falconbach wrote:
I have been thinking about buying Nikon 70-200 F/4 (I'm using AF-S 80-200) for my pet photography, how is the tracking performance? Also how is it in low light/contrast situations?
Stefan – Thank you! Venus looks like quite a character. Hard to think of snow today – we are enjoying a glorious (and probably record-breaking) 83F / 28C day.
I have found the 70-200/4 to have very good focus tracking for running dogs in good light (but see below). For slow-moving subjects, the 70-200/4 grabs focus well in low(ish) light, although perhaps not as well as an f/1.8 lens.
Caveat: I have never used a pro-type zoom such as the 70-200/2.8, so I cannot provide a comparison to that.
I did find one review that compares the 70-200/4 favorably with the 80-200/2.8D with regard to acquiring and tracking focus for sled dog racing. Link:
More info re your question: Red Dog is the most difficult challenge for any lens and autofocus system. Her short, low-contrast coat does not give the autofocus system much to work with. Also, Red Dog runs like a greyhound – she runs very fast, and in addition her head bobs up and down significantly with each stride. This often takes her head outside the focus area if I am shooting in landscape mode.
When Red Dog’s head leaves the focus area, the camera/lens grabs the highest-contrast point it can find, usually her collar or the white blaze on her chest. Consequently I have lots of pictures where her chest and collar are in perfect focus, and her head is slightly outside the focus area.
I consider this is operator error. If I get a chance this afternoon I will try some “running dog” pictures in portrait mode. That should help keep Red Dog’s bobbing head inside the focus area.
Thanks Bruce_T for the info. I would like to get some of that heat you have there, it is getting cold here in Iceland haha.. Venus loves the snow, specially when we have alot of it so she can bounce around like a kangaroo.
Bruce_T, Sammy is so beautiful. Like the red blanket.
rxgolf, yours are beautiful as well. Must be very still to get sharp image with 1/250 in shutter speed. At least that shutter speed don't work well for my girl for sharp photos.
Here's Venus looking for her ball in the winter sun.
Venus loves the snow, specially when we have alot of it so she can bounce around like a kangaroo. 
