Indoor Light Sucks
After 4 years of shooting grade school and middle school basketball, I've come to the conclusion that indoor gymnasium lighting sucks. You're either going to have blur, an odd color cast, or too short of a depth of field to capture all the action.
Lighting you are screwed on; they may have 1, 2 3 different color temperature bulbs over the ring. You just have to deal with it and see if it's even possible to color correct in post.
For focus, change to Center Point focus only - that will prevent the ropes (closest object) from stealing the focus. Aim the center cross hair at the center of the action. Press the shutter halfway down to lock focus on the subject, then recompose the picture and fire the shot.
You can also change the exposure metering to center weighted exposure (use the Q menu) so it will meter off of what you are focused in, instead of trying to get the whole scene to expose properly. All that dark around the ring you just don't care about and if it's underexposed, so what.
For blur, you're also screwed, indoor shots have notoriously bad lighting. Blur is a function of too long of a shutter opening, caused by poor lighting, too small of an aperture or to low of an ISO.
You can go with the largest aperture f/stop (TA on Canon) to let more light in for a shorter exposure, but that risks having some of the subject out of focus -- see Depth of Field vs aperture. Another option is to max out your ISO; the T6 does a fair job at ISO 6400, which just means the camera is amplifying the light a lot more, which does induce speckles and noise in the image.
If you will be doing a lot of indoor arena shots, you'll want to invest in a clean high-ISO body (Canon D80, 77d) and either a f/2.8 zoom lens or a 85-100mm f/2-f/2.8 prime lens, and use post production to zoom in / crop for best effect. Basketball can generally all be captured with 85 to 100mm of zoom on a crop-sensor camera. Other indoor sports, it depends on how close you can get to the action.
- Will England, Lensman