If you scratch the surface of SLR photography, Zoom lens is what you see on almost every DSLR. To be able to zoom in on your subject and capture details what your eyes can’t see is something that excites everyone. And so, this is happily paired with every new DSLR you buy.
Fondly called the kit lens, a usual 18-55mm glass gives you the hang of what the world through a big detachable lens looks like. How much zoom is really the 55mm zoom and what all things you can keep at its widest possible 18mm frame; or how auto focus behavior changes with zoom and aperture effects that play out at different F numbers. With time, it becomes your pet walk around lens that you can learn on.
Photo by Rahul Sethi
Unlike with point and shoot cameras, zoom lenses are not measured by how much times they can zoom into the frame (like 20x zoom) but are named according to their focal length. If they were, it will be different for different lenses, since zoom is always relative not related to a same base value (or zero zoom, if you will). So you can find out zoom for a particular lens by dividing the larger value with the smaller one. To say it, a 50-100mm lens will have 2x zoom, usually called power of the lens. But that’s a rough figure when focal lengths are expressed in their ‘35mm equivalent’.
Now, zoom lenses are not just run of the mill lenses that you could learn on. They come in various focal lengths ranging from the usual 18-55mm, to telephoto zoom 55-300mm or super telephoto 300-500mm and more. They play a crucial role in professional photography when it comes to shooting ferocious animals from afar, high flying birds, fast cruising superbikes and people in candid.
But zoom lenses have their drawbacks. Shooting with a 55-300mm lens is not the same as shooting with a 300mm prime.
What is a prime lens, you ask?
One needs to have experienced every nitty-gritty of an 18-55mm (or any other zoom lens) in order to understand the benefit of a prime. Unlike zoom lens, the focal length of which can be varied, prime lenses are essentially Fixed Focal Length (FFL) lenses.
Now, why would someone use a lens that can’t be zoomed in? Every lens is made up of smaller lens elements that help it achieve the desired effect. It’s not rocket science to understand that lesser the elements, sharper will be the image, as the light goes through lesser “glasses” and hence less is the chance of it getting modified in any way. The 18-55mm lens, for example, needs at least twice the elements required to make a 50mm prime.
Moreover, a prime lens drastically reduces cost, chromatic aberration (colors appearing around objects when there aren’t any), vingnetting (different brightness levels at center and edges) and the need to pump up the ISO.
And the only drawback – you need to zoom using your foot. But your image is much sharper, clearer in focus and sometimes, nothing like you could have captured from the 18-55 kit lens. Pro shooters always keep a prime lens handy; many are likely to keep only a prime while doing street or casual photography.
Photo by – Maurice Etoile
A 50mm prime has an aperture of at least f1.8 which is around three times wider or more correctly, 3 f-stops ahead of what you get on kit lens at this focal length. This can give softer backgrounds or put them completely out of focus, making the subject stand out, which is very much a requirement in portrait photography. Wider aperture means more light, hence you need not pump up the ISO of your camera and go deal with noise on software. This also means a cheaper camera can do the job. For shooting food, portrait or people on street, 50mm is the go-to lens.
Photo by – James Demetrie
In many cases 50mm gets too close to things. To frame buildings or architecture from far away, for example, especially in the night it does a great job. But you might not get the space to back up and frame that perfect shot at times. This is where a wide-angle prime lens comes to work. All the benefits, features and versatility remain same as a prime. But you get a wider frame that takes in more things, if the composition demands in limited space. That is why, a wide-angle lens comes in various focal lengths – 10mm, 14mm, 18mm, 20mm,24mm or so up to 35mm. Generally, smaller the focal length, costlier the lens.
Wide primes are indispensable part of a kit for shooting landscapes, architecture, sky, a wedding or sports event.
Photo by – Adolf Abi-Aad
A Macro lens is used to get a magnified view of an object, getting very close to it. Though there are separate lenses available for this purpose but if you want to capture the big handsome face of a tiny insect you can use macro tube attachments or reverse mount a compatible prime lens. Some zoom lenses have a built in option to be converted to a macro lens and are called the Macro Zoom lens. Like this Tamron lens comes with a button to switch between normal and macro mode.
Macro zoom lenses are good for fun and take quite good images. Besides, its two lenses built in one. But a Fixed Focal Length Macro lens is always recommended for sharp and clean images; for the reasons you now know.