How to Tell the Diameter of a Camera Lens

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 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. Nor does it have anything to do with aperture settings like f/1.8 or f/5.6.

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.

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.

Some of the common sizes for the diameter of DSLR lenses are 49mm, 52mm, 58mm, 62mm, 72mm, and 77mm. A 77mm filter won’t fit on a lens with a 72mm lens diameter (you can sometimes use an adapter, but that introduces other problems).

How to Find the Lens Diameter

But so long as you know what to look for, it’s usually easy to find out because it’s often printed right there on the lens. It might not be easy to spot, because on some lenses it’s etched into the plastic or metal and not easy to see, but there’s a good chance it’s there. It’s one of the few standards that camera manufacturers stick to. So whether it’s a Nikon lens, a Canon lens, a Sigma lens, or so on, the lens diameter is marked the same way.

There’s a code, but it’s a simple one. And once you know what to look for, it’s easy. What you’re looking for is something using the geometric symbol for diameter: ø. So, for example, 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.

Lens Diameter Examples

Here are some examples of what you’re looking for. In these cases, it’s clearly marked in white text. Some manufacturers aren’t quite so considerate though–sometimes you have to look for lightly etched numbers. Sometimes it’s on the outside of the lens, and sometimes it’s just inside the rim. Occasionally a lens won’t have it marked, in which case your best bet is either trial and error or trying to track down a copy of the user manual or lens specs on the manufacturer’s website.

This one takes 72mm filters.

And this one takes 58mm filters.

If Your Lens Doesn’t Have the Lens Diameter Marked

Some lenses don’t have the lens diameter marked on them. In those cases, it’s time to break out a ruler with millimeters marked on it. Or, better yet, some calipers.

What you want to measure is the distance across the widest part of the lens (ie. going through the middle of the circle) starting from the inside rim of the threaded area on one side to the inside rim of the thread on the other side. That then provides the maximum diameter of a filter that will screw into that thread.

Because it’s a rather imprecise way of doing it, here are some common diameters used in DSLR lenses (all are in millimeters):
37, 39, 40, 40.5, 43, 46, 49, 52, 55, 58, 60, 62, 67, 72, 77, 82, 86, 95.

Of those, the ones between 49mm and 77mm tend to be most common for DSLR lenses. If you end up with a measurement for a size that you can’t find a filter for, chances are the measurement is a touch off. The major filter manufacturers don’t make a 50mm filter size, for example, so in that case you’re probably actually after a 49mm filter.

If Your Lens Doesn’t Have a Filter Thread

Most DSLR lenses have filter threads, but not all of them. Some lenses, especially on the cheap end of the market, just aren’t designed for them. But even very expensive specialty lenses can lack a filter thread. Some of them, like extreme wide-angles or fisheyes, often have a very curved front element that doesn’t allow a flat filter. Others, like very long telephoto lenses might have a very large front element that makes a filter impractical. In some cases, they’ll take filters on the other end of the lens at the mount point. If your lens doesn’t have that option and you still want to use filters, something like the Cokin filter system is worth looking into.

View Comments

  • I am new to the DSLR world and was recently gifted a Canon EOS 5D Mark II. The lens that comes with the body is EF 24-105mm f/4. The lens itself says 50mm, but the lens filter that's currently on it says 58mm. Would I stick with 58mm lens filters for this lens?

    • Hi, Carolyn. I'm not all that familiar with Canon's offerings, but as far as I can tell there have been a couple of generations of EF 24-105mm f/4 lenses. There's the EF 24-105mm f/4L IS USM and the newer EF 24-105mm f/4L IS II USM. Both of those take 77mm filters, according to the official Canon specs. I haven't been able to find mention of a version that uses 50mm or 58mm lenses, although they'd be less common sizes for a lens of this type, which I'd normally expect to be more in the 77mm range.

  • The lens cover for my Fuji S8350 42x Super EBC Fujinon lens broke so I want to get a replacement. Unfortunately the size is not listed anywhere on the camera and it is not in the camera manual and the camera does not have a thread. So, I tried to measure and wan't sure where to put the measurement. Should it be across the inner section of the lens, the first rim after the glass piece? If so, then it is a 49mm requirement. The glass section is only 39 mm across so I know that cannot be the correct answer. Thank you!

    • I'm not familiar with that camera, but some vendors seem to sell replacement lens caps listed specifically for it, like this one. Unfortunately, they don't seem to include the diameter either, so I'm not sure if it's a dedicated lens cap or (more likely) a generic one. In general, the measurement is inside the thread where the filter would screw into.

  • I have a D3300 Nikon that came with a Nikon DX 18-35 lens. I bought a wide angle lens online that said it fitted my camera but the thread on my camera lens was too large, and i couldn't get an adaptor to fit. Now i find my lens has a 55mm diameter whereas most D3300s seem to have a 52mm diameter. Why is this? and how can i get something to fit? (i'm looking for a wide angle lens). I'd dearly like to know! Thanks, Pat

    • Are you sure it's not an 18-55mm lens? The 18-35s are much larger. With the 18-55mm, there are a few different versions, and they don't all have the same lens diameter. It is possible to get a 55-52mm step down adapter (like this one), although you're likely to end up with vignetting (black edges) around the image that you'll need to crop out in post-processing.

