^It made sense for James Doohan to do his own closeups in that shot, as they didn't have to bring in the hand actor afterward and reblock it for his hands. Look how he's holding the device. As had been done so many times before, he held it so it blocked the view of his hand, ostensibly hiding his missing digit, rather than so it looked like he could use it properly. Probably the worst such shot is in The Enemy Within, when he's calling the captain to inform him of a new problem with the transporter. He holds his communicator in such an awkward position, you realize the thing has to have an omni-directional microphone.
