Some people claim the Spot AF is the “holy grail” of the focusing on the Canon 7D. That’s because the area is so small, that you can decide were the focus will be. The spot AF is available on all the 19 points. Every point can be selected with the joystick.
When selecting the Spot AF, the display shows a small box inside the regular focus point. And that’s where my problems start with the Spot AF. According to comments from Canon, the actual area of the Spot AF sensor is larger than the inner box displayed. How much? Don’t know, but it must be smaller than the single AF point, so it’s somewhere in between.
The only time that I’ve used the Spot AF is for the micro-adjustment of my lenses.
- For getting focus on smaller areas and hopefully getting a more precise focus.
- For getting focus when the depth of field is extremely thin, like when close focusing with Canon 85mm at f/1.2.
- Because it’s a small area, it can’t always focus if the subject is not “appropriate”.
- The area of focus needs “contrast/details”.
- Extremely difficult to use in AI Servo mode. If you can track and keep the focus with the Spot AF, I will bow to you in admiration of your skills.
- The viewfinder doesn’t display the exact area used by the Spot AF.