@Karjon - Welcome to the forum! So, here's my attempt at explaining the Shutter/AE lock options with the SL1...
1) AE lock/AF - Normally when you half press the shutter, the camera will lock the exposure and focus. With this option enabled, you can separate the exposure from the focus. So for example, lets say you want the sky to be properly exposed, but want to focus on some flowers in front of you. You would point the camera towards the sky, half press the shutter button to lock the exposure. Then you would aim the camera towards the flowers and press the * button to focus.
2) AF/AF lock, no AE lock - With this option enabled you can pause continuous focus. So for example, let's say you had AI Servo (continuous focus) enabled and you're shooting along the sideline of a soccer game. If some people walk in front of you, the continuous focus would focus on them since they are the closest subject. To prevent that from happening, you could press the * button and it would momentarily pause the continuous auto focus.
3) AE/AF, no AE lock - This is very similar to #2, except instead of pausing continuous focus momentarily, it actually stops it completely.
Comments
1) AE lock/AF - Normally when you half press the shutter, the camera will lock the exposure and focus. With this option enabled, you can separate the exposure from the focus. So for example, lets say you want the sky to be properly exposed, but want to focus on some flowers in front of you. You would point the camera towards the sky, half press the shutter button to lock the exposure. Then you would aim the camera towards the flowers and press the * button to focus.
2) AF/AF lock, no AE lock - With this option enabled you can pause continuous focus. So for example, let's say you had AI Servo (continuous focus) enabled and you're shooting along the sideline of a soccer game. If some people walk in front of you, the continuous focus would focus on them since they are the closest subject. To prevent that from happening, you could press the * button and it would momentarily pause the continuous auto focus.
3) AE/AF, no AE lock - This is very similar to #2, except instead of pausing continuous focus momentarily, it actually stops it completely.
Hopefully that all makes sense. Happy shooting!