Actually, you don't need a UV filter anymore these days, because camera manufacturers have been installing such a filter in front of the sensor for many years. However, there is one application in which a magnetic filter is useful and practical: If you have already fitted your lens(es) with a magnetic filter adapter, then a lens hood will generally no longer fit. However, this offers the best protection against, for example, accidental bumping. Without a gel, the front lens is exposed. And that's where this UV filter comes in, but a neutral glass filter would have done just as well. Now, filters generally have a negative effect on image quality, the only question is how much. This filter is very cheap at around 20 euros (67 mm) and I think the quality is OK. Flares (backlight that leads to unwanted reflections within the lens) seem to be much stronger to me, but it depends a lot on the lens anyway and a lens hood is always better than a better filter, unless you can avoid flares or even use them deliberately. There are two aspects of handling that bother me: the filter box is designed for much larger filters (I estimate 82 mm) and does not have a suitable recess for this 67 mm filter. This means that not only is the box much larger than necessary, but the filter also rattles around in it during transport. Solution: use your own filter bag, in the right size. The magnetic holding force between the filter and the lens adapter is weaker than that between the filter and the front cover. If you take the front cover off, this UV filter is always attached to it. For 20 euros, this filter is extremely cheap, technically/optically OK, but in practice it does show some small weaknesses. The fact that you basically get protection that can be removed quickly and that you don't have to spend a long time screwing on makes the filter still worth recommending.