The Camera (Part 1) – Know your lens

The Camera (Part 1) – Know your lens

So, you have bought a brand new SLR, or going to buy one. The advertisements say “With Canon 550D body you’ll get  18-55 kit lens” or you have another kit with 18-105 as a kit lens.

So what are these numbers 18-55 or 18-105, look closely and you will get even more confused, you’ll see greek symbols Ø58 and more numbers like f/3.5 – f/5.6 and more symbols like a small flower  with some number next to it.

Let me make it simple for you, we’ll tackle each number separately, taking Canon 18-55 f/3.5-5.6 lens as an example as it is the most commonly used lens.



This denotes the maximum and minimum focal length of your lens. Focal length determines the angle of view, and how much you can magnify an image standing at the same point.

For wide angle lenses focal lengths are shorter while for long range lenses have focal lengths are longer.

So lower number(s) means wide angle lens, and higher number means long range lens.

Lenses with 2 numbers like 18-55 are called zoom lenses whose focal lengths can be changed to zoom in the subject and with a single number like Canon 50 mm are called Prime lenses as these have a fixed focal length.


The f-number is called the aperture of the lens. Generally only maximum apertures (lowest f numbers) are mentioned. A point to note is that f/3.5 and f/5.6 are both maximum apertures. At 18 mm focal length the maximum aperture you can get is f/3.5 but at 55 mm maximum you can get is f/5.6. This is an important point to understand.

Ø58 :

This denotes the diameter of the lens. This is only used when you are buying a filter hood or any other such attachment to put over the lens. Because only a 58mm filter will fit over Ø58 lens.

IS :

The full form of IS is Image Stabilization; for Nikon lenses it is called VR or Vibration Reduction.This technology reduces the blur in an image caused due to hand shake to some extent. This comes in very handy when shooting in low light.

Flower Icon:

The flower icon   0.28mm shows the closest focussing distance, if you move closer than this, the camera will not be able to focus.


So that’s it for the basics. Will elaborate on more specifics in further posts. Till then Bye bye.


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