Step-up rings are adapters that allow you to attach filters to a lens when the filter diameter and the lens diameter are different. They seem pretty simple and straightforward. A metal ring and no optics. Even so, there are so many choices that things can get quite confusing. So let’s clear a few things up.
Why use Step-up Rings
Most photographers have a collection of lenses of varying sizes - both in focal lengths and the physical diameter of the lens barrel. For example, I’ve got a 70-200mm f/4 that has a 67mm diameter barrel. I also have a 24-70mm f/2.8 that has a 77mm barrel. By using an inexpensive step-up ring, I'm able to use the same filter on both lenses. That saves a lot of money that I would have to spend on buying filters to fit every lens.
Why the wide disparity in prices?
If you shop for step-up rings you’ll notice a wide disparity of prices for seemingly the same type of step-up ring. I’ve seen a 77mm - 82mm step-up ring for $5 and another of the same size for $34. So what’s the big difference?
You’ll find that the cheap ring may be made from aluminum. It certainly cost less but they are not very strong. They can tend to bend easily, especially the threads, making their use unreliable.
If you’ve ever had filters or rings get stuck on your lens it’s most likely from a process called galling. It’s a combination of friction and adhesion between the surfaces. In severe cases, it can almost be like the pieces are welded together. Aluminum filters and step-up rings are notorious for galling problems - where the filters get stuck on the lenses.
Using a step-up ring, I was able to put a 77mm ND filter on my Canon 70-200mm f/4 lens that has a 67mm diameter.
To fix the galling problems, manufacturers make a hard anodized aluminum version. It’s certainly a better option since the hard anodized surfaces tend to resist galling. But the best option is to use a metal that truly resists galling. Manufactures use brass to make bearings and bushings because they prevent mechanical abrasion. This makes it a perfect material to use for filter rings and step-up rings.
The brass version of our 77mm - 82mm step-up ring costs about $35. Now that’s a big jump from the $5 version. So is a 600% increase worth it? Actually, the answer is yes. With a high-quality brass ring, you avoid just about any problems with the filters getting stuck - that’s the galling problem. It’s often best to pay the extra for a better quality product, even something as simple as a step-up ring. You can avoid so many problems.