This video is part of our Intro to Photography series, where we break down some of the fundamental concepts of the image-making process. You can find a written version below.
Intro to Exposure
What is Exposure?
Exposure is perhaps the most important concept in photography. The word ‘photography’ is derived from words meaning “drawing with light,” so the amount of light your camera is exposed to is absolutely fundamental to the process.
What defines exposure?
Three factors define how much light your camera sees, and they’re not necessarily the three you might expect:
- Aperture value, or size of the hole through which your camera sees the scene
- Shutter speed, or how long the shutter stays open to let light in
- The amount of light in your scene
These three factors determine how much light hits your sensor. And that’s arguably the most significant thing that determines image quality: how much light you captured to describe the scene. That’s not quite the end of the story, though.
What about ISO?
Your camera also has a setting called ‘ISO’ that determines how light or dark your final image looks. So if you’re shooting in low light, you can increase the ISO to make the image look lighter. But be aware that changing ISO doesn’t increase the amount of light you captured: it just tries to make up for the fact you couldn’t capture more.
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| Pentax K-3 Mark III | Pentax 15mm F4 ED AL | ISO 32000 | 1/30 sec | F8 Edited in Adobe Camera Raw with noise reduction left to default Photo: Carey Rose |
As light levels fall, your images will get noisier, because of the lack of light. ISO can’t really help with that, but it’s not the thing causing the noise.
Shutter speed and aperture each have an impact on what the final image looks like. Once you understand those impacts, you can learn the balancing act required to get as much exposure as you can, then use ISO to try to make up the difference.
Intro to Exposure
Our DPREVIEW Tribute:
After nearly 25 years of operation, DPReview closed on 10 April 2023. This difficult decision was part of the annual operating plan review that parent company, Amazon, shared earlier this year.
Over the course of 25 years, DP Review built up a reputation as being one of the most informative places to go for information about that new camera or lens you’re after. DP Review began as an independent reviews site based in the UK in 1998, the brainchild of Philip and Joanna Askey, but it was eventually purchased by Amazon in 2007 and relocated over to Seattle in the USA in 2010.
Cheers DPReview – thanks for the great work and content that guided photographers, videographers and techno junkies the world over!