Many of you have probably heard of the technique of exposing to the right when shooting digital. The reason is that most of the tonal information is recorded in the 4 stops on the right side of the histogram. In fact half of all of the tonal information is recorded in the last stop on the right side of the histogram.
Basically for each stop you go to the left, you lose half as much tonal information as the previous stop had. With that in mind, you can see why you want to adjust your exposure so that your highlights are all the way to the right side of the histogram. The idea is to open up the highlights as much as you can without blowing them out(at least what you don’t want blown out). This puts as much of the tonal information on the right half of the histogram as you can get which means that your RAW file has as much data in it as it can get. Or does it?
Until the other night that’s what I thought and how I’d been basing my exposures. After going to a workshop at my local camera club, I found out that this isn’t completely correct. As it turns out with most, if not all, DSLRs you can actually push your highlights beyond the right side of the histogram and end up with images that are better in quality. I know this sounds crazy, but it’s true.
So how far can you push your highlights? That of course will depend on your camera, but you can likely push them about 2 full stops to the right of the histogram. What you’ll need to do is some experimenting with your camera to see just how far you can go. You’ll want to find a scene with a pretty wide dynamic range so you can really see the difference, particularly in the shadows. You’ll want to spot meter your highlights that you want to retain full detail and then adjust your exposure until you see the highlights right up to the right side of the histogram. It’s best to do this in manual mode. And unless you have a histogram in your viewfinder, you’ll need to use Live View as well. Finally you’ll need to shoot RAW and not jpeg. Take one photo like that and then open up one stop at a time (you can do half or third stops if you want as well to fine tune this) and take additional photos each time.
Once you’ve done that, bring them into whatever RAW editing program you use and then for the photos that you shot after opening up the exposure, go ahead and bring them each down the same amount you opened up. For the shot at +1 for example, use the exposure slider to bring that image down 1 stop. This makes each photo equal in exposure so you can compare them. Now by looking at them at 100%, you should see a noticeable difference in image quality. The photos where you pushed the highlights past the right side of the histogram will have smoother tones especially in the shadows. Go ahead and open up the shadows on each one to +100 and you should really see a difference. This is because you’ve captured more tonal information by pushing your histogram further to the right and the fact that RAW files have a lot of latitude when pulling back highlights and opening up shadows. You’ll also notice that the file sizes are larger as you do this until you reach the point where you are actually blowing out your highlights. At that point you’ll see the file size go down as there is less tonal information to capture as you begin to blow out your highlights.
Here are two examples that I took yesterday. These are 100% crops and the only thing I did was open up the shadows on both to +100 and drop down the exposure on the 2nd one by 2 stops(this was my +2 exposure). I found that on my Canon 7D MK II I can push my highlights 2 full stops and get much better quality images. I tied 1/3rd stops after that and noticed that 2 and 2 1/3 were almost the same. At + 2 1/3 I noticed that my highlights started to get a little muddy, so I’ll stick with +2.
As you can see in my examples, pushing your highlights beyond the right side of the histogram actually produces better quality images. Here are 100% crops showing the highlights. You can see the 2nd one shot at +2 still has the same amount of detail in the highlights as the first one, but has smoother tones.
I do want to point out that this really only applies to shooting RAW. Jpegs just don’t have the latitude to be able to pull back you highlights and recover the detail. For jpegs you’d want to keep you highlights just to the right side of the histogram. It’s going to feel weird since according to your LCD it’s going to look like you’re overexposing your images, but as you can see, you’ll actually end up with better quality images.
I’d love to hear from anyone who gives this a try.