Um, hm... First of all, I'm don't think "collection" is really the term you're looking for here. I think what you're really wanting to know is how to keep your horse at a nice controlled pace so you can jump the jump? Collection is a completely different matter altogether and at the level you are, you really won't be in a situation where you need to "collect" the canter to a jump. You need to allow your horse to go forward out of a corner and take you to the jump, without dragging you, without being heavy on it's front end. The way you do that is to get it right on the flat so he already knows how to do it when you stick a jump in front of him. What so so so many people don't seem to realize is that a horse needs to go at a specific pace to feel comfortable to a jump. If you get him TOO slow, it's uncomfortable to the horse and you teach them to take off. Very rarely is slowing down in the corner the way to fix a horse that takes off. My gut instinct in this situation is really not as much a training issue on the horse, but the way you rode him to the fence. A horse that rushes to the fence and takes off way too early is rider error, usually caused by anxiety. (and you're not necessarily the culprit here. If he's ridden this way by lots of people he's going to be this way for almost anyone who gets on him) If you panicked and threw yourself at him, I'm going to assume that there was anxiety in your ride to the fence he was picking up on: clenching, digging with your seat, digging with your heels, stiffness in your arms, not being in balance with him, any kind of fear from you, all of the above. My advice is to learn to be solid to a jump on a horse that won't be triggered by your mistakes first, and then switch back to him.