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Lens Thread Size and Step Rings 101

Finding the right size: It might seem tricky at first, but finding the right thread size isn’t actually that hard. Turns out, you just need to know what to look for, and that’s the universal symbol for diameter: Ø. The lens diameter is different from the optical size of the lens which is expressed in millimeters. If you’re ever confused, just remember that the lens diameter will always have the Ø symbol before the number. And in the rare case that the lens diameter is not marked on the lens, it’ll be in the user guide that your lens (hopefully) came with, or try searching online.
What is a Stepping Ring? 

A stepping ring allows you to use a camera filter that has a wider-diameter thread size than the camera lens that you want to mount it on. Stepping rings are useful in that you can use them to adapt a filter onto a series of lenses of different thread sizes, instead of buying the same filter in different sizes for each lens that you own. Consider the following when purchasing a stepping ring for your camera lens:

How to find thread size
Quality: just like a camera filter or lens, you get what you pay for (yes, there really is a difference between a $10 and $50 stepping ring). You’ll be better off with a quality stepping ring that is machined to the meet the high standards of your camera lens. Stepping rings made of brass are the highest quality and are the least likely to bind to your expensive lens or cause galling (or ‘jamming’). Hard-anodized aluminum or aluminum rings are the next best option. Rings made of polymers or plastic should be avoided. 

Step-up or Step-Down?

If you’ve got a DSLR or mirrorless camera with an interchangeable lens system, chances are  you’ve probably got the kit lens it came with as well as a few other primes, zooms, or telephotos. When looking for a stepping ring, choose one that will fit your largest lens’ front thread size. It’s helpful to first organize your lenses by largest to smallest front lens diameter.


Let’s say you have three camera lenses —one with a 52mm front thread, another with a 67mm thread, and then one with a 77mm thread—you want a filter to fit the widest diameter lens (thread) size, in this case 77mm, and a pair of step-up rings, (67-77mm and 52-77mm), to fit the larger 77mm filter to the smaller-diameter lenses.  Choose a good filter (or set of filters) that fits that lens with the widest lens diameter along with a set of stepping rings to adapt your filters, and it’ll save you from having to replace a damage front lens element down the road.

Stepping Down

Stepping down, if you can avoid it, is not advised. This is because when using a smaller filter on a larger diameter lens, say a 52mm filter on a 77mm lens thread, you run the risk of vignetting around the edges of the frame.  It’s best to step up instead. Also try to avoid stacking stepping rings as that can begin to introduce warping or ghosting into the image.


Stepping rings are a valuable but often overlooked photography tool that provide several advantages. It’ll help you strip down your camera kit to one or two sizes of filters when traveling, instead of taking a filter for each different sized lens and having to sort through them all, (not to mention haul them along with you). A set of stepping rings also costs less than a set of filters, so you’ll be doing not only your physical self a favor by streamlining your gear, you’ll be doing your wallet a favor.

Scott Fairfax  

Chief Copywriter, PolarPro

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