Ebon has a limited range where he can affect objects initially, but he can extend them out of his range when he concentrates solely on them. That's why he had to drop the first two R-Types because they were well out of his effective range. If, say for example, someone came up to him right now while he's searching the bottom of the lake his concentration would break instantly and he'd lose two R-Types. Further ranges makes it even harder for him to focus, but potentially assuming nothing is disturbing him he can go quite a bit. It's why Scout is his secondary class type.

Effective range of his Telepathy and Telekinesis: 50ft away from him. Furthest away on a sole object with absolute focus: One mile.