      From your description, I assume you're talking about a wide angle adapter that screws onto the front of an existing lens? The image quality from those types often isn't great, and you lose features like auto-focus. You'll get much better results from a proper wide-angle lens that attaches directly onto the camera in place of the 18-55mm. And you can pick up some quite good ones that are relatively inexpensive, like this Nikon 10-20mm or this Sigma 10-20mm.

  • I saw a few mentions of the Nikon 50mm 1.8g

    I have the 35mm 1.8g, I think I saw one packaged deal say something about having a 52mm filter. Would that be the correct size for my lens? :)

      • Mine is a D70 with DX on the barrel and it mentions ED!
        What do I need for an 'AF S NIKKOR 18-70mm 1:3.5-4.5G ED'?

        • That lens takes 67mm filters.

          The ED refers to something different. It's Nikon's Extra-Low Dispersion glass that is designed to reduce chromatic aberration (purple fringing).

  • Hi, I have a sony DSC-HX200V, there is a 2,8-5,6/4,8-144 T* on the lens ring, I don't what it means, but i want to get a lens hood and I don't know the size for the hood and the adapter ring.

    • Those numbers refer to the aperture range (f/2.8-f/5.6) and the zoom range focal lengths (4.8mm to 144mm). I haven't used that camera, but from the specs it doesn't look like it has a filter thread on the front of the lens. So unfortunately it doesn't look like it's a standard size or fit. It does look like there were some third-party adapter rings made that added a filter thread to the front of the lens, but I can't speak to how well they work and they don't seem to be readily available anymore. But in theory, an adapter like that would let you add a regular lens hood. Without a thread or adapter, it is technically possible to do it, but you start getting into more serious DIY options that can get messy.

  • Yes, it's confusing, unfortunately. The 50mm in the lens's name is referring to the focal length (or magnification). That's referring to a measurement related to the path the light travels from the front of the lens to the back of the lens (although it's also not a direct linear measurement referring to the physical length of the lens).

    What you want is the lens diameter, which is the measurement across the front from one side to the other. The Nikon AF-S Nikkor 50mm ƒ/1.8G has a lens diameter is 58mm. Here are some 58mm UV filters that will work. The model number of the original Nikon-branded hood for that lens is HB-47. You can also get aftermarket versions that are substantially cheaper but do the same thing, like this one.

  • Hello...
    I have a Nikon d3400 camera with Nikon 50mm 1.8G Lens. I need to buy a hood and UV filter for it. But i am confused as 50mm hood and filter's are not available. what to do? should i use 49mm or 52mm instead.

    thanks in advance.

  • I have a canon sx530 50x and I know I’m not going to sound the smartest but I want to get filter lens’ for it but I don’t know how to find out how many mm my camera lens is... can u help?

    • I haven't used that camera, but in looking at the reference manual (p.136), it looks like you'll need to get a specific adapter that goes onto the lens that then allows you to screw on 67mm filters. The model number is Canon Filter Adapter FA-DC67A. Once that's attached, it looks like any standard 67mm filter will work.

  • Hi.
    I have Nikon d5600 with kit lens AF-P DX NIKKOR 18-55mm f/3.5-5.6G VR + AF-P DX NIKKOR 70-300mm f/4.5-6.3G ED VR. What nd filter size and lens hood should I use?

  • I have the Canon 800D with 18-135mm lens .... On the front of lens it says 67mm. I want to buy a 50mm wide angle lens.... Is there a lens for under $300 Au What do you suggest?

    • A 50mm prime is an excellent choice as a versatile prime. On the APS-C sized sensor of the 800D/T7i, it's equivalent to a 75mm perspective on a full-frame sensor. So it becomes a very slight telephoto--a good, fast, and inexpensive option with a flattering perspective for portraits.

      And the good news is that 50mm primes are inexpensive, small, and sharp. Canon has a 50mm ƒ/1.8 that's a very good place to start, for USD$125.

      If you're shooting a lot in low-light conditions or one some extra blurriness in the background and your budget has a bit more room, there's a ƒ/1.4 version for a bit over double that. There are also many options for more specialized versions, but those are the two I'd be looking at first.

      If you want something a little wider that results in close to a 50mm on a full-frame sensor, you can put on a 35mm focal length that comes out to around 52mm equivalent. They're a bit more expensive than you have in mind and not quite as fast but still a good option.

      And because 50mm primes are such a staple, you can usually find very good ones used for reasonable prices. In the US, I usually buy my used gear from KEH or B&H, but there are also good options in Australia (I'm originally Australian), including eBay. Just be sure you're getting the precise model number you want, because there are also a lot of older 50mm ƒ/1.8 and ƒ/1.4 models that are manual focus, for example.