Thankfully, no. If you needed to buy an all-new circular polarizer, neutral-density or UV filter with every new lens, you’d quickly go broke—not to mention the hassle of carrying multiples of every filter you ever wanted. Instead, you can spend just a few bucks on a device that really is no compromise compared to buying new filters. It’s the step-up ring.
Let’s say you have an existing lens with a 55mm thread diameter, but you add to your kit a new lens with, say, a 49mm thread diameter. Your 55mm filters won’t fit your 49mm lens threads unless you use a step-up ring—in this case, a 49-55mm step-up ring that allows the mounting of a 55mm filter onto a lens with 49mm threads. Simple!
Step-up filters really are simple. Typically made from machined aluminum, these inexpensive devices have a flange with the smaller thread dimension on one side of the adapter, and one with the larger thread dimension on the other. The product couldn’t be more simple—and affordable. I recently purchased a step-up ring in the aforementioned size, and I saw them listed for as little as just $4.95.
There are a few things to consider before you go adapting filters to lenses, however.
First, you want to make sure the ring is black. This shouldn’t be an issue, but in this internet age, you never know. Black cuts down on reflections and glare on the filter glass; the flatter the black, the better. A silver step-up ring would surely increase the likelihood of lens flare and halation.
Speaking of materials, pricier brass step-up rings are available, and if you’re going to use the device regularly you may find it worth it, as the brass rings are less likely to be damaged during use or in the camera bag, and they won’t grab a filter and refuse to let go—which can happen if you mix and match different filter and ring materials. To minimize this, too, look for a ring with dimples or ridges on the outside of the ring in order to help your fingers grasp it for removal of the filter. A stuck filter is no fun, and brass rings with a graspable design make that much less likely, as will some restraint when it comes to tightening the filter onto the adapter. Even these fairly deluxe step-up rings are still affordable; I chose a brass 49-55mm ring with ridged edges and it was still just $20.
Speaking of sizes, it makes the most sense to choose one high-quality filter to fit your largest diameter lens—say, 77mm—and then buy step-down rings as needed to fit your smaller lenses. The reverse, of course, does not work well, though they do make step-down adapter rings for this purpose as well. You can’t very well put a 55mm polarizer on a 77mm lens and expect it to look anything other than terrible, but you might be able to get away with using a 49mm filter on a 52mm lens, or a 67mm filter on a 72mm lens with vignetting at the edges. The exception to this rule, of course, is if you’re using a camera with a smaller than full-frame sensor (such as an APS-C sensor) and lenses built to cover a full frame sensor. Because of the crop factor in this scenario, you’re not likely to see much vignetting by using a 49mm filter and a step-down ring on your 52mm lens, because the lens only sees the central portion of the image circle. That means you can potentially add a larger diameter lens to your kit and use a step-down adapter to make those smaller filters work. The best policy by far, though, is to purchase filters to fit the largest lens diameter you own and use step-up rings to make them work on smaller lenses. It’s one of the most practical, functional and cost-effective camera equipment investments you can make.