I use the 200 1.8 and it is awesome, and just the right reach for movement on the far side of the ring shots. It is also just the right reach for horses on the other side of an arena. The 1.8 though does well with movement indoors but I do get more blur than I like sometimes. I keep wishing it was a little faster. This lens isn't cheap but if you'd like to see how a 1.8 does with movement, there are several shots on my site at www.murryphotography.com. Just go to events and click on any of the dog shows. I wouldn't go any slower than 1.8 if you can.