A camera lens hood is a cylindrical plastic piece, rubber, or metal that fixs over your lens to prevent light from shining straight into it. The hood can screw onto the front of the lens or many hoods are linked to the lens and may slide out like a sleeve.

When I first got my DSLR camera I had no clue what a lens hood was. I purchased my camera used from a friend. It came with two lenses. One of the lenses had a hood. I never used the lens hood at first. Yes, I had a film SLR camera when I was younger and I should've known what a camera lens hood was, but I don't ever used one hood then either. One day I made a decision to use the hood to see if it made a variation and it did. Now I use my camera lens hood most often.

Hoods can come in a variety of shapes and lengths. They are usually cylindrical, but they can also be square. The edge of the hood could be straight or flowered. Flowering of the edge should aid prevent vignetting when the hood is on properly. Hoods are made for each type of lens. Be sure you use the hood that was designed to be used with your lens. If you use a different hood you could get troubles, like vignetting.

Digital Photography Fundamentals - Enhance Your Pictures

Lens hoods help reduce the shapes and streaks of color which bright light may cause in your photograph known as lens flare. But that's not the only thing a hood can do.

Using a lens can also help make the colors in your photos look richer. It helps stop you from getting blown out pictures.

If you desire to use flare as a creative effect in your picture you will not use a hood, certainly.

Digital Photography Fundamentals - Protect Your Lens

As the hood sticks out from the front of the lens the way it does it may aid protect your lens from damage. That's not the purpose of a hood, but it can act as additional protection to prevent things in contact with the glass at the front of the lens.

It can also help protect your lens from getting water or dust on the front element.

Digital Photography Basic principles - Possible Difficulties with Lens Hoods

Sometimes hoods may cause troubles with your pictures. If your hood is much too large it might block your camera's built-in flash. If that is happening you will notice that your photograph is darker at the bottom.

Often you may notice vignetting if you use a particular lens hood. This all depends upon the lens your using and the size of hood. Lenses with a wider field of view cannot use longer hoods. If you use a hood made for the particular lens your using, you wouldn't have this problem.