A range of light…

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As promised, here’s a low-tech description of a process I sometimes use to capture a wider amount of dynamic range than the camera is typically capable of handling – all within one photograph. Inside a dark cave like this looking out at a bright sky can present significant challenges when it comes to creating a correctly exposed, relatively natural-looking single exposure, and although this is a pretty extreme example, sunrise and sunset scenes can present similar challenges. Here’s a brief description of a process I sometimes use when dealing with a high amount of dynamic range within a scene.

12-8-13 Acadia1

I know I am somewhat over-simplifying things here, but what the hey, there’s nothing wrong with simple. In scenes where there is a high degree of dynamic range, we can use the camera to basically record:

a) an image with a correctly exposed foreground but a bright, overexposed white blob where the sky is located.

b) a correctly exposed view of the sky through the cave entrance with everything else in the scene jet black and devoid of any detail (actually quite cool and a composition that I made).

c) you can settle for something that averages out the need to expose for both the brighter sky and the darker recesses of the cave at the same time, though in this case, I believe that nothing more than a so-so result is produced.

In another scene where the light is more even, such a single exposure might work very well, but in a scene like this where there is a significant degree of dynamic range, my personal choice to get a relatively balanced overall exposure is to shoot several identical frames while the camera is on a secure tripod and then blend them using the puter. By keeping the size of the aperture the same in each bracketed shot – but adjusting the length of time the shutter is open – I can obtain several versions of the same scene. Stating the obvious here… but depending on how long the shutter is open for, some exposures will be darker, and some will be lighter. Then, taking parts of each frame I think best represent what my eyes could see – all in the name of working around the limitations of the camera and trying to create a fairly accurate representation of what the scene looked like – I combine them into one image.

12-9-13 blend

Just for giggles, here are three typical exposures that each captured a different range of the light in the cave more accurately. All shot at f11, iso 100 and at 17mm using a 17-40mm lens, from left to right, the length of the exposures were 1/100th of a second, half a second, and then 2.5 seconds. As you can see, the shortest exposure (1/100th sec), captured the early morning sky fairly accurately, but the rest of the scene is completely underexposed (not necessarily a bad thing, but my eyes could definitely see more foreground detail than is evident in that one exposure). The 2.5 second exposure captures just a little bit of the spectacular pink color my eyes could see in the foreground tidal pool, but the light streaming in through the cave entrance is totally over-exposed and, in this case, I don’t think all that pleasing. In the middle exposure (0.5 seconds), some of the detail in the rocks on the side of the cave is useful, but overall you end up with an exposure which doesn’t do justice to either the brighter or darker parts of the scene.

So… rather than settling for any one of the above exposures as a final image, one potential solution is to take what you need from each, add a little special sauce, and you’ll end up with a blended image like you see at the top of this post. Imagine layering the three versions of the scene shown here on top of each other, and then erasing the bits from each version that are either under or over exposed. I use Photoshop, but any photo-editing software that has “layers” will allow you the precise control to do this.

And then of course, there’s black and white… happy New Year!

Acadia sea cave2
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8 thoughts on “A range of light…

    • David Patterson

      Thanks Nate. In an attempt to try and replicate what my eyes could see, I’m hoping to use this type of technique to keep the processed scene relatively realistic.

      • That’s one thing about HDR, one has to be careful not to go too crazy because it can get over done relatively quickly. But, when done properly (as you most definitely have with this photograph!) it is a fantastic technique for exactly what you say– to make the scene as close to what our eyes have seen that the camera sensor couldn’t capture. Since learning HDR techniques, I’ve been almost obsessed with seeking out scenes that almost require the technique. Its really quite fun to work with actually.

        • David Patterson

          Nate… when dealing with scenes with a high degree of dynamic range, I try to keep things as realistic as possible. Most of my landscape work is carried out pre-dawn, or at least right around when the sun comes up – which means there are likely to be significant exposure needs between a darker foreground waiting to be illuminated, and a quickly brightening sky. I’ll usually bracket by a couple of stops, and most of my landscapes are a simple gradient mask blend of two exposures. I don’t have the patience to fiddle with filters when in the field, and since I find the bracketing and blending process is relatively simple to achieve after the fact, it’s my go-to in this type of situation. I also find it to be a pretty accurate way to represent what the scene looked like, and unlike many people, I too find it fun to experiment with 🙂

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