Repeat after me: “Bright Pixels Are Sharp Pixels” (Willems’s Dictum).

And that is one reason Shiva is sharp here (see original size to really tell):

A major additional reason, which is touched upon in this article also, is the use of the flash: a flash gives us great light and high contrast; and it fires at 1/1000 sec at full power, so at quarter power, which is what my flash was set to, it takes just 1/4000 sec to light up the subject. That leaves little room for motion.

So I used a flash on a light stand:

As you see I bounced the flash off the wall. Flash fired via Pocketwizards, set to manual at 1/4 power, which on the camera needed f/4 at 1/250 sec, ISO 400 to light Shiva the cat properly. I used no light meter; just trial and error.

And that, as they say, is that.