Camera Lens Parts: Lens Cap Ring
One of the most important SLR camera lens parts is the lens cap ring. This ring at the very front of the lens allows a lens cap to be mounted so that the lens is protected from scratches and minor collisions. There are two types of lens caps that can be used, but they are dependent on the lens ring.
Plastic Lens Caps
Plastic lens caps come standard with most lenses. These lens caps pop onto the lens cap ring. Usually, the lens cap ring is fixed onto the focus ring. The lens cap can be easily removed from the lens by gently applying pressure to two release buttons. The advantage to this kind of cap is that it can be quickly removed. The downside to it is that it can also easily be accidentally removed. It often just takes pressure on one release button for the lens to become loose, and that can happen from just a slight bump.
Metal Lens Caps
Larger and more expensive lenses employ metal caps that screw on to the outside of the lens cap ring. These lenses are much more secure than their plastic counterparts and can not be removed so easily. The downside to them is that they take longer to remove, which means that you could miss out on some action.