the last word

Bird and wildlife photographers are concerned with the reach of a camera and lens setup. Let’s define reach as the number of pixels per degree. If you’re a bird photographer, more is generally better. Here’s how to calculate reach given the focal length of the lens and the pixel pitch of the sensor. Let’s define… [Read More]

When you increase the exposure time in a digital camera, you expect to collect more signal. But what happens to the noise? The answer depends on the source of the noise. Understanding how each one scales with exposure time helps you optimize your imaging strategy, especially in low-light or long-exposure situations. Let’s look at the… [Read More]

In low-light or long-exposure photography, one of the most persistent sources of unwanted signal is dark current: thermally generated electrons that accumulate even in total darkness. Unlike read noise, which is largely constant from frame to frame, dark current grows with exposure time and varies from pixel to pixel. Dark current is the rate at… [Read More]

Cooling a CMOS sensor reduces noise. But which noise? By how much? And is it worth the effort for your application? Let’s break it down by examining what cooling affects — and what it doesn’t — in the readout chain. What Do We Mean by “Read Noise”? Read noise includes all non-random and random noise… [Read More]