Today’s Post by Joe Farace
More and more cameras are offering higher ISO setting. The new full-frame Pentax K-1 Mark II that I tested for Shutterbug has a high ISO setting of 819,200. What did I think of it? You’ll have to read the review to find out.
Along with the good news comes the bad. Noise in digital photographs is the visual equivalent of static in radio signals and most digital cameras add some noise to images for slots of reasons. Digital noise has many causes: Dark noise is produced by heat from the camera’s sensor during capture. The dark current produced is collected along with the light passing through the lens. Random noise is created by fluctuations within the camera’s circuitry or electromagnetic waves outside the camera.
Signal noise is caused by fluctuations in the distribution of how light strikes a sensor. You’ll sometimes hear the term signal-to-noise-ratio ratio, which is a measure of signal strength relative to background noise. Amplified noise is caused by high ISO speeds and is the digital equivalent of “pushing” film to achieve greater light sensitivity. Then there’s accumulative noise, which is caused by using slow shutter speeds.
How I made this shot: Some nighttime photography involves trial and error. Camera used was a Canon EOS 50D with EF28-135mm f/3.5-5.6 IS USM lens. While photographing cruise night on the main drag on Escondido California, I kicked the camera’s ISO setting up to 800, set the camera in Aperture Priority mode and just lived with the resulting 0.3 sec exposure because I was more concerned about the mood than capturing these street rods in sharp focus. I experimented with Exposure Compensation and increased this shot by one-thirds stop but it was still slightly underexposed.
Along with photographer Barry Staver, I’m co-author of Better Available Light Digital Photography that’s now out-of-print but new copies are available from Amazon for $21.88 with used copies selling for giveaway prices ($4.00) as I write this.