How can you find your Lens Focal Length?
When you look at your camera lenses you see many different numbers. These numbers can be very confusing when you just started photography. In this article I am going to talk about the Lens Focal Length and different uses of various Focal Length.
What is Lens Focal Length?
The Lens Focal Length is stated by millimetre (e.g. 35mm, 50mm, etc.) on your lenses. The focal length of the lens is the distance between the lens and the image sensor when the subject is in focus. There is tons of information about the technical aspects of lens focal length, and in this article I am not going to go in depth with these technical aspects.
Where Can you find the Lens Focal Length?
Usually by looking around the lens barrel, or on the front of the lens, you would see many numbers including the lens focal length followed by mm (millimetre). In the below pictures I marked the lens focal length in two different lenses
Lens Focal Length
Zoom lenses and Prime lenses
If your lens focal length is a range of numbers (e.g. 18-55MM), it means that you have a Zoom lens. A zoom lens is a lens with variable focal lengths. Whereas a Prime lens is a lens with one focal length. A zoom lens can be a wide angle, wide to telephoto, or a telephoto zoom lens. Which takes us to the next topic of Lens focal length and Angle Of View.
Zoom lens focal length
What is the Lens angle of View?
Angle of view is a measurement of how much of a scene or subject a lens can cover and take image. Expressed in degrees, the angle of view can be measured horizontally, vertically or diagonally across an image. The angle of view depends on the size of the sensor as well as the lens focal length. The larger the sensor the wider angle of view. For example a 50mm lens has more angle view on a full frame camera than an APSC size camera.
General rule to remember
To make it easy to remember we should know that any lens focal length smaller than 35mm is considered as wide-angle and any number higher than 50mm as a telephoto (in full frame and APSC DSLRs).
Lens Focal length is 24mm
Lens Focal length is 50mm
Lens Focal length is 70mm
Lens Focal length is 200mm
Lens Focal length is 300mm
Lens Focal Length and Camera’s Shutter Speed
As a rule of thumb the camera shutter speed should be higher than the lens focal length to avoid blurry photos (camera shake). For instance if your lens focal length is 85mm, the safe shutter speed is 1/90s faster to reduce the chance of a blurry picture.
Do you want to learn more?
I cover Lens Focal Length in depth in our Digital Photography Bootcamp program. This is a six week, eight session program and includes two field trips. This is a complete photography class for beginners to intermediate photographers who want to start the photography as a business or just for fun and getting creative.
Ted and the Omnilargess Team