Hopefully you have read the first couple of posts giving a brief overview into exposure and the three elements that you need to control (aperture, shutter speed and ISO) if you haven’t yet read those you might want to go back and start there or this one might not make much sense 🙂
If you did read those other entries you’re probably thinking this whole exposure issue is a snap. With three variables to play with surely there will always be a way to get enough light? Right? The trouble is each of those variables has limits. So far we’ve learned about the limits of aperture (that your lens only opens up so wide) and shutter speed (slow down too much and your kids will become blurry messes). Now I’d like to introduce you to the one catch about raising your ISO. When you’ve reached the limits of each of the other two variables you will probably be tempted to bump up your ISO (which if you remember makes your camera more sensitive to light). What you might not be expecting is the one ugly side effect of high ISO digital shooting….
Moms… I would like to introduce you to digital noise.
You’ve probably noticed it but not known what it was. You might have even thought it was a problem with your camera. Those pesky speckles of icky looking grainy color. Yes. That is the one snag with high ISO shooting. You can’t get something for nothing and the tradeoff with shooting at high ISO is that you may get noise. How much noise depends on your camera and also how good your exposure was. The good news is that the better exposed your image was to begin with the less noise it will have. Yet another incentive for you to learn proper exposure 🙂 Newer cameras (and more expensive ones unfortunately) tend to have better noise control. It’s something that has been improved steadily over the last few years and hopefully will only continue to get better. There are cameras out there that will allow you to shoot up to ISO 6400 and still have acceptable noise levels. Now THAT is impressive!
So what does this mean to you? Should you keep your ISO low? Well that depends on how much the noise bothers you and what your alternatives are. If there is no way to change your f-stop or shutter speed and you don’t have any other light sources available (we’ll get into flashes in another post) then I say go for it! I’ll take a noisy photo over no photo any day. I would even take a noisy photo over a direct flash photo. There is also no harm in trying the high ISO shot AND the flash shot and comparing when you get home to see which you like better. My other tried and true favorite trick to getting your high ISO shots to look nice is black and white! We haven’t even gotten into the land of “post processing” your images but when we get there black and white will be one of the biggest issues to talk about. Converting your noisy shots to black and white will make them look more like vintagey film grain pictures and less like an accident 🙂
Here are a couple of shots just to illustrate what exactly “noise” is. This shot was taken at ISO 800 so the noise isn’t too terribly noticeable but it is there if you know what to look for. 50mm lens, f 2.8, 1/100th
You can see in this crop of the original image that there is some color noise (the splotches of red and green) in the hair and the image overall is not as “smooth” as it would be normally
Even though the noise in this shot is not terrible I would still probably prefer it in black and white
Lesson of the day? Noise is just one more consideration when deciding what settings to choose to get your perfect image. Does it mean high ISO shooting is out? No. Should you know about it? Yes. As if you didn’t already have enough variables to think about 😉
On a side note I have a lot of ideas for new topics, but I want to make sure that I cover the things that YOU want to know about. If you have a request you can either leave me a comment here or email me at firstname.lastname@example.org I can’t wait to hear from you!