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Digital Noise The two black bear cubs were busy playing in the tall grass, when all of a sudden something startled them; in a flash both cubs scrabbled up a tree just as Mom had taught them. Unfortunately for this photographer their position was not conducive for a photo. But in a few minutes when their “danger” had passed they immediately made their way down the tree. It was a heavy overcast day so I quickly set my ISO to 800 to try and get enough shutter speed to take an image. Luckily for me both cubs stopped and played on a fallen tree and I was able to capture several images. It wasn’t too many years ago those images would never have been possible, but I think one of the biggest benefits of digital photography is the ability to change ISO at any time. Although I still try to leave my ISO between 100-200 for landscapes and 200-320 for wildlife, there are situations that higher ISO is required for photography especially for wildlife in low light situations. But this also brings up a problem with digital photography when using higher ISO settings, digital noise. So what is digital “noise”? To make it simple, each pixel in a camera’s sensor contains light sensitive photodiodes which converts the light into the appropriate color. When the same pixel is exposed several times by the same light the color of the pixels may not be the same color variation and this is referred to as digital noise. The noise is generally more pronounced on uniform surfaces such as blue sky and darker shadow type areas. The two most common ways that noise is introduced into image is through high ISO settings and long exposures. Even though the noise is different between these two settings it still results in your image with noise. There is a lot of more that effects digital noise, sensor size and possibly the type of sensor. Larger sensors have larger pixels which help in the reduction of noise. Some folks will compare digital noise with film grain. For me I think noise is much worse than film grain. I do everything in my power to reduce digital noise. With the number one factor being that I always try to shoot at the lowest ISO the situation calls for. My Nikon D200 has a noise reduction in camera control for high ISO and long exposures. I generally leave my ISO noise reduction on all the time, it takes affect anytime the ISO is 400 or above and has no effect on lower ISO settings. I will turn on my long exposure ISO which takes affect anytime that my exposure is longer than 8 seconds. The only time this is used is for possible twilight images or longer exposures for some botanical subjects such as mushrooms that are in dark habitats. With my D100 camera which has no noise control anytime I have an ISO above 500, I have to deal with various amounts of noise levels, depending on the subject. However with my D200 with some in camera noise control I am very comfortable shooting at ISO up to 800. Almost all newer digital SLR has at least high ISO noise reduction built in camera. If you are shooting in high ISO situations be sure to turn on the noise reduction. It does make a difference, which is not to say that you may still have to do some post-processing noise reduction. For the last few years all digital camera manufacturers have been competing against each other for mega pixel count, fast shutter speeds etc. Most newer SLR’s have pixels counts anywhere form 8MB to 12MB, with a select few even higher. For the wildlife and sports photographer shutter speeds are now approaching 6-12 FPS. I think the next big competition between manufacturers will be for noise control. A friend of mine and I were shooting together and he was using the new Canon Mark 111, we were in a situation that high ISO was required and his camera was set at ISO 1200. After loading his images onto his lap top, both of us were amazed at the small amount of noise that was present at that high ISO setting. I know the newer Nikons that are coming also will be much better at noise control. So for all SLR camera manufacturers, all I can say is let the “noise wars” begin! Good Shooting Technical Data:
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