You have seen and unscrew that extra protective ring in front of your photography lens. Dimitris explains what is that and why is needed. Read along.
On our photography lens we must always mount protective filter (from the first day we get them). That filters usually screws (in most lens) in the front side (see note at the end of the article) and protects our lens from dust, water drops, finger stains and more. Yet, the most important reason is the protection it provides from scratches and bumps.
The protective filter must be always on our lens. The usual choice is a UV protective filter (Ultra Violet).
In the old days, we used more such filters, like the Skylight ones, but they were not color neutral and they reduced the presence of blue color. UV filters were made to cut out utraviolet radiation, but they are color neutral and they are ideal for protecting lens. That is the reason they are mostly preferred in this digital era.
You may also find them labeled as “PROTECTOR”, without specifically mentioning the UV filtering.
Things to know in choosing a UV filter
The selection of a UV filter must be done with caution. No matter how chromatically neutral such can be, it can affect photo quality too (by affecting lens quality) if it comes from a non-reliable manufacturer. UV filters usually come in gradations when it comes to their quality, and price follows as such.
The ones with highest quality (and price) are usually marked as PRO. Companies with best reputation in such filters are HOYA, B+W and NISI. Good ones also come from NIKON and CANON, while there are companies with cheaper filters and quite reliable. The latter are MARUMI, KENCO, WALIMEX, VISICO and more.
Another important factor in protective UV filters is their thickness. In wide angle lens or in open baffles in some lens, a thick filter may produce a vignette effect (a darkening at the edge of the frame). For such cases we choose a SLIM filter, that is less thick than the usual ones, specialized for such lens. The UV SLIM filters are needed when we are about to use some extra filters on our lenses; for example a polarized filter (PL) or a neutral density one (ND). In such cases and because we don’t want to unscrew the UV filter all the time, it is better to have thin UV filters so we can mount more filters on top of them.
Note: There are lens (usually ultra-wide and fisheye ones), where due to their curved front element that protrudes too much, there is no thread to use to screw filters. In such lens we usually adjust a filter carrier system. In other lens there is thread in their back side and there we can also screw additional filters. Some special lens have a filter carrier embedded on their main body.
This article is a translation of a Greek one, originally written by Dimitris Asithianakis. Dimitris is a professional photographer and a teacher of photography as well, based in Athens, Greece.
Read another one for Jumpology in Photography!