Let’s talk about noise

One of the perennial talking points is ‘noise’ in photos. Or rather how good some cameras are in dealing with noise compared to others and what are acceptable levels of noise. So first off, what is ‘noise’?

Digital noise is the grainy effect we see in our images when we’ve ratcheted-up the ISO, right? Well, not really…the grainy effect we see is the result of the camera amplifying the light hitting the sensor when we dial up the ISO. For example, I’ve already decided on the variable settings I want for the image I want and I don’t want to change them. Let’s suppose I want a shutter speed of 1/1250th of a second to freeze movement and and aperture of f7.1 to give me the correct depth of field. I take a test shot and note that the image is way too dark and that the ISO is around, say, 400. So I increase the ISO in steps until I get the image brightness I want (the meter scale gives me the info I need as well as the histogram). So far so good. I take a final test shot and review the image on the camera’s LCD screen and I’m pleased with the result. I also note that the ISO is now at 3200 and I’m surprised that the LCD image is showing no noticeable noise! What’s even better is that I know I’m shooting in RAW and therefore believe that there’ll likewise be no noise when I process the image. Stop! This is just not true…the LCD image is a Jpeg… regardless of you telling your camera to shoot in RAW. What you’re seeing is not what your camera records. Raw files don’t have any colour, contrast or sharpening applied, but your camera does apply these to the LCD preview ‘in body’ so you can see the image. This is also embedded in the RAW file so that you can see the preview on your editing software. In other words the camera ‘interprets’ and converts the RAW data into a viewable image for display purposes only. Pause here…I think that’s enough for now because I’ll get dragged off on a tangent and spend the rest of this post talking geeky stuff that will probably drive away most readers. So back to ‘noise’…

Now you might think the simple answer to the noise problem is to take photos in good bright light on a really sunny day with no cloud cover. Ideal you might say, but the British weather is extremely fickle and the weather gods don’t always give us what we want. It’s OK if you take non-moving images like landscapes etc where you can afford to wait for that break in the weather, but if, like me, you’re trying to capture that fleeting moment you can’t always wait for the clouds to clear. So you may well have to ramp up the ISO to get what you want. Let’s now assume you’ve taken the shot, opened it up in your editing software at home and are disappointed at the level of noise. This is where most of us ask the question, ‘Do I bin it or try to quieten down the noise?’

If the image is not that important to you then you might well bin it and have done with it…there’s always another day. But what if it is important and you’re loathed to dump it? That’s where the software comes in, right? You push the noise-reduction slider to it’s limit in the hope it does the trick but, sadly, you watch in horror as the image detail disappears before your eyes.

I’m going to go through a few things that you might try… or at least consider:

  1. Convert the image to black and white. This won’t get rid of the noise but when you apply a little noise reduction your photograph still appears detailed enough to make it a ‘keeper’. Of course, this is illusory but as they say, ‘Owt’s better than nowt’.
  2. Use Camera Raw in Photoshop or Light Room and try to get the balance right. Or use the editing software that came bundled with your camera. Canon’s DPP is excellent at getting rid of noise and retaining detail and is very sensitive.
  3. Use specific noise reduction software like Topaz DeNoise AI. A lot of photographers swear by it but, having tried it, I much prefer Topaz Adjust AI. It’s much more flexible and, I think, more sensitive than DeNoise AI, with greater flexibility to retain detail. I’d also add that Adobe Photoshop Express is also good at noise reduction whilst giving you control over detail.
  4. Buy a camera that’s better at dealing with noise at high ISO…hang on a cotton pickin’ minute, before you throw away hard earned cash just take a deep breath and despair not. Remember the exposure triangle in Sharper Images ? Take another look. Everything’s about balance. Of course, there are cameras that handle noise remarkably well (my go-to is the Canon EOS 1DXIII which is quite remarkable when it comes to handling high ISO. Likewise, but not quite as good, is the Canon EOS 5DMKIV), but do you need high-end kit to ensure good noise handling? Certainly not. I also shoot with my old trusty, rusty Canon EOS 60D and provided I get the exposure balance right I don’t have noise problems. Remember, balance of the exposure triangle is the key. Get that right and you reduce noise levels at high ISO. Which means, more keepers and less frustration. Win-win. Sure, you have to compromise sometimes and sacrifice low ISO to get the shot you want but overall I’d say that balancing the exposure is more important than anything. Have a look at your histogram…if it’s too far to the left then, by definition, you are introducing noise, regardless of ISO levels. Consequently, if you try to brighten the image at the editing stage to pump up the shadow detail then you’ll probably be visually-deafened (?!) by the screaming noise. Balance, balance, balance!

Warning!

Beware the Noise Police. They are often accompanied by the the Pixel Peepers. You know the type: they have the unnerving ability to zoom into your photo by use of ‘super vision’ looking for infringements of their Code of Practice which states, ‘All photographic images must be totally noise-free and pixel-perfect’.

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