For a long time I have been shooting to the right hand side of the histogram when shooting RAW files with DSLR cameras and in the process I am technically over exposing my photos by about 1/2 to 2/3 of a stop. What surprised me recently is that a couple of experienced shooters I know didn’t really know anything about this technique when I mentioned it to them and so I realized perhaps there a lot of people out there shooting with DSLR cameras who don’t know to shoot this way either when really they should.
The main reason for shooting like this is to bring out more shadow detail and color and to prevent digital noise from occurring in the darker/shadow areas of the photo as you lighten/brighten your pictures when post processing. Many people however would assume shooting at a slightly overexposed level will result in the blowing out and loss of highlight detail in the process. Now that is not the case if you do it right. In fact, Photoshop is often able to recover lost highlight detail now from RAW files with their new “highlight” recovery slider featured in their RAW processing plugin; Camera RAW.
So, lets talk a bit of the science behind why I shoot many of my photos technically overexposed. The term “expose to the right” simply refers to the histogram associated with taking photographs with digital cameras. Typically, for a shot to be correctly exposed, we were taught to aim for an even distribution of tones throughout the histogram (a graph which shows the range of highlight to shadow detail in a digital photo) with the peaks of the graph weighted in the middle, and then tapering off at the left and right edges. The tapering off at the edges means you avoid too many absolute black or absolute white pixels in your photo, which is technically a loss of information. So you aim to end up with a histogram that sort of looks like the shape of an upside down letter “U”.
But when ‘exposing to the right’ the idea is to push the normally center weighted area of the histogram about 1/5th over to the right thus, technically overexposing the image a bit, but not so much as to end up clipping/losing any highlight detail. This means you don’t end up with a histogram that is over weighted on the right hand edge of the graph. The benefit of shooting this way though is that the resulting file, when post processed back to the correct exposure level, will contain more tonal information and less noise in the shadow areas (which are the areas on the left-hand side of the histogram). This maximizes your final post-processed image quality.
The CCD or CMOS sensors found in most digital cameras can capture roughly 7 stops of dynamic range (which refers to the range of highlights to shadows in a photo and everything in between). That is a lot if you consider the dynamic range of negative film used to be about half of that and positive slide film was lucky to have 2 stops of dynamic range. So DSLR cameras produce 12-bit RAW image files and are capable of recording 4096 tonal levels in each of the three color channels; red/green/blue. The ability to record such a wide range of tones should ensure a smooth transition between the vast number of tones within the resulting image if the image is captured within range of the correct exposure level.
Often people even shoot by under exposing their images a bit as they are worried about blowing out highlights. But if you underexpose the shot and then correct the exposure during post processing to bring out more detail in the shadows, then the tonal transitions in the darker areas will not be as smooth. Plus you have a risk of degrading your overall image quality. However, if you technically overexpose your image a bit by shooting with the histogram weighted more to the right of the center then you will capture much more digital information which results in much higher image quality as you balance the exposure of the image during post processing.
A simple way of demonstrating the difference in the amount of tonal detail captured by a digital camera is to shoot two images of the same scene. Shoot one slightly underexposed and one slightly overexposed and compare the file sizes of the two resulting RAW files. The overexposed RAW file will be larger than the underexposed file as it contains more data. So this further proves the scientific fact that there is more digital information captured in a slightly overexposed image as opposed to a slightly underexposed image.
Images that have been exposed to the right though will need some additional post processing to correct the final picture, but, as you can see, a bit of extra planning when you shoot by over exposing a bit, and some extra steps to correct the image during post processing, can result in photos with reduced image degradation in the darker areas.
It is not a technique that is applicable to all types of photography across the board though as there is a risk of losing highlights if care is not taken when setting the exposure on your camera. Especially if you are in a very high contrast lighting situation where the frame of the shot contains areas of very bright highlights and other areas of deep, dark shadows, the two of which are more than about 5 stops of exposure apart. Overexposing in this situation could in this case result in a loss of highlight data. But exposing to the right works really well in situations when photographing in a controlled environment, for example, when shooting landscapes. Using graduated filters to darken the bright areas of a frame can also help to further ensure that all highlights are contained within the dynamic range the sensor is capable of capturing and don’t get blown out as you start to aim to lightly overexpose the capture by shooting to the right.
This method of shooting carries with it a number of important lessons. The most important thing is that if you do not use the right-hand fifth of the histogram for recording a greater percentage of your image then you are in fact wasting half of the available recording range of your camera.
The other simple lesson to be learned from this is that you should shoot your exposures so that the histogram is pushed more over to the right, but not to the point that the highlights that are at the right-hand end of the histogram are getting clipped and completely blown out. Highlights being blown out when shooting can also be seen by using the highlight alert setting on your DSLR camera which will flash in areas that are being clipped and provide an alert on the camera’s review screen. If your DSLR camera has this function it can be very useful for helping you to decide how far overexposed you can safely shoot without losing digital information.
Now when you look at a RAW image “shot to the right” in your favorite RAW processing software, like Camera RAW for example, the image will likely appear to be too bright at first. That’s OK though. Just use the available sliders to change the exposure level, highlights, whites, and contrast so that the data is spread out more evenly and the image looks “right” to your eyes. This will accomplish a number of things. The first is that it will maximize the full dynamic range of the image. The second is that it will minimize the visibility of digital noise that potentially occurs in the darker regions of an underexposed image.
Give shooting to the right a try. You will probably find your images start visually having better color pop and overall vibrancy than before once you adjust them in post processing to the brightness levels that they should be viewed at.
I just did some unscientific tests…and I’ve come to realize that I’ve been underexposing and not really getting the best image from my camera as I could. Using a cropped sensor, the issue is probably worse! Geeeez! Well…now I know. Always learning new things. Thanks for this article.