“Low light” is a relative concept. Landscape and architectural photographers work with light levels far lower than those available to theater and dance photographers, but the challenge is similar: we need to find the right combination of ISO, shutter speed, and aperture to produce high quality images. I need fast shutter speeds to freeze action, so I need a lot more light than someone photographing Half-Dome on a windless dawn.
As some of you know, I pine for the Nikon D3s, aka “The Lord of Darkness,” but I recently got a pleasant reminder that there are less expensive options for better low light results – and some of them are already in my camera bag.
Last week I photographed a dress rehearsal of the Ojai Art Center Theater production of Sylvia. Because there was a test audience, I did not want to roam the theater and distract them, so I settled into the second row. I shot most of the performance with my Nikon 17-55 f/2.8 zoom lens, but every now and then, I used my ancient 85mm f/1.8. And, as usual, I managed to be surprised at the superior quality of the images made with the 85. Will I ever learn?
The 17-55 f/2.8 is a very high quality lens, and it is considered a fast lens. But the f/1.8 lens is much faster, allowing more than twice the amount of light into the camera. This allows the camera to focus better, because it can see better. It also allows the sensor to record at lower ISO values, which improves dynamic range and reduces noise/grain.
Images captured with the faster lens are not necessarily sharper because the lens is sharper; they are sharper because I did not have to apply noise reduction software, which minimizes grain by subtly blurring the image.
There are other trade-offs, of course. Shooting from a fixed location, one gives up a zoom’s focal length flexibility for the faster aperture of a fixed focal length lens. I don’t like to change lenses frequently, especially in the dark, but next time I’ll probably bring my faster prime lenses and leave the slower zooms at home. I’m not particularly unhappy with the pictures from the 17-55, and they serve their purpose, but images lose a lot of sharpness by the time a newspaper gets through with them, so I want to start with the sharpest photos I can make.