Continuing the wildlife theme from yesterday, today’s post is a photograph from a visit to Monterey Bay Aquarium in late 2007. Aquariums are challenging photographic environments so it’s rewarding to get any decent shots from a visit to one. As well as being a reasonably decent shot, this photograph is an example of why it’s a good idea to take control of the exposure away from your camera and shoot in manual mode.
The challenge of photographing in an aquarium is two-fold. Firstly, aquariums tend to be low-light environments – I guess fish aren’t used to bright daylight. A solution might be to use flash. Which brings us to the second challenge. There’s a lot of glass in there. And glass reflects flash light.
I often see people take shots with their compact digital cameras pointing straight at the glass, with the camera in automatic mode and as they press the shutter, the camera does what it expects is the right thing to do – it meters the scene and determines that it is dark, it decides to brighten it with some flash, and as the shutter opens, it fires the flash straight at the glass in front of the camera. All that flash light bounces straight back into the lens, and the image that comes up on the back of the screen is only fit for deletion. A little tip if you’re photographing through glass in a dark environment – turn off the flash, hold the camera right up against the glass, and try to keep it as steady as possible. This doesn’t just apply to aquariums – I’ve seen it happen in the zoo too.
For this photo I followed my own advice and kept the flash turned off. The camera was in manual exposure mode, and I used a wide aperture to get the shutter speed as high as possible. To assist this I had pushed the ISO all the way to 1600 – very high on the D50, which accounts for some noise in the final shot.
The shutter speed ended up being 1/40s which is still prone to some camera shake, so I had the camera right up against the glass to keep it stabilised. Of course at 1/40s, keeping the camera steady is all well and good, but if the subjects are moving quickly you’ll still get some motion blur. Sometimes this is what you want, sometimes it is not. Here it didn’t become an issue as jelly fish move in a slow pulsating manner, and I could time the exposure to get them when most of them were moving at their slowest.
The final image is actually technically underexposed. I say this because, if I look at the histogram for the shot (which plots the number of pixels of every shade from pure black to pure white, there are very little in the upper quarter of the scale. As a rule of thumb, a properly exposed image will have both pure black and pure white, but only a minimal number of pixels of each, with the bulk in the middle of the range. In any automatic mode the camera sets the exposure so this is the case. Sometimes however a scene won’t have pure black or pure white, and this is certainly true here. It’s naturally a dark scene, and so the viewer wouldn’t expect a pure white area of the photo. So while the image is technically not properly exposed, it is, for this subject matter at least, the correct exposure. The difference is subtle, but important, and a good reason for shooting in manual modes.
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