ISO and noise in images is a very common topic around the photography forums and Facebook groups I frequent. ISO has become this sort of scary monster. We are afraid to touch that ISO dial. Allow me to set the scene… The golden sun is glistening beautifully through the trees, this is the most perfect session EVER! Then suddenly dark clouds roll in, your beautiful perfect light is gone. Oh no, OH NO!…..you need to bump your ISO! You cringe, and perhaps die a little inside with every click of the dial. Watching that number rise, you get hot, suddenly your palms are sweaty, but you smile at the client like everything is fine, it’s all under control. And then at the last moment, too afraid of that big number laughing at you, you dial the ISO back down to less scary number, and think, I’ll just fix the exposure later in Lightroom. Phew, dodged a bullet there right? Not necessarily!
Digital noise is not solely produced by the ISO number on your display. It has much to do with exposure! It is MUCH more important to have a properly exposed (or near properly exposed) image straight out of camera at the expense of a higher ISO number, than a poorly exposed image that you will “fix” later just to have the “security” of a lower ISO number. This is especially true if you are still shooting in .jpg in which case correcting a very underexposed image in post processing is going to look waaaaay worse than if you had just bumped that ISO. Case in point. Here is an underexposed image shot in .jpg, with a low ISO that I recovered in Lightroom, and a properly exposed image with a higher ISO that didn’t require any recovery. As you can see, the underexposed image with the low ISO that we had to save looks pretty terrible. The only edit done was to bring up the exposure, but you can see it clearly has much more noise, and other problems because we really damaged the files data by having to heavily fix the exposure.
The less editing you do to a digital negative, the more data you preserve. The more editing you do, the more you damage the data. If you have to bring your exposure way up in your editing program, you do more damage to the data, and create more problems than if you had gotten in right, or near right in camera. Editing software is mainly meant to enhance, not fix. Luckily, if we make a mistake (everyone has) it there to fix it, but it’s best to learn to shoot without the “I’ll fix it later” mentality.
Now sometimes, just slightly underexposing an image is a desired effect to help preserve more detail in areas, (especially when back lighting for example) so I’m not saying don’t ever underexpose. There are times when underexposure at the expense of some digital noise is necessary. Shooting in RAW will give you a great advantage in salvaging an image, or underexposing on purpose. I’m not going to go in detail about RAW, but I want to show you that even shooting in RAW, you can still save yourself the editing step of underexposing and fixing later. Don’t be afraid to use a higher ISO to get it right. Even though the salvaged RAW images look much cleaner than .jpg images, the same rule applies. There is less damage to the files data, the less correcting you need to do in post
I am shooting today with a Nikon D610 Full frame body, and a 50mm 1.8G. This body handles noise quite well. It is important to know the limits of your particular camera. smaller sensor or entry level cameras have a much lower tolerance for ISO than more advanced bodies. I’m using more extreme examples. ISO 1600 on some bodies won’t look clean no matter what you do, so you may need to find other ways of letting in more light. Other than my ISO, my other settings remained the same. They are SS 250, F 2.8 I chose a shutter speed of 250 because I feel like that is a pretty safe shutter speed for many situations. I also chose an area of my home that was not lit very well so I could crank the ISO.
Well, you can see right off the bat, that the 1600 ISO image looks better than the 200 ISO image. Less noise too. Now lets take a look at the Edited versions of these to correct exposure. I didn’t have to do anything to the 1600 ISO image. it’s already correct, but I added a touch of contrast just to do something to it.
At first glance, none of them really look that different, and, again that’s one great thing about shooting RAW. It really does help save a bad image, and either of these are usable images in my opinion. But let’s get up close and personal with our 200 ISO VS. our 1600 ISO at a 100%crop to see the difference.
So many of you might be going HUH? looks pretty close. Well, it is, and truly we are just pixel peeping here, but my point is, look how well ISO 1600 did! It did not destroy the image, it’s not full of noise. I was able to crank that ISO and save myself a lot of time in post processing because nothing had to be done. I also think when really studying these 2 images, that the 1600 ISO example is crisper, and has less noise and more detail than it’s corrected low ISO counterpart. So, what I hope to prove with this article is that you really don’t have to be afraid of cranking that ISO dial if it means properly exposing your image to get it right in camera. Again, know the limitations of your camera of course, but don’t be afraid to push your camera to what it can do!