A fast 28mm lens gives scope to an event in that for example you can easily get the audience and the speaker in the same shot whereas often with a larger lens you can get one or the other but not both. Operating close with a 28mm means there is less chance of someone walking in front of you when you are about to take the shot. Apparent depth of field and sharpness are also good. Large group shots are also easier and demand less stepping back to take the shot.

A fast zoom that goes to 200mm, allows you to be unobtrusive when taking some shots. Centering in on an isolated activity involving a small group of people is also possible.