I have a Canon 550D camera with 18-55mm kit lens and a Canon 50mm f/1.8 STM prime lens. I am looking for differences between the Canon 50mm f/1.8 STM and the Tokina 11-16mm f/2.8 wide angle lens, specifically for concert photography (both evening and night time).
A Canon 50mm f/1.8 prime lens is quite decent for taking portraits from close proximity. The Tokina 11-16mm f/2.8 is a wide-angle lens and would give you significant results when taking the picture of the concert hall from a distance.
Both lenses have their own pros for concert photography. The 50mm f/1.8 has the added advantage of taking good quality images in low-light conditions. The 11-16mm f/2.8 would be preferable when you are looking to capture the whole concert scene in its entirety. It is also great for capturing audiences. Hope that answers your question!
Both lenses are better for concert photography. It just depends on what type of concert it is, what the lighting conditions are, what your position is in relation to the performers, and most importantly, what you want the shot to look like.
There is a huge difference between a mid-day performance at an outdoor festival, an arena event with full theatrical lighting, and an intimate set at a dark smokey club. Not to mention Symphony Hall. Your lens selection(s) will also be governed by your access to different positions in relation to the performers.
For more regarding how different lenses look when used to capture concerts, please see the examples at:
Keep in mind that on your APS-C 550D a 50mm lens will give the same angle of view as an 80mm lens on a full frame camera. Likewise, the 11-16mm lens will give the same angle of view as an 18-25mm lens on FF. Also remember that with a smaller APS-C sensor the lens' maximum aperture is even more important due to disadvantage of a cropped sensor when shooting in low light.