First and certainly not the last post covering the mechanics of this exercise staple. The Chin-Up can be loaded in many ways and different positions. From bodyweight cluster sets to heavy straight sets - you can be very creative in how you choose to accumulate fatigue with this movement.
Today I want to cover the range of motion (ROM) specifics of the chin-up. In the video I only pull myself up to eye level to minimize elbow flexion at the top. If you take a look at somebody performing a "full ROM" chin-up that includes touching the bar to the chest, you'll notice the last 1/3 of the movement has very little to do with shoulder extension (pushing your elbows back). At that joint angle the biceps is most efficient and in a prime position to do the bulk of the work. Additionally leaning back slightly will keep the biceps even more out of it.
Since I assume you want to build huge lats with your chins, we want to keep the biceps mostly out of it. The lifter that knows how to manipulate ROM will be able to load the target muscle more efficiently and keep joints healthy. Tension should not end up anywhere - we want to place it exactly where we want it to be highest.
Pulling all the way up so your chin is above the bar is worn like a badge of honor - similar to an ass to grass squat. Training for hypertrophy is not a competition.