YSDIGI Ultra-Slim 40.5mm Circular Polarizer Filter, CPL Protection Lens Filter with Lens Cloth, Multi-Coated, High Definition Schott B270 Glass, Nano Coatings, HD CPL Filter for Outdoor Photography.

As others have noted, the recessed front lens could be a (re)learning curve for some people. Placing a finger on the front (glass) side of the lens does indeed take some getting used to. As a result of this design, the filter is extremely thin. Many UV filters are thicker. Zero vignetting.After some use, I've become comfortable with using it. I'm certain I am turning the correct lens piece, not unscrewing the whole thing. It turns easily, though I wouldn't call it "smooth" or "slick". It does have very consistent friction though (no jumping or sticking).I've seen no distortion or blurring in some 'before/after' shots, nor any color shift. Additionally, I'm only losing ~1 stop. Cleaning has been easy, but I've yet to get hit with tree sap or anything particularly difficult to remove.For reference: I own 3 B+W 010M's on other lenses, and I prefer them. They are smooth functioning, crisp, easy to clean, ...and 4+ times the price of this one. I got this to use on a $200 lens at a rodeo; completely sacrificial. It survived the dust, dirt, and rain, and did a surprisingly fine job doing so. Optically I can't see any difference, functionally this is solid but different to use. Definitely recommended.

Well, it's a polarizer. It works. Unfortunately, the front rotating ring is very difficult to use. You can see from my picture that the ring doesn't stick out much from the filter body at all. Additionally, it's recessed so you're finger can't grab it from the sides easily, if at all. This means that if you want to rotate the ring (like you do with any polarizer) you need to put your fingers more on the front of it, awkwardly applying some force, and spin it that way, instead of grabbing it naturally on the sides.Lastly, it doesn't spin smoothly. It's quite rough and stiff.But, as a polarizer, once it's oriented, it does it's job. It screwed onto my camera lens fine. Didn't come broken or damaged at all.I'm ordering a different filter from tiffen. Looks like a better design, yet still really affordable. Fingers crossed.

After field testing of the 58mm YSDIGI Ultra-Slim Circular Polarizer Filter, I decided to purchase the 67mm and 77mm filters as well. The damping for adjusting the polarization is a bit stiff but is smooth and stays in place once adjusted. The attached unretouched images were shot on a cloudy day, without and with the YSDIGI CPL Filter on a 55mm f1.4 lens mounted on a full frame DSLR. With the CPL filter installed, the haze was reduced and the colors were more saturated, as expected, There was not a notable shift in color cast. These CPL filters seem to be made as well as those costing four times as much and do the job done nicely, without breaking the bank. Too bad YSDIGI doesn't offer ND filters as well.

No diference between the lens of my Galaxy S10 plus and the circular polarizing lens. Seriously!

What kind of thread? Won't even go one turn.

Some of the best filters for lenses. Inexpensive but not cheap.

Well built, metal ring and slim, using on fujinon 23/2.

Wonderful product works well with my SONY... I need to purchase more from them now.