Name: Andy Rouse
Speciality: Wildlife Photography
Q So Andy, what filters do you use?
A I use a combination of skylight / UV and polarising filters.
Q What is a skylight / UV filter?
A A skylight / UV filter is probably the most common filter that you will ever use, as you will rarely take it off. It is a clear glass filter that is designed to protect the front of your lens from dust and scratches, and I have them where possible on all my lenses. You will see various listings for these; sometimes they are called skylight and sometimes UV, which is annoying as the two are slightly different. Skylight filters are clear glass and are just there for protection whereas UV filters protect your lenses as well as cutting down haze. If you are doing high altitude work, a UV filter is vital, in fact there are very few situations where you would ever take one off!
Q OK, what about a Polariser, what does that do?
A A polariser has the same effect as a pair of polarised sunglasses, i.e. it makes a blue sky look better, cuts down harsh reflections and allows you to see into water. That is a simplified explanation, but you know what, it is exactly what a polariser does!! They come into two forms, linear and circular with the latter being by far the most popular. The effect of the polariser is unique and although it can be replicated under Photoshop, it takes a lot of skill and quite some time to do it. Therefore it is better to have one in your bag at all times. The downside of polarisers is that they are fiddly to use as you need to take one hand from the camera to twist them. They also lose two stops of light. This means that if you shoot at 1/250th shutter speed without one then you will shoot at 1/60th with one! Therefore most people only use polarisers on a tripod, although predictably yours truly doesn't!
Q What about other types of filters? There seems to be hundreds out there!
A Yes there are, but most are specialist filters used for balancing colours and for creating special effects such as a starburst effect. One exception is the Neutral Density (ND) filter that landscape photographers use to balance the sky in their images. These come in several strengths and the best are graduated to give a more natural effect. The ND filter is probably the one that is most easily replicated in post processing (with experience), but if landscapes are your bag and you want to get it right at shoot time (which I whole heartedly support), then you would be wise to invest in a couple.
Q Can I use several filters at the same time?
A I have seen great landscape photographers like Joe Cornish use a combination of several filters to get the effect that they want, so yes, it can be done. Screwing one filter on top of another on the front of your lens will lead to a nightmare when trying to get them off however, so many of us use the excellent Lee Filter System to solve this problem. Using this system, the filters sit in a special holder on the front of the camera with slots to hold each one in place. All you have to do is to buy an adaptor for the size of each lens that you have. The system is excellent as it is very quick to remove a filter as rather than fiddling with screw threads (an even bigger nightmare in gloves) and it will even take a Lee Circular Polariser on the front; this is the system that I tend to use and the filter quality is excellent.
Q On the subject of filter quality - how do I know which brand to choose?
A With filters you get what you pay for; the higher priced filters are usually made from Schott glass and have better light transmission. But for most photographers the standard range of filters will be perfectly good enough and you will be able to completely equip yourself for the price of a single expensive one. I use a combination of B&W and Lee Filters and I have bought them all from Wex Photographic.
Q I have a long telephoto lens, do they make special filters for the front?
A For fixed focus 300, 400, 500 and 600mm lenses plus the Nikon 200-400mm you can buy special drop-in filters from the manufacturers that slot in to a special holder in the lens. These include polarisers too, which work by using a small external knob to turn a gear which in turn moves the polariser ring, very clever! I have a polariser for my 200-400 and actually use it quite a lot. To negate the 2 stops of light loss I shoot at a slightly higher ISO on the D3.
Q Is there a problem with DSLR white balance and filters?
A Filters are generally daylight balanced and therefore to get the results you want, you need to set a white balance colour temperature that is close to this. So set your white balance to the daylight setting indicated by the sun symbol. Of course it goes without saying that if you have a non-daylight balanced filter that you need to set the white balance accordingly, or just shoot in RAW and set it correctly at processing time.