Last Updated on July 19, 2022 by Devaun Lennox
ISO is shorthand for International Standard Organization, which is the organization responsible for setting standards across all camera manufacturers. Long story short, they standardized light sensitivity so that all cameras (for the most part) over the last 40 years are made to react to light similarly. And that’s really the main reason why ISO is called ISO, even though it’s a measurement of light sensitivity of a camera sensor. So ISO 100 on my camera will be ISO 100 on your camera, regardless of brand.
Now, there will be some slight variations on the exactness due to wear and tear and the specific environment being shot, but for our purposes, as photographers, it’s essentially the same. And ISO, as far as photography is concerned, simply refers to a cameras light sensitivity. And, as you the photographer, change the ISO setting, your actually adjusting and setting the sensitivity of the sensor of your camera to ambient light.
As camera technology has progressed over the years, the light sensitivity of the sensors has also increased significantly. So much so, that we have the ability to shoot in very dim rooms and still be able to see recognizable subjects with relativity minimal noise. With that, our ability to remain versatile and shoot on the go in ever-changing lighting environments has only gotten better.
Nonetheless, it’s important that you understand ISO and how it affects your photography. And really understanding ISO is a fundamental and key part in even being able to get properly exposed sharp images.
Jump to a Section
What are some common ISO’s?
Common ISO’s are very much camera dependant these days. But, in general, ISO 100, 200, 400, 800 are the most common. Some cameras have the ability to even go as low as ISO 50. The increments ISO go in will be dependant on your camera’s native ISO. Native ISO is the lowest number available in our camera and is also the setting that will give the best image quality possible. Definitely, something to keep in mind.
So, what exactly happens when you change ISO?
Let’s say you go from ISO 100 to ISO 200. What you’re actually telling the camera to do is double its light sensitivity. Both cameras and light in general function exponentially. Meaning, the values go in fractions that either double (when you move up a step) or halve (when you move down a step): 100, 200, 400, 800, 1600, 3200, 6400, etc. So changing from an ISO of 100 to 400 is actually making the camera 4 times as sensitive to the ambient light in the room (since you’ve moved two steps forward).
And moving from ISO 800 to 200 is making your camera ¼ as sensitive. We don’t really need to know any specific or special math here. But, this is important when it comes to getting proper exposure when you’re trying to figure out why an image is too dark or too bright.
Take a look at your camera now, navigate to the ISO settings. Notice that the values only move in doubles?
Wait… Mine have more numbers… Lucky you my friend, that means your camera has an ISO range that moves in ⅓ steps to give you more flexibility. But, even so, this still applies to you as well. When you move from ISO 200 to 400, regardless of the steps between, you will move the overall exposure of the image up by 1 stop.
And that right there, that’s what is happening when you change the ISO setting in the camera. You’re either telling your camera to be more or less sensitive to the available light by the amount you set. By doing these changes, we will directly affect the exposure of our images. We can either increase or decrease exposure by increasing or decrease our cameras ISO. Increasing it will make the exposure brighter while decreasing it will make the exposure darker.
Now, ISO will affect other elements of the photo as well besides overall exposure but know, it will not directly affect either your Shutter Speed or Aperture settings in any way. Shutter Speed can be used in conjunction with ISO to adjust exposure, same applies with Aperture. But both settings have very different affects on a photo than just exposure alone. Even still adjust ISO has no affect on either.
Is a higher or lower ISO better?
Well first thing, what exactly is a “high ISO?” Most photographers would say that’s between ISO 1600 to ISO 3200, depending on what subject matter they shoot. For me personally, I’d say ISO 1600.
As far as which is better, lower ISO is better no questions asked. ISO 100 (or ISO 50 if your camera has that available) is as good as your camera can possibly be and we deliver the sharpest images. However, with most digital cameras now, ISO doesn’t really matter quite as much, especially from ISO 100 to ISO 800. Images across all camera’s and brands will still noise free and sharp.
The issue with higher ISO values is only really apparent when an image is magnified or printed at higher resolutions. On smaller formats (i.e., instagram or smaller online posts) you’ll probably never see the noise in an image or reduced sharpness, even when shooting at ISO 1600. However, if you print an 18 x 24” print or larger, then yes you may see noise, especially in the shadows of the image.
As ISO increases, the sensitivity increases yes. Which does mean you can shoot in low light environments. But so does the amount of noise that your sensor picks up as it eventually begins to struggle to pick up any available light. And that right there is really the drawback. You get noisy photos that aren’t clean and as sharp. Now, increasing the ISO only slightly doesn’t always mean more noise. However, after a certain point, absolutely yes. There will definitely be more noise and a noticeable reduction in sharpness.
