What is a lens you can use with your camera for any situation?

Answer 1

The most versatile lens you can use is going to be a zoom. 24-105 mm is a good example. It covers 90% of the applications. Longer focal length would be for sport or wildlife photography. If it is not what you want to do, 24-105 mm is the lense.

Answer 2

a 35mm f/1.4 or 50mm f/1.4 lens is a good choice for most photography applications.