Here's a quick lesson in microadjustment:
1. Mount lens and camera on a stable tripod at a reasonable shooting distance from your subject (Canon suggests 50x FL). Camera should be in One Shot mode, center point ONLY and, for ease, turn on the AF Beep confirmation.
2. Activate LiveView and focus on a high contrast, well lit subject.
3. Once focus is achieved, turn AF off on the lens. DO NOT MOVE THE AF RING OR TRIPOD - IF YOU DO START OVER.
4. Go into your AF Adjustment menu under the AF menu on the 7D2 (last page I believe).
5. Once inside, you'll have a bar with 20 positive and 20 negative markings. You will move down the (-) side until you do not get an instant beep and then repeat for the (+). You now have a range of numbers where the camera shows that LV and VF AF matches. Divide the number in half and either add to the negative or subtract from the positive. This is you adjustment for that lens at that FL. If you are using a prime, you are done - go test and see if you are happy. If you are using a zoom, you must now start over and do the wide or telephoto end (the 7d2 allows for wide and tele adjustments and then adjusts the middle ranges based on the adjustment range). Remember to recalculate the 50X distance.
6. Complete this process for each lens and each lens/TC combo you use on the camera. Some lens may require no adjustment, some a lot, some on the tele end, some on the wide end.
It sounds complicated, but once you do it a time or 2, it's pretty easy. For best results, do it outside with sunlight on your target.