Picture This: Sensors and Sensitivity
Technical advances enable cameras to better capture the drama of low-light photography.
By Earl Nottingham
From professional digital still and video cameras to the smallest camera phone, the ability to create a quality image continues to improve in quantum leaps with each new product rollout. Most often, these leaps are a result of technical advances to the heart of every digital camera — the sensor — and in the search for the latest and greatest camera, consumers often look for the camera containing a sensor with the highest number of megapixels, believing that more is better.
While this is true to a degree, two other characteristics — sensor size and sensitivity — should be a consideration when choosing a camera, not just the total number of megapixels.
As a rule, bigger is indeed better when it comes to the overall dimensions of a sensor because a bigger sensor not only provides more pixels, but bigger pixels, which more efficiently gather light and sample color. Sensors can range in size from one-quarter to three-quarters of an inch for camera phones and point-and-shoot cameras to almost 1½ inches for full-frame digital SLR cameras (see illustration). The impressive video quality and compact size of the larger sensor cameras have led to the use of these digital SLRs in the movie industry, replacing video cameras in some filming situations.
However, of all the improvements to come down the pike, perhaps the most notable are not the increases in sensor size but the innovations in increasing a sensor’s ability to gather light in low-light situations and to record a wider range of light (dynamic range). Much-improved sensor processors now allow the photographer to get detailed low-light images by allowing shots at high ISO levels that previously generated unflattering digital “noise,” or graininess, in an image. The ISO level indicates the camera’s sensitivity to light.
Depending on the camera manufacturer, you will see maximum extended sensitivities in the range of ISO 102,000! What a difference from the day when we thought that ISO 400 was fast. Although images can be made up to ISO 102,000, the digital noise level at that range can appear very grainy. Of course, each photographer will have his or her idea of what is aesthetically acceptable. Images that I have seen made with ISOs from 6,000-12,000 look very good and are comparable to ones previously shot in the 1,600-3,200 range.
The payoff for the photographer is that images that were previously unattainable because of low light can now be made thanks to the improvements in the sensors and their processors. Landscapes that once could be photographed by moonlight can now be captured by starlight. Portraits can now be made with just a few candles.
Obviously, the more professional DSLRs will perform better than cheaper cameras in low-light situations, but even inexpensive point-and-shoot cameras should produce outstanding results. For photographers of all skill levels, it opens a whole new way of seeing things.
Please send questions and comments to Earl at earl.nottingham@tpwd.state.tx.us.
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