What is a Polarizer?

If you’re a photographer who shoots outdoors a lot, you’ve likely scrutinized closely the outdoor photos from other photographers, and in doing so – you may have noticed deep blue skies, crisp lines on green surfaces, or generally higher contrast. These are pictures that were (in all likelihood) shot through a polarizer.

What a polarizer does is to remove stray waves of light, which cause reflections. By doing this, they can increase the clarity of foliage (which often reflect a degree of light), remove the reflection on the top of water, and increase the color saturation (particularly in blues and greens). Clouds will pop, trees will stand out, and images will generally appear richer.

Polarization dangers

Polarization is a great effect, but it can be overused. At high altitudes, where there is very little atmosphere to help scatter the light – or even at sea level on a crisp, clear day. Too much polarization can cause the sky to go navy blue (or close to black). Not good.

Also, because the polarizer is quite dense, it can cause your wide-angle shots to experience dark edges if you aren’t careful. To combat this, you can get a “thin” polarizer, which are more expensive, but will help remedy this vignetting problem.

Finally, make sure that you use a circular polarizer with a Digital SLR, as a linear polarizer could cause trouble with the autofocus sensor in your camera.

Using a Polarizer

The polarizer effect only functions when it is rotated in proper relation to the scene you are shooting. You’ll still get the benefit of increased contrast and saturation without doing so, but the reduction of glare can only be achieved this way.

Circular polarizers rotate, and when you rotate one, you’ll see stuff happening in your viewfinder. What you’re doing is lining up the etching on the filter with the stray waves of light. What you’re looking for is a reduction in glare off surfaces, and for an increase in the contrast between sky and clouds. Metering will all be handled in-camera with the filter attached by the camera’s internal metering system.

Bear in mind that when some lenses focus, the end element (which the filter is attached to) also rotate, so you will need to use a little forethought if this is the case, by focusing first, polarizing after.

Have fun!

Digital photography has certainly revolutionized a lot of the typical (read: film) photography workflow, but certain questions keep popping up. I’m often asked by photographers what the best method is for shooting in black and white.

While some cameras do have a black and white conversion mode, allowing you to shoot that way in-camera, it’s usually not the best choice. First of all – who knows what pictures you want in B&W and which you want in color at the time you shoot? Typically (or ideally) you want to make that decision after the fact, when you’ve had time to mentally process the image. Second, the conversion in-camera is essentially just a desaturation of the image, which is not the best way to get a good quality monochrome image. It will remove all the color, but those “greys” that result from desaturating usually have a lack of contrast or tonal panache.

Getting great black and whites is a matter of some subtle manipulation, and Adobe Lightroom is one of the best (and most straight forward) pieces of software with which to achieve this. I just love Lightroom.

Martin Evening is a studio and fashion photographer who works closely with Adobe, and over at the Lightroom News blog he explains (in video) how to best convert a color image to black and white. Check it out!

If you’re a photographer, you’ve encountered infrared photography at some point. In the days of film, IR was done using specialty film and a filter. These days, most of us don’t use our film cameras much, if we still have them. The digital SLR has replaced them, for ease of use and generally improved clarity. But what if you want to shoot IR on your digital SLR?

What’s so special about IR? At first glance, a picture taken in infrared may look similar to any other black and white photograph. When you start looking closer, you start noticing the differences, however. Objects which are bright in visible light (like sky) look dark in IR, while some which are normally dark (like green leaves and grass) take on a ghostly glow.

For this to work, you need a digital SLR that is not overly sensitive to IR. That is, one that won’t block infrared light. Unfortunately for us, most SLR’s these days have an IR filter in place over the actual CCD sensor to phase out infrared light, since IR can adversely effect the clarity of images under normal circumstances.

Some older model SLRs are less obstructive, and you can test to see what kind of results you get with your own… but if you’re serious about your IR, you will mostly want to take this filter out of the camera by force. Taking out your IR filter means that your camera will, in essence, become an IR camera… so be sure you want to do this. It’s likely a good idea to only do this on a backup or older second camera if you have one.

Be advised that these modifications are not manufacturer recommended and can void your warranty (if one exists) should something go wrong. While these are excellent DIY tutorials (mostly provided by LifePixel.com), use them at your own risk. If you’re not comfortable doing this yourself, LifePixel also offers a service to convert for you, for a fee.

Nikon

D70/D70s
D50
D100
D1X

Canon

5D
10D
20D
Rebel XT
Rebel

A few other models and brands can be found here.

After this is done, you’ll need a filter on the camera that can filter out the visible red light. Tiffen, B&W, and Hoya all make filters for the above digital SLR’s. Hoya tends to be the preferred Nikon brand, as they make filters in thread sizes that fit most Nikkor lenses. You’ll need something deep red. The Hoya 72 filter is widely acknowledged as one of the best filters for IR photography. For smaller cameras (like Nikon Coolpix cameras) you’ll want a Wratten or Harrison & Harrison filter. Check your filter size in your camera literature.

1) You will need a Tripod. Because of the lack of visible light, the shutter speeds you’re going to get will be longer than usual (in the seconds range).
2) Because the filter is so dense, you’ll likely need to focus first, then carefully (as not to move the camera) attach the filter.
3) You’ll also want to set a medium high ISO on the camera (400 or 800). 4) Lastly, you’ll need to set the exposure. Typically, you’ll do this in a manual mode. Try to keep your shutter speeds below 5 seconds (to minimize ISO generated noise) and then adjust your aperture as needed.

Though it’s not necessary (since you can convert later), if you have a black and white shooting mode on the camera, use it! It will help you to evaluate the exposure while shooting.

If you want to see some examples of fine Infrared photography, check the Flickr Infrared Group, which has some excellent pictures.