what is expose to the right?
If you are not using this method of exposure and want to get the ultimate image quality from your digital camera, you should read on. The process of making the optimum exposure with a digital camera is different from a film camera, especially when you are shooting in RAW. Back in the days when we were all shooting slide film, we were taught to be very careful not to overexpose our photographs – “do not blow out the highlights!” Although this advice was less important when using negative film (B&W, or color) given the increased latitude of those films, but avoiding overexposure was still important since it made pictures more difficult to print.
With film we relied on the camera’s exposure meter (along with bracketing and experience!) to make a good exposure. Now, with digital cameras, we have that amazing histogram (and LCD image) on the back of the camera that I hope you all are using. We can see immediately if we have exposure problems by checking to see if any clipping of the highlights or shadows has occurred. Note: You should have your camera’s overexposure warning system turned ON so that you will see “blinkies” on the LCD screen if areas of the picture are blown out.
If you are shooting in any mode other than manual exposure, the camera will provide a “normal” exposure, assuming you have not dialed in any exposure compensation. This should give you a good exposure, but probably not an optimum digital exposure. By optimum, I mean an exposure that will capture the maximum amount of digital information for the scene without blowing out the highlights. Without getting too technical, let me just say that digital capture is a linear process (as opposed to film which is non-linear) and most of the information is captured in the brightest areas, with very little being captured in the darker areas. Lack of light captured in the darker areas means that the signal-to-noise ratio is low in those areas and this equates to noise in the image. If you have ever tried to lighten darker areas of digital image, you know how noise tends to pop out.
To optimize your exposure, here is what you do: Take a test shot of your subject and then adjust your exposure to push the histogram to the right by moderately overexposing your image, being careful not to clip the highlights (you can ignore specular highlights, like the sun). For most scenes, I generally have my camera’s exposure compensation set to +1/3 or +2/3 stops to push the exposure toward the right. The key is to pay attention to the histogram and add exposure when needed. Some low contrast, bright scenes may require you to push it by +1 or +2 stops to get the exposure to the right edge of the histogram. Note that by using this method, you are essentially using a lower ISO to capture the image, since longer shutter speeds and/or wider apertures are required. The photo above was exposed with a +1.33 compensation, pushing the histogram to the right. With no compensation, the camera would have under exposed the image due to the large amount of bright snow in the picture.
Keep in mind that some images made using the exposed-to-the-right method will look over-exposed on the camera LCD screen and will require adjustments in post processing to make a perfect looking image. However, making these adjustments to RAW images will provide you with the most digital information possible without any loss. And it will help minimize noise in the dark areas since the signal-to-noise ratio was as high as possible for that particular scene.
If you shoot only in JPEG format, exposing-to-the-right might not make sense for you especially if your intent is to post images online as soon as you make the picture, or if you do not wish to take the time and effort to post process your images. In those situations, when shooting in JPEG, making exposures based on the camera’s normal exposure system may be the best bet to get a good looking picture. Just keep in mind that this will not give you the ultimate image quality. Although digital sensors and noise reducing software is now incredibly good, I still use expose-to-the-right because I know this method will produce the ultimate image quality and give me the most latitude in making adjustments in post processing. Exposing-to-the-right might be right for you too!
One last note, I don’t know who to attribute this quote to, but I have always liked it:
“Amateurs worry about equipment, professionals worry about time, masters worry about light.”