Maybe you're new to step rings and/or filters, maybe you find yourself in a pile of lenses and about to empty your wallet to get filters for them all. In any case, you've found the right place.
What are step rings used for?
Typically you have lenses that each have different front filter thread mounts. If you want filters for all of them, your choice is either to buy a filter for each size you own, or get some step rings. The step ring route is far cheaper, but isn't without downsides. Some lens's detachable hoods won't mount correctly when using a step up ring, and on certain ultra wide angle lenses, a step ring may cause the edges of the filter to be visible in the frame.
Keeping those limitations in mind, let's have a look at this very inexpensive, very extensive set of step up and down rings.
I wasn't expecting the highest quality at this price, but i already have most of what i need in step rings already, and just wanted the whole shebang around for those just-in-case scenarios. Here's the rundown:
-A few reviewers mentioned incorrect sizing, the ones I recieved all come together(see photo)
-Quality seems just fine, labeling is very clear and nice
-Made of Aluminum, If you want premium; pay more and go for brass rings.
-All came individually packaged, clean, no residue.
-The threading is OK, a little gritty.
-To prevent getting stuck, you can apply a TINY amount of lubricant/Vaseline on the threads using a Q-tip (hesitantly recommended)
Step down rings?
Step up rings are more widely used due to the above mentioned issue of filter edges showing up in the frame. But in a lot of situations you can safely use a step down ring. If you're using a cropped sensor camera, such as an APS-C or micro 4/3, you can use a step down ring if you're using a larger format lens on that particular camera/sensor. So, for instance if you have a canon 70d, and a 50mm 1.8 lens, you can likely get away with stepping down to 43mm(not a recommendation, just a for instance)
Brass is the best choice for step ring construction, it is hardy, and isn't very prone to sticking. Unfortunately you get what you pay for, and brass is typically found in more expensive step rings. This set is made of aluminum, which is light and strong, and overall works just fine. It does however tend to get stuck more often. On the occasion, I have applied very small amounts of oil to such threads to help with this issue. Grease/lube around lenses and gear is not ideal, but neither is a stuck thread. If you do lube yours up, do so super very incredibly sparingly and clean up any excess.
All in all its certainly a great deal, just be aware they aren't high end and likely will be more prone to getting stuck, so don't over-tighten and apply some lube if you are OK with the downsides of doing that