And an exception…
I believe that you should generally always use a lens hood on your camera.
1. It helps prevent the lens flare you can see. We all know that starburst effect you get when the sun is in the picture – that’s called lens flare. It’s usually (but not always) a bad thing.
2. It helps prevent the lens flare you cannot see. There’s a more prevalent type of lens flare you often don’t notice with your naked eye. It causes pictures to loose contrast due to light refraction.
3. It protects the lens from damage. I don’t believe in leaving a filter on my lens for protection. Instead, I rely on the lens hood. In 37 years of serious photography, I’ve never damaged a lens front element.
4. It protects the lens from the elements. When I was making this image it was snowing hard. Had I not had a lens hood, those flakes would have been landing directly on my lens element.
When you’re shooting macro – you might need to remove the lens hood to get close enough to your subject to get the shot in focus.
As to other exceptions people might raise like it’s too hard to turn the circular polarizer, etc. Those are simple problems to solve. Remove the lens hood, rotate the filter, re-install the hood.