I noticed that some photographers are using lenses with a hood or shade but one of lenses did not come with such an accessory and I lost the hood for my other lens. Is it really necessary? If so, why is it not included with every lens of every brand?
Yes, Viktor, a lens hood (sometimes called a shade) is an essential component in outdoor photography and even in a studio where side lighting is being used. It’s designed to shade the front element of the lens to minimize the risk that stray light will strike it. This reduces the risk of flare.
You should have noticed while taking photos in strong side lighting (with the sun to your side) that some images exhibit flare (a bright veil effect that reduces contrast and colour saturation). The effect of obvious flare is visible when viewing the scene through the optical viewfinder. That effect is an example of problematic flare. In a worst-case scenario, you may have noticed weird octogonally shaped “ghosts” in such images, reflections of the lens’ aperture diaphragm. Granted, the effects of flare are not often that dramatic, but even a milder effect is unlikely to be desirable in your images.
Most high-grade lenses do ship with a lens hood but some affordable lenses (of certain brands) do not, in order to minimize the price. That’s understandable since so many consumers are very budget conscious. It’s quite certain that you will be able to buy a hood—made by the lens manufacturer—for each of your lenses. To find the model numbers for the hoods that you need, try a Google search for each of your lenses. The keywords should be the full designation of the lens and the words “lens hood.” After you determine which hoods are necessary for each of your specific lenses, you should be able to order them online from a Canadian retailer. An aftermarket hood is fine too, if it was designed for your specific lens.
Note: Avoid the generic multi-purpose hoods that claim to be suitable for any lens. The depth and diameter of a hood for a wide-angle lens should be entirely different than for a telephoto lens. (That’s also why some hoods, especially for ultra-wide zooms, are of an unusual, petal-shaped design with the corners cut out.) At worst, an inappropriate hood can cause severe vignetting (obvious darkening at the corners of the image); at best, it may simply not be very effective with a particular lens.
As a bonus, a lens hood can offer some additional protection for the lens’ front element. Should you bump into something, the hood should absorb the impact. And in light drizzle or snow, it should minimize the number of droplets that land on the front element. Of course, no such accessory will offer any value if it’s used in the incorrect manner: facing the camera. That’s the way to store it on your camera in the bag, but before you start shooting, remember to install the hood in the intended manner.