Digital Noise

[kenpossum]

One of the constant problems that bird photographers have to deal with is digital noise. What it looks like in your photograph is a mass of tiny coloured dots in areas that should be solid colour. In the days of film, we referred to these specs of colour or B&W dots as grain.

Below is a image taken of a red-tailed hawk at Sumas Prairie. You may notice the noise in the background. It was taken at ISO 1600 in order for me to have a shutter speed of 1/1000 sec.





Digital noise is a serious problem with non DSLR cameras (a digital camera with non-removeable lenses) when the image is enlarged. It reduces somewhat when a DSLR is used. Digital noise increases under the following conditions. 1. When The ISO is increased, 2. long exposure times. 3. smaller CMOS sensors. 4. digital zooming.

Everything in photography is a trade-off. Staying with a low ISO (ie 100-250) results in less digital noise, but a slower shutter speed. Your bird in flight may not be as sharp as you want. When we increase our ISO to 1000 - 1600 to increase our shutter speeds in order to freeze motion, increased noise results.

Optically zooming (using your lens to zoom in) results in higher quality image compared to using your computer software to enlarge your image. Thus, the longer your lens focal length, the less noise you will have.

Shooting is brighter light will result in a less need to increase the ISO, so here in the Fraser Valley we wait, and wait, and wait for those brighter sunny days.

The more megapixels your camera will use to capture your images actually will increase noise in your image. This is a result of increased information being crammed into the same CMOS area. Advanced DSLR cameras are attempting to address this problem.

Shooting is RAW/ NEF increases the amount of digital information in your image. That results in your image 'holding together' better when you enlarge it. RAW does require post processing with the appropriate software, but the results are certainly worth it. If you are not used to shooting in RAW/ NEF format now, I recommend setting your camera to RAW plus high res Jpeg. I also recommend obtaining a 2 Terrabyte external drive to store your RAW images on as RAW eats up memory like no other. This way, you will have your best images stored away in RAW format come the day when you are ready to learn RAW post processing. You will be thankful you did.

There are noise reduction software available but I do not have experience with their use.

I would appreciate any other suggestions on how to deal with the digital noise problem ... and no earplug suggestions please!

[Gord]

Noise in photography is one problem that did not really leave from film to digital photography. However, Ken is right that there are some programs that can help smooth it out without losing crispness of what you're taking pictures of. I dont have much to share on that though. I do agree that shooting good shots in RAW is not a bad idea. A lot more can be done to these photos should the need or desire arise in the future. The problem is that one RAW photograph is about 25mb in size depending on camera etc. That can fill up computer memory quickly so solutions (the external drive recommendation is a good one) need to be considered.

Ken, I think that you mean for point 4. that noise increases with 'digital' zooming.

Some thoughts on ISO and noise.

Nature photography, for the most part, depends on available light. Sometimes, flash can be used but not always. If flash or nice sunny days were always possible (and the subject IS actually in the sun, or in range of flash and/or not going to be disturbed by flash) then ISO and resulting noise issues would not be an issue.

I say capture an image as number one priority. If it's a crummy darker day, resign to having to use a bit of a higher ISO if slower shutter speeds are not possible to compensate for ISO.

That being said, I often shoot 400-560 ISO with pretty good results during grey days. I can get decent shutter speeds but do notice a bit more noise over my preferred 200 ISO. I think that noise is better than blurred photos. If I shot off a tripod, I might get a bit more leeway but this is not always possible.

Often in bird photography, I shoot pretty much wide open (shallow depth of field). This gives me lots of room for higher shutter speeds and lower ISO. The shallow depth of field is nice to make the subject pop out a bit. It is worthwhile to note the subject though as too shallow a depth of field can make parts of the subject out of focus.

When I do landscapes or still life, I go opposite and often off a tripod. The ISO remains the same, but often the aperture is smaller to permit more depth of field to get more landscape in focus. The shutter speed is much slower.

Unless shooting in really dark conditions, I find I can work with ISO between 200 and 400 quite well.

That's it in a nutshell. I certainly encourage any questions on the above for clarification as there is a bit of lingo in there.

[kenpossum]

Thanks Gord Yes, I meant digital zooming. Sometimes my brain keeps making these "brain-typos". Thanks for your comments on the ISO settings you prefer under various light conditions. My settings tend to be the same, and it would be great to hear from others on here. The proof is in the pudding, so they say, and your results verify your ISO setting choices - fabulous!

[kenpossum]

While at Reifel, Dave P. and I came across three Saw-whet owls. As usual, they were hidden deep into the tree foliage, and the lighting was already poor. I could have continued with the ISO 1000 - 1600 setting I was using for birds in action, but I knew the trade-off would be increased digital noise. As is often the case, the Saw-whet is a master at playing statue, so I chose to use an ISO of 320 which would reduce the noise, and result in a sharper, crisper shot. Such a low ISO in that light resulted in a shutter speed of 1/13 sec. No problem, for unlike many of the photographers there, Dave and I were using our tripods.

[Janne]

What a lovely little Northern Saw-whet owl. My camera won't give a 320 ISO but probably the ISO 400 would work.
Janne Perrin
Harrison Hot Springs

[kenpossum]

My aim in this photo was to reduce digital noise by using a lower ISO. This resulted in a very slow shutter speed (1/13sec). You could have done this with your camera Janne.