If you have SLR or D-SLR, you may need to buy additional lens if you really want to make use of that camera. However, buying a lens for your camera can be quite confusing as there are many different types of lenses available suiting to different needs. Buying a suitable lens will all depend on your use and handling capability. Here are the factors that can influence your decision:
What are the lighting conditions?
Aperture defines the amount of light that can get into your camera. Maximum aperture is written in all camera lenses represented usually by a letter “f”. Low aperture means more light can come into the lenses hence giving a bright photo even in low lighting conditions. Similarly, lenses with higher apertures are not suitable for shooting in dark conditions. The latter ones are usually cheaper. For normal photographers, lenses with apertures f2.4 to f3.2 may be enough. If your lenses are zoom lenses and not fixed then the aperture will be mostly written as f2.8-f5.6. This usually means the aperture of lenses in wide angle is f2.8 and when the lenses are zoomed then the maximum aperture is f5.6. Therefore, you would need to be careful about the lighting if zooming.
Wide-angle v/s telephoto lenses
There are two main types of lenses namely wide angle and telephoto, which is determined by the focal length. Focal length is mentioned in millimeters. A telephoto lens allows you to shoot from a distance but they are more prone to give blurred photos, as the aperture is usually high. Wide-angle lenses on the other hand are brighter and hence good for wild life or nature photography where you need to get the whole background. However, it may not be suitable for shooting portrait photos as it gives an impression that the object is farther than the actual distance and hence distorting the picture. Lastly, wide-angle lenses are lighter and more compact than the telephoto lenses.
Zoom lenses v/s prime lenses
Most people go for zoom lenses but it is important to know the difference between the two for you to take the right decision. Zoom lenses solve the problem of having different lenses for different focal lengths. It is written as a range in mm and shows how much you can zoom the lens. If you want to know the zoom capacity of the lenses in simpler terms then divide the higher range by the lower range. For example if the zoom capacity of the lens reads 18-55mm, it simple means the zoom of that lens is 3 times or 3x.
However, some people also like to opt for prime or fixed lenses, as they are not only lighter and smaller but also have better brightness than the zoom lenses. Lastly, it is easier to correct any errors in fixed lenses.
Other factors that you may want to consider
Apart from these top three factors there might be other factors also that you may like to look into like image stabilization, crop factor, image sensors, color refractive correction and focus shift before buying the right lens.
Therefore, buying the right lens depends on your purpose of taking the lens and the kind of pictures you would want to click. When you are buying your lens also factor in the weight and size of the entire camera kit that you want to carry. Lastly, of course price is a very critical part. It is very easy to cross your budget when buying a lens, as there is a lot of variety.