FILTERS

The only filters that you really need to produce professional-level images are a warming filter, polarizing filter, and a graduated neutral density filter.

Warming EffectThe filter that I use the most, by far, is the warming filter. It is used primarily in overcast light or in shade to remove the inherent blue or cold light from such scenes. As a result, an amber or warm tonality is added to the scene

Polarizing Filter Effect
Polarizing filters are used primarily to remove glare and can darken a blue sky if used at approximately a 90Þ angle. Here’s the shot on film without a polarizing filter. Notice how flat it is. The colors are actually very vibrant, but the glare is masking, or absorbing,
the color

A polarizer is almost never appropriate for portraiture.

Split Graduated Neutral Density
These filters are amazing in that they make images that are otherwise impossible to capture. These filters lower the contrast range by masking the highlights thus rendering detail in very dark and very bright areas, rather than blowing out the highlights or blackening shadows. The following examples are illustrative of using graduated neutral density filters


UV Filter
The "traditional" visible spectrum runs from red to violet. Red light has the longest wavelength and violet the shortest. Light which has a longer wavelength than red is called infrared, and light which has a shorter wavelength than violet is called ultra violet or UV.

There are basically three color sensitive layers, one sensitive to red light, one to green light and one to blue light. The blue layer not only responds to blue light, but also to UV light, so if there is a lot of UV around the blue sensitive layer gets extra exposure and the final image takes on a blue color.

three filters often used in place of a UV filter (i.e. filters which some photographers keep on the lens at all times as protection). These are the Hoya 81B, the Tiffen 812 and the B+W KR1.5. All three are warming filters in that they shift the color balance towards the red (warm) end of the tonal range.
As you can see all three of the warming filters were effective UV absorbers, as well as slight absorbers in the blue and green regions of the spectrum (which is what makes them warming filters). The polarizer absorbed slightly more in the UV than the visible, though I wouldn't call it an effective UV absorber.

Tiffen 812 . It blocks UV, it protects the lens and it's a warming filter. Some people use an 81B for this, but I slightly prefer the color shift of the 812. Not everyone wants a warming filter, so the clear winner for a neutral filter that really bocks UV is the Tiffen Haze-1, though the Hoya UV should also be pretty effective.