NOISE AT HIGH ISO
Digital noise in digital photography is the equivalent of what is called grain in film photography, and is typically caused by shooting at a high ISO sensitivity, usually greater than ISO 800. Without delving too far into a technical explanation of digital noise, suffice it to say that it relates to how the individual pixels in your camera’s sensor convert the light striking the sensor into electrical signals, which the image processor “processes” to create the resulting image.
Typically, you increase the ISO sensitivity to more than 800 when the light is low and you don’t want to use a flash, or you’re shooting where it isn’t allowed. Shooting conditions may also make it necessary to shoot at a faster shutter speed to stop action, such as indoor sports: basketball, etc., which is another reason you might hike the ISO to achieve a proper exposure and sharp image.
Handholding your camera at a slower shutter speed in low light could cause camera shake and blurred images. The solution is often a tripod, but not all shooting situations make it practical to use a tripod, as you must be on the move to capture your photos.
For two primary reasons, digital noise is not necessarily a condition to avoid.
- If you expect to generate sharp, properly exposed photos, especially if you’re a professional on assignment, then you may have to be willing to allow for some visible noise. Again, you may not have an alternative if you don’t happen to have a flash unit with you or you’re not permitted to interrupt a sporting event, concert or a speech with the light from a flash. Many of the better wedding photographers purposely don’t use a flash, so they can work close to their subjects without blasting a light in their faces.
- Once you understand digital noise and how it occurs, you can control it and use it as a creative element. Noise could help to emphasize textures or give a photograph grittiness, if, for example, you shoot many street and urban scenes and subject matter.
Fortunately, the technology of digital photography also provides methods to eliminate or reduce noise that weren’t available to film photographers.
- Virtually all of the newest DSLR cameras, from budget-priced entry-level models to the most expensive pro bodies, have been engineered with advanced technology to control digital noise. This technology is also found in the newer interchangeable lens camera systems, or mirrorless cameras, and many of the high-end compact cameras.
- The other advantage digital photography has over film photography for controlling noise is what can be done with noise reduction software compared to the limited methods of the darkroom. For example, Dfine® 2.0 from Nik Software is compatible with Adobe® Photoshop® CS3 through CS6, Adobe Photoshop Elements 8 through 11, Adobe Photoshop Lightroom 2.3 through 4 and Apple® Aperture® 2.1x and later. You’ll find it quite easy to take control of digital noise with Dfine during post-production with any of these popular editing software products.
Like any digital photography concept, once you make noise part of your knowledge set, there is no reason to be afraid of its effect and, in fact, your use of it creatively is a sign that your skills are advancing and you have more control of the shooting process.