Why is the Lens so important?

So, why is the Lens so important (I mean camera lens here)? Why so many photographers or experts say that the lens is more important than the camera?

Let’s start by looking at how the lens works.

Camera lensessource:Wikipedia, author: Bill Ebbesen

How the lens works

Lens is a number of glasses put together to filter the light through to the camera sensor (or film in the past). The main job of a camera lens is to focus light onto the camera sensor. It seems like a simple job, but it’s actually very complicated. You want the image to be sharp all across the image not just in the centre as an example and that’s not that easy to accomplish. And it gets even more complicated when we talk about the zoom lenses. It is so much more complex with zoom lenses as the lens needs to keep on focusing correctly as you change the focal length. It is a complicated stuff with a lot of technology involved.

Let’s talk about focal length.

Focal length

Something you’ll find out from the Focal Length is the field of view. Focal length is actually a very important part of a lens specification. If you’re new to photography, a focal length of 50mm is a standard – a lens with 50mm focal length is a standard lens. In the past if you were to buy a new camera (a film camera), you would get a 50mm lens – usually 50mm F1.8.

The shorter the focal length of the lens, say 35mm or 28mm, the wider field of view, and that’s why these lenses are called “wide angle lenses”. The longer the focal length of the lens, say 100mm or 200mm, the narrower field of view, and these lenses would be called “telephoto lenses”. Prime lenses, lenses with one focal length, are of better quality than zoom lenses. Zoom lenses, on the other hand, give photographers the ability to take photos at different focal lengths without the need to change the lens. But it comes at a price – quality. If the quality is your primary concern, go for prime lenses (if you can tell the difference in the quality of images of course).

Aperture

Aperture is another very important factor to consider when purchasing a lens. Aperture is described in numbers, from F1.0 through F2.8 to F32 and more, and it describes the size of the opening in the lens that allows the light to go through. It is measured in F-stops and it is described as a fraction of the focal length. So, basically the bigger “number” the smaller the opening in the lens. Let me give you an example:

  • you use a 50mm lens and you set the aperture to F4 – the diameter of the opening in the lens will be 12.5mm (50/4 = 12.5)

The bigger the opening in the lens (the lower F-stop value) the more light gets into the lens and onto the sensor. That means you get more light to work with. That’s why the lower F-stop value, the more expensive lens (50mm F1.4 is more expensive than 50mm F1.8).

More on the subject in future posts.

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