If you own a DSLR or fancy point and shoot camera, chances are good that you’ve looked longingly at that little 3 letter excuse for a word and thought, what is ISO? Then you probably dreamed of a world where you were clever enough to figure out what the hell it means. Hey, me too! It’s one of those things that people see every day and pass off as unnecessary or complicated, like brushing your teeth or trying to sync an iPhone without duplicating every damn song. So, in the spirit of exploration, knowledge, and taking better video and stills, we will now decrypt the question, what is ISO.
What is ISO?
Changing the ISO adjusts how sensitive your camera is to light. With a lower number of 320, it is less sensitive to light (darker) than with a higher number (brighter) like 3200. In fact, 3200 is significantly more sensitive than 100 (if you couldn’t tell by just reading the numbers). As a general rule of thumb I never let my ISO go above 1200. Higher than that and you’ll start seeing noticaeble noise which to me ruins the image.
In general, you want your ISO to be as low as possible while keeping your image bright enough to see a range of colors. The reason people use ISO, is because it’s usually the last setting to max out in low light conditions and it will indeed make the image considerably brighter. Great right? Wrong, there’s a catch. ISO has a direct relationship to digital noise, so the higher the ISO, the more digital noise. When there’s plenty of light, it’s super easy to keep your ISO down, the problem is when you’ve got no light, so the message is, if possible, always bring a flash or light, it will make a world of difference.
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Unfortunately on occasion low light is unavoidable, and when choosing between not being able to see and seeing a crappy noisy image, the decision is… suprisingly painful. However there are plugins, one specifically I recommend for video, that can do a good job in reducing the noise levels in post. I’ll list the info at the bottom, underneath the heading Neat Video.
What is Depth of Field?
ISO does actually have one important function that it’s now time to cover. Aside from controlling the brightness of your images, ISO in tandem with iris, controls your depth of field. While ISO controls your camera sensor’s sensitivity to light, the camera’s iris controls how much light hits the sensor. Wide open = more light = shallow depth of field… don’t ask me why, but it is a fact.
A Shallow depth of field is most common in films although the DSLR epidemic is mostly based on their ability to produce a seriously shallow yet cost effective depth of field. Depth of field refers to the spacial distance that is in focus for a camera. A shallow depth of field is when the foreground is in focus (ie a young couple kissing in the rain) and the background is soft, or out of focus (blurry rainy, night). You see this most commonly during dialogue and close-ups of any kind. A deep depth of field is exactly the opposite. Objects further apart from one another still remain in focus. The best example is landscapes, mountain range or establishing shots. Ok enough background, time to explain.
Since a wide open iris equals bright and shallow depth of field and a smaller, darker iris equals a deep depth of field. That means you can control your depth of field by balancing ISO and Iris. Close your iris some, image gets darker with a deeper dof, but then you turn your ISO up a little. This is a good idea when you’re recording action or movement in general because it’s easier to pull focus when the range of focus is deeper/larger. Opening your iris up makes the image very bright but the dof very shallow. Turn the ISO down to balance the lighting. A shallow depth of field is great for many reasons. Most importantly, it’s more personal and it drives the viewers attention but a big reason we find it so pleasing is because we associate it with film… for example, what looks better to you, film or tv? (I openly admit the film association theory is more my selfish opinion than deep-rooted fact)
Your kids like dinosaurs. Or fish, or turtles… or something. Something that requires you to enter a low-light area to capture a priceless memory. Inside the museum or aquarium, an ISO setting of 100 isn’t going to work. There’s not enough light to take a good photo with a setting that is incredibly sensitive. To add to your problem, you’re surrounded by other happy families that want their kids make their best fishie face in front of the glass. Setting your flash off in this place will not only annoy everyone around you, it’ll just reflect terribly off of the glass and might even scare some fish to their unfortunate public deaths. This is when you ask a critical question: how do you get the perfect shot without the flash?
If you crank your ISO up into the thousands, you might get the shot, but it probably won’t be perfect. The colors will die, the noise will run rampant and the memory will be clouded in regret. If you keep it too low, the lack of light will ruin any hope of getting a good end result. You have to find the balance point; it’s the adequate combination of light and picture quality that will make your life substantially easier. Play around with the ISO and find the perfect setting for the room you’re in. Take a few. Make your kid stand there for days. It’s worth it. Once you understand how your camera works and know its tendencies, you can get that shot much faster.
A Plugin that Works
If you’re using your DSLR for video or your video camera has ISO or whatever the reason for capturing noisy video. Here’s a plugin I highly recommend. Neat Video sells a filter for basically every editing software that does a very good job of removing as much noise as possible. I’ve tried other denoising plugins and seriously none even compare to this. Most either didn’t work or worked by blurring the image beyond acceptable levels. Neat Video is actually easy to use, but with more advanced settings if needed, and it works in my opinion as best as a noise reduction plugin can work. Rendering isn’t bad either.
Go at it!
So, there you have it. That should more than answer your silly question of what is iso, now you can scoff at those who don’t know. The most important thing is to be interested and have a desire to learn and get better. Actually just the fact that you’re reading this is a good sign. Keep shooting and keep learning…. more importantly use your information to become the life of the party at a party when someone asks what is iso. It might be a trivial pursuit party but still cool but seriously what is iso ?