outer focus points become inconsistent in decreasing light, the AI Focus mode takes too long to realize that the subject is moving, and while there's the option to turn on those extra tracking points around the center focus point to help with AI Servo tracking, that doesn't help when you focus using the outer points most of the time.
So while I (and I suspect a fairly large contingent of other Canon owners) sit around waiting for Canon to announce the specs for the 5D's successor, I figured I'd test the waters in the opposing camp again. To that end I got rid of my Canon zooms (only had 2 to begin with, although it was tough giving up that 70-200 f/4 IS) and a couple of other knick-knacks and I picked up the Nikon D700 and a Nikkor 24-70mm f/2.8G lens. The main attraction of the D700 to me (besides the FX sensor) is the pro-level AF system in a non-pro sized body. I'm eager to test it out to see how well it does tracking down a boy in flight and in low light conditions.
Preliminary usage over this past weekend proved favorable and I'll probably post a few samples later on when I have time to process them. The 24-70mm lens is quite nice and paired to the D700 makes for a pretty excellent, if somewhat heavy, combo. Unfortunately my Canon 24-70 f/2.8 sold quicker than I expected so I'm not able to do a comparison between the two but I'll be testing sharpness against the Canon 35mm f/1.4. We'll see if this Nikon zoom is really as prime-worthy as Nikonians always like to tout. Also have a Nikkor 50mm f/1.4D lens coming in tomorrow which means I'll get to see first-hand how little light I can get away with while using a fast prime on this high ISO machine. That should be pretty exciting. =)
As far as ISO performance is concerned, from the little I've seen so far, I think I'm comfortable with the D700 up to ISO 3200 without much of an issue. ISO 6400 has to be pretty correctly exposed to do well. On the 5D I didn't think about anything up to ISO 800. ISO 1600 usually was ok but could look really nasty if exposure wasn't correct. ISO past 6400 won't be something I use often on the D700 though. Unless the exposure is perfect and all other stars are in alignment, there's not much use for 8000+ unless you shrink them down for web use or something.
But so far the D700 is really an excellent, excellent camera. It's going to take me awhile to figure out every aspect of it though which probably won't happen unless I decide to keep it. But in the meantime I'm looking forward to see how it fares against the 5D.
