Filtration

Filters (image courtesy of http://www.thefind.com/)

The light you get in certain shooting situations might not be the kind or type of light you want. Sometimes the light is too harsh (during mid-day) or sometimes too dull (over-cast days). While the most obvious solution is to reposition yourself in relation to the light source, there are times that this solution won’t work. You then try to reposition your subject in relation to the direction of the light source to get quality out of what’s given to you on a photo-op. However, there are times that this trick won’t work either. Fortunately, there are a tools you can use to alter the quality and color of light that you get by using a simple accessory called a filter.

Lenses can be fitted with a various array of filters. Much like water from your tap where that you filtrate to get the impurities out, “impurities” that a light source presents can be “removed” or altered. There are several filters that you can use so that you can get the effect or quality and color of light that you want. For instance, color filters modify the temperature of light. For example, using an amber filter an hour after sunrise can give you that warm light or warm glow that you want. If your shooting portraits outdoors just around sunset and don’t like the warm glow that the setting sun would bring, use a light blue filter so that you can get a more neutral look for your shot, Just remember, color filters don’t really change light: colored filters enhance the quality of light. There are times when you would have a mixed source of illumination e.g. sunlight coming in through a window plus a fluorescent light. In this type of situation, shoot without a colored filter.

I’ve compiled on a list (shown below) some of filter types you can use to produce a more natural effect depending on the lighting situation. Mind you though, these are not set in stone i.e. you can intermix filters if you want to depending on the artistic result you’re looking for or desire to have.

Condition: Sunny, cloudless day, mid-morning or mid-afternoon.
Filter(s) to use: 81A (amber)
Result/effect: Slightly warm light

Hoya 81C warming filter (image courtesy of http://www.hoya-online.co.uk/)

Condition: Heavily overcast days or rainy days
Filter(s) to use: 81C. This filter has a darker amber hue compared to the 81A filter.
Result/effect: More neutral light; blue cast removed

Condition: Cool light produced by an open shade
Filter(s) to use: 81B The amber color of this filter is lighter than the 81C filter but a bit darker compared to the 81A filter
Result/effect: More neutral light; blue cast removed

Condition: High UV content brought about by shooting conditions in high elevations and light source gives a blue tinge or high UV content shooting under sunny conditions
Filter(s) to use: UV filter + 81A filter. Optional: add a polarizing filter
Result/effect: Reduce hazes and glare. Adding the polarizing filter would give the resulting photo “more warmth”

Condition: Hazy atmosphere
Filter(s) to use: 2A (haze) filter or a polarizing filter
Result/effect: Cuts the haze, produces sharper images

Condition: Fluorescent light source
Filer(s) to use: Magenta filter
Result/effect: Natural look for the subject/scene by cutting out the green haze fluorescent light produces

Tiffen 82A filter (image courtesy of http://www.tiffen.com/)

Condition: Very warm sunset/sunrise light or incandescent light bulb source.
Filter(s) to use: 82A or 82C filter. The former has a light blue tinge/color on the glass while the later has a dark blue color
Result/effect: Counteracts excessively warm tone i.e. removes yellow tinge from the light to produce a more natural look

Condition: Landscape shots with an excessively bright. blue sky
Filer(s) to use: ND-grad (graduated neutral density) filter
Result/effect: Balances exposure for the land and sky so that details would stand out

Condition: Reflections and glare from a water surface, glass surface or a painted surface that removes detail from the scene
Filter(s) to use: Polarizing filter
Result/effect: Removes/reduces glare and enriches colors

ND-grad filter (image courtesy of http://www.penncamera.com/)

One important note to keep in mind when using filters: some filters (like the 82C filter) can reduce the amount of light that is hitting your lens. If your using your camera’s in-body metering system, your camera will compensate for this. However, if you’re metering through a hand-held meter, you need to adjust/compensate manually as reduced light hitting your lens (and eventually the sensor/film) requires longer shutter speeds and/or wider apertures.

Let me touch on the polarizing filter a bit. There are two types of polarizing filters: the circular polarizing filter (CPL) and there’s the linear polarizing filter (LPL). LPLs were commonly used during the heyday of manual SLRS, when auto-exposure and auto-focus was still unheard of. When AF/AE cameras came to be, LPL filters did not produce efficient results, so CPLs were invented. Today’s modern D/SLR has AF and AE so CPLs are the current norm. Unlike the LPL which only has a single element to “filtrate” light, CPLs have a second element that causes light to “vibrate” in all axes for 2nd time. CPLs block polarized light from water droplets and particles from the atmosphere to produce rich, blue skies. On reflective surfaces, such as a placid surface of a lake, the CPL blocks polarized light bouncing of the reflective surface. When using CPLs, make sure that the sun is 90 degrees away from your lens to get the best effect.

Cokin P160 LPL (image courtesy of http://www.amazon.com/)

Ah…you’re also wondering about the ND grad filter. So you like to produce fabulous landscape shots, eh? Good for you! An ND-grad filter sort of looks like a UV filter, except that one half of the glass is gray while the other half is clear. The section where the gray and clear intersect is feathered, sort of fading in/out from clear to gray or vice versa (on which way you want to look at it). During shooting situations where the sky or water is brighter than the land, rotate the filter so that the gray part of the glass is placed over the bright area. Then, you need to place the feathered line on the horizon.

Filters are nifty tool to control the quality, temperature and color of light that hits your lens and as with all tools, you need to practice so that you can master how a specific filter will affect the type of image that you capture on your sensor or film. You need not buy all the kinds of filers that are available on the market. For your kit, you can do with a UV filter, a CPL and probably an ND-grad filter for starters. Just remember to keep the glass of your filters clean so that these babies would produce optimal results.

Happy shooting!