Today’s Question: I see some photographers use a lens hood all the time, others only when in strong sun, still others (like me) never. Should I be using a lens hood all the time? Does it alter exposure, make metering more accurate, or offer some other advantage?
Tim’s Quick Answer: The key purpose of a lens hood is to prevent lens flare. Thus, in concept you only need to use a lens hood when the sun position is “in front” of a line formed by the front element of your lens. If the sun is “behind” the front of the lens, the lens itself will provide shade to prevent lens flare. Thus, it is a good idea to always use a lens hood.
More Detail: There are a few points to keep in mind when it comes to lens hoods. As noted above, a lens hood is only truly necessary when the sun is “in front” of the lens. But in reality it is important to keep in mind that you are likely to change your viewing angle from time to time when photographing. In other words, just because the sun is behind you initially, that doesn’t mean it will remain in that position for every photo you capture.
Also, it is important to realize that the “funny” shape of many lens hoods is very much intentional. Each lens hood is designed for the specific lens it is intended to be used with in terms of preventing lens flare without creating vignetting or other artifacts. Therefore, you should always be sure to use a lens hood specifically designed for the lens you are using.
In addition, while a lens hood is really intended primarily to prevent lens flare, it is worth noting that keeping the lens hood on the front of the lens can actually help protect that lens. If you bump a lens into a wall, for example, it is generally preferred to have the lens hood hit the wall rather than the front lens element.
As a bonus, having a lens hood attached to the front of the lens makes you look like a more intelligent and professional photographer. Just make sure you have the hood attached in the “hood” position, rather than in the inverted stowed position that should only be used when you put the lens back in your camera bag.