In general, 3 stops lower than your cameras maximum ISO setting would be the highest you’d want to set your ISO to if you want to have a usable and recoverable image even with noise that is still decently sharp as well. Now, if you plan on using noise reduction software such as Adobe Lightroom or Adobe Photoshop to reduce noise, then you can shoot upwards of ISO 25,600 and still have usable images.
With that, the lowest ISO you can set your camera to given the situation will always be the best one to use. That’s the best rule of thumb, always set your ISO to the lowest you possibly can. And only go up, if you absolutely need to in order to even take the photo. If your camera goes to ISO 100, then ISO 100 is best. If it goes to ISO 50 or ISO 200 instead, then those are the best settings for optimum image quality.
If you have the ability to shoot in a brighter environment either by increasing the available light, slightly adjust the angle you’re shooting or moving completely, those will always be the best. But, if that’s not possible, set the ISO to the lowest value possible to get the shoot properly exposed.
Before moving on, take the time to do this experiment to figure out what’s the highest ISO your camera can go to without there being too much noise in the image:
During sunset, one evening, go outside and shoot a flower or tree branch. Set the Aperture and Shutter Speed so that you can at least see the image at ISO 100. Then, leave the Aperture and Shutter Speed alone, and shoot one image after another changing ISO only. Shoot these ISO values: 200, 400, 800, 1600, and 3200.
Once finished, transfer each of these images to the computer and look at each image specifically for noise. Whichever image you feel is still easy to view and sharp to your liking (even with a little noise) is the highest you should set your ISO to, period. For me personally, I wouldn’t go above ISO 1200 personally.
When should you increase or use a higher ISO?
The main times you want to increase ISO is the following:
When shooting handheld without a tripod and can’t use a Shutter Speed below 1/80 second.
When shooting action, either indoors or outdoors, and you can’t go below a shutter speed that’s fast enough to freeze the action you’re shooting. For example, a shutter of 1/2000.
Shooting at night or shooting star trails, where you’re shutter is as slow as possible and you’re images are still too dark.
You want to increase Depth of Field, but you can’t change your Shutter Speed.
What are the best ISO values for indoors?
For shooting indoors, stay below ISO 1600 if possible. On most cameras, ISO 1600 will be the maximum that you want to shoot at, only because from there onwards the noise will be incredibly visible. Ideally, for indoor shooting, stay between ISO 400 to 800. If you have a tripod, this would be a very good time to use one.
Shooting on a tripod will allow you to shoot at a lower ISO and, instead, use slower shutter speeds to compensate for the lack of ambient light. In general, that’s the best way to handle shooting indoors in low light so you can avoid having to shoot at higher ISO. Now, whether or not slowing down the shutter is a good idea will depend on what you’re shooting indoors. If you’re shooting fast-moving subjects and need to freeze action, you’re best of leaving the Shutter Speed alone and increasing ISO.
What are the best ISO values for outdoors?
For outdoors during the day, the best will be ISO 100-200. Since there should be plenty of ambient light, there’s no reason to set the ISO higher than 200.
When shooting outdoors at night, the best ISO will be the maximum you feel that the noise isn’t too distracting. See the experiment mentioned above for how to determine that. Best practice is set the ISO to that maximum value, then adjust Aperture and Shutter Speed so that the image is properly exposed.
When shooting at nighttime, since ambient light usually isn’t the greatest, it’s best to shoot on a tripod so that you can shoot at slower speeds to help pick up what ambient light is available and avoid having to increase ISO. But, if you’re shooting handheld, just know you’ll have some noise in your images and very shallow Depth of FIeld when shooting subjects at night.
What to look for in ISO when purchasing a camera?
Well, since ISO is light sensitivity if you find yourself shooting a lot in low light conditions whether they be indoors or nighttime, consider comparing ISO ranges between cameras. Some cameras have larger ranges than others. The drawback of a larger ISO range often means that the sensors are not as sharp as lower range ISO cameras.
But, the advantage is that larger ISO range cameras often have the ability to shoot relatively noise free and sharp images at much higher ISO values than their counterparts. For example, a typical DSLR or mirrorless camera may become noisy at ISO 1600. While the large range sensitive camera may become noisy at ISO 3200 or 6400. In low light conditions, these cameras perform significantly better.