While the best equipment depends on the sport you are shooting, in general we are talking about long lenses and fast burst rates. I am typically shooting football which presents several challenges and represents perhaps the most difficult situation: long fields and night matches.
Lenses
Since I shoot from the stands I prefer to bring an unassuming lens. I would like to bring my 70-200m f/2.8L to provide more flexibility, but carrying in a large white lens can attract too much attention. The policy at each stadium/arena is different and I thus far have not had any problems in bringing in my equipment, but would prefer to avoid any problems. I therefore typically use my 200mm f/2.8L prime lens which is very sharp and fast. This lens runs around $650 which is not a bad price for a "L" lens such as this. The 2.8 aperture allows for a bit more light allowing for faster shutter speeds. Although 200mm is not exceptionally long, with a APS-C sensor and/or a high megapixel camera, a lot can be done assuming you are close to the field.
Camera Body
Since I am not a professional sports photographer, my kit is not really optimised for sports photography, but use what I have. My primary camera is a Canon 5D Mark II which, despite its low burst rate provides some advantages over other alternatives. It has excellent low noise performance allowing me to use higher ISOs, and being 21 megapixels provides me with cropping possibilities. If I would purchase another body now, it would almost certainly be the new Canon 7D which is close to ideal for this type of photography. It has an APS-C sensor, providing a 1,6x multiplication factor to the lens focal length. My 200mm lens would become equivalent to a 320mm lens. It has an 18 megapixel sensor given additional flexibility for cropping and noise reduction and an 8 frames per second burst rate compared to the 5D Mark II's 3.9 frames per second. It also has a 19 point auto focus system to help with fast moving subjects.
In my opinion, the most important characteristics for the equipment to bring to such an event are the following:
- Long, fast lens, at least 200mm and f/2.8 or faster.
- Camera with good high-ISO noise performance
- Lots of megapixels for noise reduction processing and cropping
- Fast continuous shooting
Some of these characteristics are not 100% necessary in all cases depending on the lighting availability, proximity to the action and size of the playing field.