How to check your lens filters size?

When buying filters or lens caps you need to know the diameter of your lens. But you don’t need to break out a ruler. You just need to know the code. And once you know what to look for, it’s easy.

If you’re looking to buy filters, lens caps, or lens hoods, you need to know the diameter of your lens. But you don’t need to break out a ruler. You just need to know the code.

Lens Diameter vs Focal Length vs Aperture

The lens diameter isn’t the same thing as saying a 50mm lens or a 70-200mm lens–that’s the focal length. If you have a DSLR lens with a focal length of 50mm, it doesn’t mean you’d use a 50mm filter–they’re referring to two different measurements.

Nor does it have anything to do with aperture settings like f/1.8 or f/5.6. That denotes the size of the opening to let light in.

Lens diameter is the physical measurement of the diameter of the front-most part of the lens. With DSLR lenses, it’s often threaded to allow filters and lens hoods to screw in. On mirrorless and Micro Four Thirds lenses, some have threads for filters, and some don’t.

There’s no set standard lens diameter size, but there are some common sizes for the diameter of DSLR lenses: 43mm, 49mm, 52mm, 44mm, 58mm, 62mm, 68mm, 72mm, and 77mm. And, in general, you need the right size for your lens–a 72mm filter won’t fit on a lens with a 77mm lens diameter (you can sometimes use an adapter, but that introduces other problems).

How to Find the Lens Diameter

There’s a code, but it’s a simple one. If you see ø52, the lens has a diameter of 52mm, so you’d look for a 52mm filter. Or if you see ø77 it’s a 77mm diameter. And so on.