I remember last year, when I was going through all entry level DSLRs to choose a perfect camera for myself, it was a mess. I had to make sure that the camera I would finally choose should be very flexible in terms of lenses, filters and storage. And now, after many highs and lows I have finally learned that even with a high end DSLR, one might not be able to get great images if he or she does not use an appropriate lens, but with even a mediocre DSLR and an appropriate lens one can get great images.
Photography can be broadly classified into two types: Landscape Photography and Portrait Photography, and one can also classify photography based on different styles as well: Night Photography, Street Photography and Macro Photography.
Before I proceed into categorizing lenses for the specific style, let me first describe the two fundamental parameters of an optical lens- Focal Length and Aperture. If you understand these two fundamental parameters, you can easily choose the right lens for your particular needs.
- The lens’s focal length determines the magnification of an image projected into the camera and the angle of view,
- Aperture determines the light coming in through the opening of the lens, and the image’s depth of field.
The focal length’s range of the lens is inscribed on it. As the focal length of the lens increases, the image projected on the camera becomes more magnified, and the angle of view becomes narrower. Hence, more the focal length of a lens more is the magnification one can get, but less area will be covered in the image.
Maximum aperture range is also inscribed on the lens itself. With increase in aperture, which is identified by a smaller f-number, the intensity of light coming into the camera through the lens opening increases, and the depth of field of the subject also increases.
Depth of field is a concept which determines the clarity of subjects in the image. You would not want a landscape image to be focused on just one portion; if everything in the image is clear and focused, a landscape image will look much more prettier i.e. the image should have a very narrow depth of field and when one clicks a portrait, it is generally desired that only the subject is in the focus and the background is very soft which means the image should have a very shallow depth of field.
To obtain these kinds of images, one has to play with aperture/f-numbers. For a landscape shot, to obtain a narrow depth of field, the lens should have an option of higher f-numbers (greater than f/10 and as high as f/22) and for portrait photography, for which the user requires a shallow depth of field, the lens should have a very wide aperture i.e. lower f-number of upto f/1.4 or f/1.8, though soft background and perfectly focused subject can be attained with slightly higher f-numbers as well (f/4 or f/5), but the effectiveness of a portrait keeps on decreasing as the f-number increases.
Talking about focal length of a lens, its concept is totally different from aperture. Focal length of a lens determines the magnification and the angle of view. Lenses can be categorized into 3 types based on focal length-
With the angle of view of diagonal of about 50 degrees. Lenses with minimum focal length of 18mm can be put into this category. They have a sufficiently large field of view and even today I pack my 18-55mm lens for various photo trips. It was the basic lens that I got with my camera kit. I like working on 18mm for Landscape photography and later stitching the pictures to create panoramic photographs.
With the angle of view of about 60 degree or large. Lenses with minimum focal length 10-17mm are generally referred as the Wide-Angle Lenses. With a single image with this lens, one can cover a large field of view but the image might have some distortion at the sides as it might seem to be a little curved towards the vertical edges, but personally I love to use this distortion to create effects.
Long-Focal Length Lens or Telephoto Lens:
Lenses which have the capacity to magnify the image projected into the camera to upto 20times. Telephoto lenses are the ones which have focal length of upto 300mm or even higher and generally start with 55mm, 70mm or even 18mm. They have an edge over normal lenses because even if the subject is at some distance one can still get a perfectly framed close-up. Due to some manufacturing restrains telephoto lenses cannot be manufactured with large apertures (maximum aperture of a 300mm or 200mm focal length lens available in market is f/4-f/5.6) hence, high depth of field is difficult to attain, flatter images in comparison to the images clicked by the prime lenses which have large apertures (f/1.8, or so).
As the focal length of a lens increases, the angle of view decreases. Take an example of a bus as a subject and two lenses: a wide angle and a telephoto lens. Assume all other conditions to be same. To include entire length of the bus in the frame with a telephoto lens, with its high focal length, one has to stand very far from bus, but with a wide-angle lens, one can include entire length of the bus in the frame by standing just a couple of metres away from the bus.
Now that I’ve listed and explained the two basic parameters of a lens, you should be able to judge which lens you would need if you have to go for a Landscape or Portrait Photography.
Summarizing the entire concept, to capture a landscape, you’ll need a lens which has capabilities of higher f-numbers to obtain narrow depth of field and large angle of view which is possible with focal length of 10-18mm or slightly higher than 18mm. For portrait photography, you’ll need a soft background and a very shallow depth of field, which means large aperture i.e. lower f-numbers of upto f/1.8 or f/1.4. These large apertures are generally not attainable in telephoto lenses (zoom lenses) as I mentioned above. One can get this particular specification of large aperture easily in prime lenses. A prime lens has only one focal length so no zoom in or zoom out is available. To include the subject in the frame, you’ll need to move back and forth for perfect framing. They are cheap and give excellent results; also you’ll get very sharp images with a prime lens because of its engineering. They have very less elements in their body hence less light loss so clearer images.
Then there are macro lenses, which are specifically designed for shooting objects up close. A true macro lens will produce images which are life size and enable you to get in quite close to the subject. Now, various telephoto and prime lenses have an option which allows the user to switch to macro photography and surprisingly they give excellent results too, so you can go for the combo if you need your lens to do a little more than just macro.
For night photography you don’t need a special lens. You just need to know the technique. You can go for night photography with almost all kinds of lenses. And even for street photography, you don’t need any specific type of lens, though the lens which offers decent focal length of upto 105mm or 135mm or even 50mm and with a large aperture of at least f/3.5 might help you a lot. One can also go for the telephoto lenses for street photography, but attaining a very shallow depth of field is not possible, which can be compensated if you have nice background which suits the subject.
And after all a camera is just an instrument, you need much more than a couple of equipments to get great images, you need to have a heart for photography.