Welcome to the Hood
In common parlance, "the hood" refers to whatever section of town you live in and feel at home. It's an abbreviated term for the neighborhood. In my hood today, I'd like to talk a bit about the importance of lens hoods. Because neighbors want to be helpful when they can. Welcome to the lens hood neighborhood.
I'm a big fan of using lens hoods. Using one may seem like a hassle initially, but it can quickly become a habit if you let it. And there are plenty of reasons you might want to make it one of yours.
People sometimes figure they don't need a lens hood unless they're shooting into the sun. If the sun is way out of the frame, you won't likely suffer from lens flare. But that's not the only source of light. Look around you right now. No matter where you may be reading this, you can see your surroundings only because they either emit light as the sun does or reflect it. When light falls on an object, it absorbs specific wavelengths and reflects others. The combination of wavelengths it reflects determines the color we see when we look at that object.
That object isn't beaming its particular shade of light only into our eyes and cameras. It's sending it out every which way to become what we call "ambient light." Some of that light will surely fall on the front element of your lens, decreasing contrast by muddying the waters. Yore camera doesn't discriminate. It records whatever light enters the lens during the exposure. A lens hood blocks stray light from hitting your lens' front element. It, too, doesn't discriminate. If the sun is nearby, a hood can help shield your lens. But the ever-present ambient light will be, too. Sunny skies or completely overcast, it doesn't matter. Ambient light surrounds us. The more of it you can keep off your lens, the better.
A lens hood can also help protect your lens in case of a fall. I keep a lens cap on top of every lens I own. It comes off when I'm shooting, but when I am, it's fitted with the proper hood for that lens model. Lenses are notoriously front-heavy. The odds are it will land face down if you drop it. Some people advocate "protective" filters, but I prefer protective hoods. A thin pane of filter glass can absorb minimal impact energy, but it will do a fantastic job holding fingerprints and smudges.
Lens hoods also help to keep smudges off your lenses. Since they extend outward, you will be less likely to touch the glass face of the lens accidentally. Demon-possessed tree branches have an additional barrier in their way, too. You have to watch out for branches, sometimes. You won't always realize this until too late. Eventually, it will hit you like a tree branch slapping you in the face, but it has a way of making its point. Still better in my book than getting tree sap on your lens glass. Lens hoods help in all sorts of ways, you see.
I'm sometimes asked about the odd shape of many lens hoods these days. It seems that only generic hoods maintain the full cylindrical shape now. But it's not that they're "cutting corners" to save a few bucks. Computers allow them to optimize the contours, extending further where the rectangle of the frame is cropping anyway, pulling back in the corners where that frame spans the entire image circle. Nobody likes vignetting, so you can believe lens makers have spent a lot of money on perfecting that shape for that lens.
I prefer to use OEM-specified hoods over attempts to invest in generic third-party hoods that claim to cover several lenses. Varying focal lengths make the design of hoods for zoom lenses even more complicated. But there have been third-party hoods produced for Nikon's "big glass." People who put down that kind of money for a lens are often willing to support niche companies that have "out-engineered" the original and built a better mousetrap. Or lens hood, for that matter.
You can often reverse bayonet-mounted filters for storage, mounting them such that their flare extends back over the lens rather than outward from the front — anything to save a bit of space in the bag so you can squeeze in even more. Over the years, I've also found that some can be stacked or nested to save room.
I like it when new lenses come with the proper filter included. Other times, it's mentioned only in passing that you can purchase one separately as an optional accessory. I suppose this keeps the list price for a new lens down, but since I'm going to buy the hood anyway, it strikes me more as a nuisance than a benefit.
I own a fisheye lens that doesn't support the use of filters. But I suppose it's earned the right not to, what with seeing wider than 180 degrees field of view and all. It's hard to keep the sun out of the frame when shooting with a fisheye. But then, it's also hard to keep my feet out of the frame with one. I positioned the camera where a tree was conveniently blocking the sun one time. Sometimes, you have to use what you have on hand to solve a problem.
You could say that lenses feel at home in a lens hood. I'm hoping that I've convinced you of the importance of lens hoods and that you are on your way to developing the lens hood habit. With a bit of practice, you'll soon feel at home in the hood.
Howdy neighbor. Welcome to the hood.