What do you call the item that fastens into the bottom of a lens?

[kevinkt]

The thing that protects the side of the lens that would go into the camera.

Also what's the cap called that you place over your camera if you take the lens out?

And where can I get a replacement for those?

 

[Derrel]

Rear lens cap.

 

[tirediron]

Rear lens cap or lens rear cap and body cap respectively. From you camera/lens maker, almost any camera store, or on-line, either as OEM, or third-party.

 

[ceejtank]

Lens cap.. & Lens rear cap.

Amazon sells them. Need to know your lens size (52mm, 58 mm etc) for the front lens cap.

 

[480sparky43 43]

Rear lens cap?

Buy em anywhere you buy camera schtuff.

 

[KmH]

The thing that protects the side of the lens that would go into the camera.

Also what's the cap called that you place over your camera if you take the lens out?

And where can I get a replacement for those?

For what brand of camera?

For Nikon & Canon replacement parts like that look at BocaPhoto.com - We specialize in photographic accessories