Please Do This 〜てください

てください is built on the exact same て-form you already use for connecting actions and for 〜ている, it’s not a separate conjugation to learn, just a new job for a shape you already know.

ないでください is built the same way, just on the verb’s plain negative stem instead of the plain て-form: 撮る becomes 撮らない (don’t take), then 撮らないでください (please don’t take). It’s the polite version of the plain-form ないで from Without Doing, dressed up as a request instead of a connector.