Experiment series: HDR
What is HDR
HDR stands for High Dynamic Range. But what do we call dynamic range? It’s the amount of details we can get between the darkest and the brightest part of an image. We usually measure this range in f-stops. To give you an idea, DSLRs can capture between 10 to 14 stops.The human eye can see around 24 stops (this is more a comparison value as our eyes do not work exactly the same way cameras do).
Ok but how does it affect your photos? Let’s say you’re taking a photo outside in a bright sunny day with strong shadows. You will have to choose between capturing details in the brightest parts or the darkest parts but you won’t get both at the same time. And that’s when the HDR technique comes in. The idea is pretty simple. Underexpose your photo and you only get details in the highlights. Overexpose it and you only get details in the shadows. But then if you merge those 2 shots in post with specific applications, you end up with one composition that has both details in the highlights AND shadows and thus getting closer to what you could actually see with you own eyes.
Now, for an HDR you normally need at least 3 images: an underexposed, a properly exposed and an overexposed image. Of course, If you really want to capture as much details as possible you can take more than 3 photos!
The technical side
For the photos you see below, I shot between 6 to 8 times the same photo with half a stop of difference between each ( -2 / -1.5 / -1 / -0.5 / 0 / +0.5 / +1 / +2 ). I then used photoshop CS6 to merge them all together.
To illustrate my saying. In the screenshot below, you have on the left side an underexposed photo. You can’t see the details in the rocks but you can see the gradient in the sky. On the right side, you have a overexposed photo where you can see the details in the rocks but the sky is now just plain white. When combining them together you get the end result that follows (there were 8 shots for this HDR) . Bear in mind that I shot RAW which is pretty flat. So I had to boost the colours afterwards to get the result you see here.
The creative side
Because you’re shooting many times the same frame it is important that they all match. Otherwise you’ll end up with a “ghosting” effect. Avoid any composition where there could be motion (or use long exposures) . Landscape and architectures are perhaps the easiest to photograph in HDR. Same goes for you. If you move between two shots, the images won’t matches and it will be harder to work in post. So use a tripod! And for long exposure photos, I would even recommend a remote control.
When I first experimented with HDR, I was only taking 3 shots with 2 stops difference between each. I ended up with photos that were way too drastic which gave them an unrealistic look. I learnt that the more subtle it is the more pleasing to the eyes it will be. So shoot more exposures with less differences. (instead of 3 shot with 2 stops, try 6 shots with 0.5 stops).
Post processing is not that easy either! And I’m definitely still learning myself. If you look closely at that the edges of some of the photos, you’ll see that they’re not always perfectly blended together which gives you this “glowing look”. When merging the photos try to get something as flat as possible first and then edit your photo to your liking (not while merging). I don’t know if it’s the best way to do it, but that’s how I personally got better results.