Grab your kit lens and take the lens cap off the front and you’ll find a series of numbers that will help you figure out what the technical specifications of your lens are and what you may want to consider picking a new one.
1. 1:3.5-5.6. This is the maximum (or widest) aperture of your lens. The reason it’s written as an interval is because the minimum aperture depends on the focal length that the lens is being used at.
2. 18-55. This is the focal length range of the lens. The widest angle is 18mm, and the narrowest focal length is 55mm. Importantly, the maximum aperture is f/3.5 at 18mm, and f/5.6 at 55mm. Depending on the lens, the aperture will stop down as you zoom in.
3. 0.25m. This is the minimum focussing distance, and is important for macro lenses. All it’s saying is that anything closer than 25cm to the camera sensor (not the front of the lens) will be out of focus. If you’re interested, on top of your camera is a symbol that looks like a circle with a line going through the middle, which reminds me of a picture of Saturn. This is where the sensor sits.
4. ∅55. This is the filter thread on the front of the lens in millimetres. If you want to attach a filter to the front of the lens, it’ll need to be the same size to fit on front of the lens.