Modern cameras can be set to very high ISO values. But the higher your ISO is, the more noise will be visible. There is a point when the noise levels become higher than acceptable. Do you know what high ISO value is still acceptable for you?
In the old days, light sensitivity of analog film was called ASA. The higher the ASA value, the more sensitive the film was. For a long time 400 ASA was pretty much the highest available. Higher sensitivity film was very rare. If you found it, these films had lots of grain making it almost useless for common photography.
The term ASA has become obsolete and in this day and age we use ISO when we talk about sensor sensitivity. The biggest change since the old days, however, is the possibility to choose a different ISO value for every image individually. But there is one thing that did not change at all, and that's the increase of noise when turning up the ISO which is very similar to the increase of grain in film.
So much about history. Today we have access to ISO values that are astronomically high, especially compared to the old days. Once it was difficult to find ISO 1,600 film (1,600 ASA), but today we frown when we hear about a camera that has just a touch of noise in that sensitivity range. Camera manufacturers are often bragging about what the ISO sensitivity their cameras are capable of. It can get as high as ISO 102,400, ISO 409,600, and more. But they don’t talk about the amount of noise that occur at those astronomical ISO values. Would you dare to use a camera with ISO 25,600 or higher? Or are you afraid of the noise?
Noise is a funny thing. The way we see the noise depends on many things. When a noisy photo is reduced in dimensions and size (for use on the Internet, for instance), noise will become less discernible. When you look at an image on your screen at 100 percent magnification, the noise might be very annoying, but the resolution of your screen can influence the appearance of noise also. And the noise levels may show completely different when you print your photo. Even the viewing distance plays a part. So there are a lot of variables that determine if the noise in a photo is acceptable or not. And I forgot to mention the most important one: every person has his or her personal preferences.
In my workshops and masterclasses I often get the same worries when it comes to night photography and photographing the Milky Way, and every time the same question pops up: is my camera able to use such high ISO values? A lot of photographers seem to be afraid of using ISO 3,200 or ISO 6,400. Often they think ISO 1,600 is the absolute limit and they rather keep their settings way below that limit. When I ask them what they think about the noise levels of their camera, they cannot answer that. Then I push them to go beyond their comfort zone, and most of the times they are very surprised of what quality their camera can produce with extreme ISO values.
So no matter what the manufacturer says about the ISO performance of their camera, or what others will tell you about it, the maximum acceptable noise level it is not set in stone and only dependent of what you find acceptable yourself. Therefore it is very important to determine what you find to be the maximum usable ISO value with your own camera.
There is a simple test that can determine your own personal maximum acceptable noise level of your own camera. Just place it on a tripod in a dimly lit room, and photograph something stationary with every available ISO value. Just start at ISO 100 and turn the dial one stop higher with every shot. Make sure you leave your aperture the same and just compensate with your shutter value. Go all the way up to the highest ISO value your camera is capable of. Make sure the exposure of every photo is the same, and make sure the light level in the room stays the same also.
After that, load all the photos into your favorite photo editing software and check out the images without any post-processing. Compare all images full screen, and also on 150 percent and 200 percent magnification. This way you easily can determine where your personal ISO limit is.
With this little test, you will know up to what ISO value you can go without the risk of ending up with a photo that you find to have too much noise in it. You can even set limits on your camera to be sure you never go over your own limit.
You can vary this test. You can also do some post-processing to see how far you can go. Or you can send the (un)processed files to your printer or online printing service to see how the noise levels will turn out on a 4x6-inch print or a 8x12-inch print. You could be surprised how different noise levels show on a printed photo.
Remember, how you experience noise levels is very personal. Don’t rely too much on the verdict of someone else. Just take a couple of hours and find out what your camera is capable of, and determine until what ISO you dare to go.
It is possible on many cameras to set a limit on the ISO levels. This way you cannot go beyond that maximum acceptable ISO value. But be careful with those limits. Sometimes it is better to have a photo with too much noise than no photo at all. Especially when you have the chance to photograph something that is very rare, or has a lot of personal value to it. The memory caught in a photo can be much more important than any level of noise.
Have you determined how far your camera can go? Tell me in the comment below what camera you use and what your acceptable maximum ISO value is.