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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A splash of color

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12-8-13 Acadia1At first glance, there wasn’t much color inside the dark cave, but as my eyes adjusted to the low light raking in from the right-hand side of the entrance, a range of earthy-toned blacks, browns and subtle greens could be seen on the algae-covered and very slippery rocks. And then there was the pink-colored bottom of one the tidal pools – that’s right, pink.

I tried hard to get an exposure that looked somewhat natural – several frames were bracketed and blended for this image – but no matter what I did, I couldn’t quite convey just how interesting I found the pink, sandy bottom of the tidal pool in the foreground to be. There wasn’t a lot of light in the cave, and in this type of situation the camera has a hard time capturing the range between the darkest and lightest parts of such a scene. In person, our eyes can adjust on the fly, allowing us to see the detail in the brighter clouds AND the wave-sculpted, jagged sides of the cave AND the darker underwater life in the tidal pools.

However, the mechanical nature of the camera means that it cannot make the gradual adjustments that our eyes can, and it can have difficulty creating an evenly balanced exposure of such a scene. In my next blog post, I will describe how I used several exposures to create one image that incorporates the range of light I witnessed, while at the same time hopefully maintaining a natural look.