HOW DO WE GO ABOUT CHOOSING A LENS FOR OUR NEEDS?

Figuring out which lenses will suit our specific needs is not that simple.There are hundreds of lenses presently available across the major lens makers. Thus how do we go about choosing a lens for our needs?Selecting a lens is totally different game to selecting a camera, and it’s complicated by the fact that two lenses often appear the same on paper however vary in price considerably.

There are several abbreviations and specifications we need to know, and different manufacturers use utterly different abbreviations for exactly the same properties. The  process of  narrowing  down  the selection to a handful of options is stressful.

APERTURE

Most apertures are stated on all lenses. Aperture is provided as an aperture number, such as f/2.8.Higher the aperture number, the cheaper is the lens. It tells us how much light the lens can get through to the sensor at its best. Much light means we can keep shooting in darker conditions without the image blurring due to camera shake. The smaller the aperture number, the more light entering the camera. In practice the brightest lenses offer a maximum aperture of around f/1.2, but theoretically the absolute best aperture you can get is an objective equal to one. Most consumers will be satisfied with an aperture number of between f/2.4 and f/3.2.

IMAGE STABILIZATION

There are some cameras having image stabilization built into their bodies while some others employ the technology in their lenses. We should consider a lens with the technology built into it, if our camera lacks image stabilization, as this will help us to achieve sharper images.Most systems allow us to take images up to three of four times slower than you would otherwise be able to. Image stabilization is particularly useful with longer focal lengths as images requires faster shutter speeds here to keep them

CROP FACTOR

Different sizes of image sensors are used by various camera manufacturers in their SLR cameras. This can cause confusion in relation to figuring out the actual capacity of a telephoto or wide angle lens. Convert the focal length to the full frame equivalent is the most common trick. We need the crop factor to make the conversion. For example, on Canon’s SLR cameras without a full frame sensor, the crop factor is 1.6. This means that we have to multiply the focal length by 1.6 to determine what it would have been on the 135 (full-frame) formats.

COLOR REFRACTIVE CORRECTION

Photography focuses entirely on the light. Different colors of light bend differently when they pass through a lens,this strange abilities of light is a headache for lens makers that lead to color shifts, particularly toward the edges in an image. To counteract this, manufacturers are using what they call a low dispersion glass.

DISTORTION

In distortion, the straight lines at the edges of the image are bent either inward or outward. During construction most lens manufacturers take this into account and correct it in the best possible way, but still come across specifications indicating that the lens has correction for this distortion.

PERSPECTIVE / FOCUS SHIFT

When shooting a high building we point the camera slightly upward, and the building looks thinner on top than the bottom. Some lenses have the ability to correct perspective. Lens perspective shift can rectify this. Lenses also have the option to change the focus plane so that we can improve or worsen the depth of field.