What is ISO and how does changing it affect your food photography? It’s critical to understand this important element of photography. Read this post about mastering ISO for food photography to learn all about it and see examples of ISO in action!
Anybody who is serious about improving their food photography (that’s you!) knows that it takes more than just the push of a button to get a great shot. There are so many elements that go into getting great pictures (like the best lenses for your photo shoot) and a lot of technical things to master (like shutter speed). Today I’m going to teach you about one of the absolutely essential components of photography, and that is ISO.
What the heck does “ISO” stand for? (Am I the only one who has ever wondered this?) It’s actually an acronym for the International Standards Organization, which is a standardized industry scale for measuring the sensitivity to light. So in your digital SLR camera, you’ll have a function for either raising or lowering your ISO. In other words, you’ll get to choose how sensitive your camera sensor is to light.
Depending on your camera, ISO can range from 50 up to 6400, with many cameras having a standard range between 100 and 1600. The lower the number, the less sensitive your sensor is to light.
Here’s a diagram from my camera manual showing what the ISO may look like for you. You may need to consult your camera manual if you are not sure where to see your ISO settings or how to change them.
So why would you ever need to change your ISO? It’s because light is always changing, and you’ll need to adjust your ISO to capture the right amount of light to get proper exposure.
I’m going to address exposure (how light or dark your image is) in a future post, but briefly, let me explain that there are three things that affect your exposure. Your aperture (how wide the diaphragm in your camera lens opens), your shutter speed, and your ISO.
Now we all want sharp, clear images, and one of the most important ways to get that is to have a high enough shutter speed so that you don’t shake the camera while you’re taking the picture. (I explain all about this in my post, Food Photography Essentials–Mastering Shutter Speed). In situations with lots of light, you don’t need your sensor to be very sensitive and gather a lot of light, because there is plenty of light to allow for a high shutter speed. But as the sun goes down (or as you enter a building), there is less light, and therefore, your sensor needs to be more sensitive to pick up that light and keep your shutter speed high enough so that you don’t get camera shake.
Typically when you take pictures of food, you’ll be taking them next to a window with natural light. Depending on where you are in relation to the window, the intensity of the light, and the time of day, you will need to raise your ISO (unless you are using a tripod, which I also address in my post on shutter speed). Early in the day when there is plenty of light for me, I can use an ISO of 100 or 200. Later, when I’m trying to beat the setting sun and take pictures of my dinner before it’s too late, I need to raise my ISO to 400 or 800.
Now you may be wondering, “Why don’t you just keep your ISO high all the time? That way, it will always be super sensitive to light and you won’t have to think about changing it.” Well my friends, everything in photography has a trade-off. There are consequences for having a high ISO. Namely, noise in your image. If you don’t know what I mean by “noise,” I am talking about the spotty quality that shows up (the spots can either be white or in many colors). You can particularly notice them in the dark areas of your pictures. Perhaps it’s best if I just show you what I mean.
(The following pictures are best viewed on a computer rather than a mobile device. If you are viewing this on a phone, you may have to zoom in to be able to see the noise in all the images that follow in this post).
Here is a series of pictures taken at different ISO settings. At full-size, you can’t tell any difference between them.
If you look at the camera settings for each of these pictures, you can see that the aperture is the same for all of them. You also may notice that there is a parallel relationship between the ISO and the shutter speed. As you double your ISO, you can also double your shutter speed and get the same exposure. For example, when I doubled my ISO from 400 to 800, I also doubled my shutter speed from 1/200/second to 1/400/second. So the quickest, easiest way to get a higher shutter speed is to increase your ISO. (I should mention that I shot this all in Manual mode and so I had total control over my settings).
But remember that trade-off I told you about? Even though the pictures above look the same from far away, watch what happens when we zoom in.
Look particularly in the gray area toward the top third of the picture. (It may be hard to see on your screen). You should be able to see the difference between the smooth area in the ISO 100 picture and the spotty area in the ISO 1600 picture. If not, here they are super-sized for you:
Yikes! That is a lot of grain! We’d really like to avoid that as much as possible. There are two ways to do it:
- Get proper exposure
- Keep your shutter speed low and/or use a tripod along with a low ISO
Now I think I could have made my pictures a little brighter and that might have helped with the noise. (All of these pictures are straight out of camera, with no editing whatsoever). You might just say, “Well hey, I can use a low ISO and shutter speed and just increase the brightness in Photoshop/Lightroom/Picmonkey/ afterward. Don’t be tempted to just “fix it in post.” Increasing the exposure in an under-exposed picture will ALWAYS add grain to your pictures.
Again, here are those comparisons full-sized for you.
ISO 100 (under-exposed image with brightness increased in Lightroom)
ISO 1600 (under-exposed image with brightness increased in Lightroom)
The bottom line is, ISO can be your best friend or your worst enemy. Generally, you will want to use the lowest ISO you can while still keeping your shutter speed high enough to get a clear, crisp image. If you have to choose between using a slow shutter speed and using a high ISO, choose the high ISO. There are ways to minimize grain in post production, but there is no way to save a blurry shot. And even a grainy shot is better than a blurry shot.
Hopefully that was helpful (and not too confusing!) If you’d like to improve your food photography, be sure to read my other articles in my Food Photography Essentials series. If you have any questions, please leave them in the comments! And be sure to pin this so you can come back and reference it again!