Protective Filters

[I mainly use B+W's and Hoya's filters.]

When I order a new lens, at the same time, I also order a protective filter for it. But do you really need protective filters on your lenses?

In film era, most people used UV or Skylight filters as protective filters. UV filter is used to block ultraviolet ray. The effect on the photos is it removes haziness or fogginess caused by ultraviolet rays so the pictures look clearer and sharper. Skylight filters is more or less a UV filter too and add a hint of light pink to make photos look warmer.

Why are these two kinds of filters used as protective filters? They are cheaper than other filters. But the most important thing is that they don't add too much effect to the photos. This property allows them to be left on the lens for almost all the occasions. Also their filter factor is 1, meaning that when you put them on, you don't have to do any exposure compensation. But for almost all the digital cameras, we don't really need to worry about the filter factor. Cameras take care of exposure compensation (will discuss more when touching the so called TTL metering).

Now, let's go back to the ultimate question: does your lens really need a protective filter? For Skylight filters, I now will pass since it add a bit warmer tone to the picture, sometimes you really don't want that. That leaves us only UV filters. Almost all the sensors in modern digital cameras remove unpleasant UV effect already. We really do NOT need UV filters as well. So the UV filter is just a piece of glass to protect the lens.

If UV filters are cheap and also can protect lens, why a group of people are against them? Or why people buy "good" (expensive) UV filters if it's just a piece of glass? To answer this you have to know the reason that UV filter can block UV ray is because of the coating on the glass. Low quality coating not only can't block UV rays, it actually degrades picture quality as well. The point is whenever you put a thing between your targets and the lens, it blocks some light and also potentially disturbs the directionality of the light and that could degrade your photo quality.

My good friend Eric is more on the side of not using protective filters. I said "more" since he also added "unless you use high quality ones". That's your answer why people spend a lot of money buying expensive filters (get better coating and better glass quality).


[I started from Canon's filters. The MARUMI filter is from Japan]

I uses Canon's filters for years, I don't have too many issues with them. But if you have time, shoot the same target, with and without the filter, you might see the difference. I eventually moved up to Hoya's (made in Japan) filters. They are great and not too expensive. For couple of lenses, I can see the difference between Hoya's and Canon's filters. I now also use a lot of B+W (made in Germany) filters, which are considered to be the best filters by many photographers. I don't see the big difference as for the photo quality, really. But why upgrading? B+W uses copper thread, which is different from most other manufactures (most use aluminum). Aluminum thread is softer so when you put on or remove filter very often, you see some tiny aluminum particles left on the lens. When they get into small gap in the front element of the lens, it's very hard to clean. If you don't remove UV filter very often, this should not be a problem. I've also tried MARUMI filters from Japan.

B+W manufactures their filters in different way and that's why they stand out. Their glass and coating are as good as anybody on the market. One tiny thing they did very well is the way they stabilize the glass. Other manufacturers uses three piece solution. They have a housing part, a piece of glass, and a open metal ring squeezed into the housing to stabilize the glass. The problem with this solution is in summer when the weather is hot, the ring expends and sometimes it extrudes and the glass fall apart. B+W uses two piece solution: metal housing and glass. The glass is forged into the housing so there is no moving part. The downside of B+W filters is (you guess right this time) expensive.