I get that people just refer to them as time machines, but they're actually space-time vehicles.
Before your first journey, you calibrate it to a reference point (mine already had Earth mapped out, with a gravity well depth monitor as a fail-safe) so that you lock your target coordinates in space and time.
But no, it's not teleportation. You're still just travelling to your destination, you just get there as quick as you want and without the need to be disintegrated.
Yeah, I have normal camera lenses lower than that. From memory, the F-stop number is like a ratio between the focal length and the effective diameter of the lens.
Poochie knows.