Don’t Be Afraid Of High ISO on Modern DSLR Cameras
This article is written by Andrew S Gibson, author of Understanding Exposure – a guide to controlling your camera to achieve perfect light exposures.
As the internet grows and grows, photography tutorials are becoming more and more abundant. All that information can be a good thing, but it can also create problems as it sometimes has the magical effect of turning one’s opinion to fact over time. Read around about digital photography and you will come across the ‘stock’ advice that some people give. Over time, this gets repeated until it becomes part of the conventional wisdom about photography.
One of these is in relation to ISO. The usual advice is to use the lowest ISO possible when you take a photo. There’s a good reason for this, as the image quality is always higher at lower ISOs than higher ones. But, what the authors don’t mention is that the quality at high ISOs on modern DSLR’s is now very good indeed.
Given that high ISOs, especially if combined with prime lenses, enable you to take photos with a hand-held camera in low light conditions, when the quality of light can be amazing for subjects like portraiture, I think they are worth experimenting with. Embrace high ISO. Use it whenever the light is low. It depends on what camera you have, but you may be surprised how little noise there is at ISO settings like 1600, 3200 and 6400, especially if you follow the tips presented later on in this article.
There are several factors that make the high ISO settings more usable on recent digital cameras:
- Sensor technology and noise reduction. For example, the latest EOS cameras use the DIGIC V processor. The DIGIC V is faster and more powerful than previous versions and one of the benefits of this is that it’s better at reducing noise when you use the JPEG format (if you use RAW, noise reduction is carried out by your RAW processing software instead).
- Sensor size. If you have a full-frame camera it produces images with less noise at high ISO’s than cameras with APS-C sensors. (All of the photos in this article were taken with a full-frame EOS 5D Mark II).
- Better software. The noise reduction algorithms in the latest versions of Lightroom and Adobe Photoshop work amazingly well. As RAW processing software gets better over the years, so does its noise reduction function. (The photos in this article are processed with Lightroom.)
High ISO Techniques
There are a couple of things that you can do to help avoid excess noise at high ISOs. These apply no matter which ISO setting you are using, but the improvement in quality is more noticeable at high ISOs than low ones.
Expose to the right. This requires that you set an exposure that gives a histogram that leans all the way to the right without crossing the right hand side of the graph. In other words, there are no clipped highlights. This technique works well in low contrast conditions when the brightness range of the scene is less than the brightness range the camera’s sensor is capable of recording.
Aim for your photographs to be exposed more the right side of the histogram, trying to avoid clipping.
In the above example, I was able to increase the exposure by two stops over that recommended by the camera without clipping any highlights. This was made possible by the low contrast of the scene.
Take care in post-processing. If you lighten an area of your photo that is dark, you increase noise levels. The higher the ISO used, the more noticeable this is. If you have dark areas in your image, it’s best to leave them that way. Incidentally, you can make light areas darker without increasing noise, and this is one of the reasons that the expose to the right technique works.
Using Texture To Reduce Noise
Be aware that you will get noise in blue or black skies. Noise shows up most in areas without much texture, such as sky. It is also more pronounced in the blue channel. If you take a photo at high ISO and include blue sky or the night sky in the image, you will see a lot of noise in the sky. I don’t want to put you off taking photos that include sky (such as the one above) as you can create some beautiful images that way, but you should be aware that they will contain more noise than photos without sky.
Alternatively, if you take photos of something that contains a lot of texture, such as the books in the photo above, the texture has the effect of obscuring noise. Using the noise masking capabilities that texture has on an image can effectively boost the quality of your high ISO photography when it is taken into consideration during the composition phase.
Grain and digital noise can be used as a creative tool
A little critical thinking and you may be able to visualize new ways to frame your photograph so the texture is at its most beneficial position inside the image.
Use Noise Creatively
With early digital cameras noise was so pronounced, even at low ISOs, that most photographers wanted to reduce or eliminate it. But, now that high ISO performance has improved so dramatically, maybe it is time to start exploiting the aesthetic qualities of high ISO?
For example, photos taken at ISO 3200 and 6400 on my EOS 5D Mark II and processed in Lightroom 4, such as some of the images used in this article, have qualities similar to that of grain on fast films. Photographers like Sarah Moon and Robert Farber used high speed film and grain to create beautiful, evocative images in the seventies. Their subjects predominantly included portraits and the female nude. Maybe the day will come when a photographer makes their mark by using high ISO creatively the same way?
Get creative and start experimenting with whatever DSLR you have, you may discover new ways that you can use digital noise to add drama to and even enhance your photographs.
Understanding EOS: Andrew Gibson’s New Book
About the Author:
Andrew S Gibson is also the author of Understanding EOS: A Beginner’s Guide to Canon EOS Cameras, which takes a simple approach to using your DSLR by exploring only the controls that you need to learn (such as Aperture priority) to create beautiful photos.