Monday, February 25, 2008

Why Shoot With Ambient Light?


Although this photo doesn't say much in terms of subject matter, it speaks volumes when it comes to why I prefer to shoot many images with ambient light only. The Field Museum has relatively dark hallways and this is a good example of that. You can see that the light to the right of the railing is much brighter than this hallway light. This opens up to the main floor area downstairs.

Click on the image to take a close look at the how well you can see everything... from the foreground to the background, everything is well lit. Look down the hall and check out the lighting way off in the distance.

With a flash, only the areas in the foreground would be properly exposed. Everything in the background would be dark.

Often, I see people taking photos with their point and shoot cameras at places like the Field Museum and their flash is always on. In general if all you are interested in is to see the objects immediately in front of you, a flash is your best bet. The people won't blur (any motion from them will freeze because the light is on and then off so quickly and the digital sensor records the image in a split second) but all of the background will be dark. Maybe that's ok for some shots. But if you want to take a shot like this... down the entire hall and have everything lit up, the only way to do it is to shoot with the light that's already there.

The Fuji S5 Pro camera is great in this regard. You can make the sensor really sensitive to light and so that means a high ISO setting. By doing this, you can take a photo so that the shutter speed is faster than if you were to use a low ISO setting. This means less camera shake and people in the scene will be captured without (or with very little) motion blur from the camera. Opening up the aperture of the lens and letting a lot of light in helps too. And the dynamic range of the Fuji camera is quite evident here too. Dark areas of the scene are rendered just as clearly as brighter areas.

This image was shot with an ISO setting of 1600 and the aperture of the lens set at f 2.8. The camera chose a shutter speed of 1/45 second. Since the focal length was set to 18mm, handholding a camera with this wide angle means that very little camera shake is going to record on the image sensor. In theory, you should be able to handhold a camera at the reciprical of the focal length of your lens without camera shake. So at 18mm, I should be able to shoot a relatively shake-free image down to 1/18 second for a shutter speed but factoring in the 1.5 crop factor for the digital sensor in this camera, 1/18 second becomes 1/27 second. So this shot taken at 1/45 second is no problem at all to avoid camera shake. Of course at 1/45 second, should people in the scene move, they will blur. But at least it's not from the camera being shaken! You can see that the man in the foreground is blurred because he was walking. But the rest of the image that is stationary like the walls and displays are not blurred.

A rather boring photo in terms of subject matter, but a very telling photo in terms of touting the benefits of ambient light.

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