Lens filters can add many enhancing qualities to your photographs. When purchasing a filter, remember that you usually get what you pay for. Hoya and Tiffen are always good filter choices, but are a little pricey. Sometimes, lower quality filters will work fine, but other times, you may have problems such as low performance, low image quality, haze or blur, etc. With a Hoya or Tiffen you are pretty much guaranteed to have no problems. All filters are measured in millimeters, and the size of filter which you need will depend on the thread size of your lens. For example, the kit lens which comes with the Canon Rebel XT is 58mm. You can use larger filters on a smaller lens, or vise versa, with the use of step-up and step-down rings. Below, we will outline the different types of filters, and what they do.

UV Filters - Absorb ultraviolet rays and cuts through far-off atmospheric haze. UV filters also serve as protection for your lens, so it is recommended that you keep them on at all times. UV filters have no drastic image enhancing effect, other than cutting through haze.

Polarizers - Polarizers come in two varieties, Circular Polarizers (CPL) or Linear Polarizers (PL). Generally, linear polarizers are best for manual focus cameras, and circular polarizers are best for autofocus. The reason for this is that with a linear polarizer, many autofocus and metering systems have problems focusing or metering light. When light rays reflect off of a surface, they become polarized. Polarizing filters allow you to basically select which of these light rays you want to allow to pass through. Polarizing filters allow you to remove reflections from any non-metallic surface, such as glass, water, granite countertops, etc. They also increase clarity and vibrance of colors, and drastically improve the appearance of a blue sky. By increasing the contrast between the sky and clouds, and darkening the blue of the sky, they make for some very vivid sky shots.