How to Read a Lens

Alpha Tutorial :2 - How to Read a Lens

Lenses are your camera’s eyes, but they’re not just responsible for what your camera sees. They also determine how your camera sees, far or near and how clearly – the same scene shot with a different lens can look dramatically different.

Reading a Lens

Reading a Lens

Here’s how we put this together to read a lens, which normally comes listed with its focal length and maximum apertures (even if it can narrow to smaller apertures).

Say we have an 18-55mm f/3.5-5.6 lens, which means this lens has a focal length of 18-55mm, which gives you roughly 3x zoom from its starting focal length (55 divided by 18). Its maximum aperture is f/3.5, which is only available at the widest focal length of 18mm, at 55mm the maximum aperture is f/5.6.

You can see the lens description on its front, the 18-55 denotes its 18-55mm focal length, and the 3.5-5.6 is its f/3.5-5.6 maximum aperture range.

You can see the lens description on its front, the 18-55 denotes its 18-55mm focal length, and the 3.5-5.6 is its f/3.5-5.6 maximum aperture range.

A lens with only a single aperture setting listed, like a 24-70mm f/2.8, means that this lens can maintain a constant aperture of f/2.8 across its entire focal length, but it can also narrow the aperture using a higher f-number like f/8 if required (to find out its narrowest aperture setting you’d need to glance at its specifications). A lens with only a single focal length listed, like a 45mm f/1.8, means that this lens cannot zoom – this kind of lens is known as a prime lens.

You can also find the lens’ description on the side. In this case, 24-70 refers to this lens’ 24-70mm focal length. When there’s only a single aperture setting shown, in this case f/2.8, that means the lens can retain a constant maximum aperture setting of f/2.8 from one end of the focal length to the other.

You can also find the lens’ description on the side. In this case, 24-70 refers to this lens’ 24-70mm focal length. When there’s only a single aperture setting shown, in this case f/2.8, that means the lens can retain a constant maximum aperture setting of f/2.8 from one end of the focal length to the other.

If a lens has only a single focal length numbered, that means that it’s a fixed focal length lens, also known as a prime lens. In this case, this is a 50mm f.1.8 prime lens.

If a lens has only a single focal length numbered, that means that it’s a fixed focal length lens, also known as a prime lens. In this case, this is a 50mm f.1.8 prime lens.

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