In photography and cameras probably the least understood, underused and underestimated piece of equipment is possibly the lens hood. It is made worse by a perception that it is an accessory used by photographers for them be perceived as more serious. All of this is far from the truth. The lens hood is probably among the underused and under estimated accessory. The importance and criticality of the accessory could hardly be questioned though, hardly a surprise that many lens manufacturers provide hoods with their lenses to customers, at least the higher end costlier lenses tend to sure do so.
What function does the lens hood serve? In broad the lens hood keeps away stray light, side light away from the lens, giving one sharper, better quality pictures and avoiding lens flares. Like most other features akin to a camera and photography, one could correlate this with how we use our eyes and our vision. On a bright day, or when there is a bright source of light, we tend to cup our palms over eyes and shade it, not allowing the stray and side light to fall on our eyes, allowing us to see better, with more clarity and sharper images. Pretty much what the hood of a sun cap does. This is the exact same function served by a lens hood.
There is one other significant purpose it serves, non photographic though. One would imagine it was more an unintended fallout rather than planned. Lenses are very costly and susceptible to damage, scratches, abrasions and so on. Possibly, it is every photographer’s nightmare, to see his or her camera fall and land on its lens. The lens hood also serves the purpose of protecting your lenses, when it falls straight down. Many a lens have been saved at the cost of a shattered lens hood and lot less damage to the wallet.
Few of the questions one hears are: 1) Does one need a lens hood? 2) Do they work? 3) Are there times it does not work? 4) Is it needed, is it essential? 5) Does one need to be careful while picking a lense hood? The answer to all of them is `yes`, we will try to reason them all out briefly
Lens hood protects the lens from side light, stray light, rather in one word the unwanted light. That is of course if one is not shooting into the source of the light itself. It ensures that lens flares are avoided or minimised at the least. The makes sure that the light does not wash over the photograph, leaving the images sharp and clear and the contrasts maintained.
Do they Work? Yes they do, and works perfectly with lenses that have fixed focal (prime lens). These lenses tend to have longish tubular hoods, protecting the lens from all wayward light. The lens hoods have an inner lining of felt, velvet or rubberised coating to minimise the reflection of the light from the hood’s inner surface.
It does get a little more complex with the Zoom Lens, the variable focal lengths add to the challenge. The zoom lens hoods tend to be more open and curved that allows for the field of view which is wide in shorter focal lengths. The hoods work fine when operating on the longer focal lengths. One could safely say that the hoods are variably effective on zoom lenses depending on the focal lengths, angles at which the photographs are being shot with respect to the light source etc, effective none the same. Hoods are not effective when one is shooting into the light, It protects from reflected, light, stray light, side light and so on.
Is it needed, essential? Does one need to be careful while picking up a hood? A big `yes` to both. We have seen enough reasons to deem it essential. The right hood for the right lens. In all likelihood, the hoods that come with the lens are perfect for them, they will have been designed with the lens in mind. If one is picking up a hood for the lens, it is good to have a basic understanding of the lens and the requirement.
Hoods come in different sizes and shapes. Picking a hood for a prime lens is a relatively easier task, a longish tubular hood ought to work fine. The pitfalls of the same, we will see when exploring zoom lens hoods. While picking the right size of the hood, be careful of these: too long and the hood could cause vignetting, a phenomenon where the edges become dark, because the light has been partly blocked. It is critical to pick a hood that is not too long, or even better to have different sized hoods for different focal length adjustments. One would need to experiment and explore different focal lengths with different hoods and arrive at the appropriate ones. This complexity has also given rise to different shaped hoods, to enable wide shots and the needs and requirements at varying focal lengths on the zoom lens.
Rectangular Shaped Hoods: The final image is rectangular hence the the rectangular hood is a good choice and is generally longer and so protects and blocks more unwanted light and by far is preferred over the round ones.
Tulip Shaped Hoods: Also called the petal shaped hood by many, is a good choice overall. The hood can rotate, and it has longer petals, which can be positioned to block away light from a source yet leave other sides relatively open and is said to improve the angle of view.
Circular Shaped Hoods: Is the least used of the lot, as it has no inherent advantage since the final image is rectangular and gives no additional protection from wayward light.
Adjustable Bellow Hoods: These are expensive hoods but more effective, since the lens hood can be adjusted more precisely for a given focal length to provide a more appropriate match for the field of view.
Carrying multiple hoods can be cumbersome, since they are big and heavy. It takes a lot of space and adds to the weight of the equipment bag. None the same they are effective and one is better off carrying them. The hood can be attached in the reverse while storing for long term on the camera as it saves place, but does not protect the lens as well.
If for some reason you have not carried hood, use your hand, books or other objects to shade, block the light and stop it from falling on the lens. Ensure though the object does not fall into the frame of the picture. Shooting with the light source from behind or from a shaded area would also help.