I made a video recently with a good friend of mine, Peter Forsgård, and we talked about some common photography misconceptions. At least to us it looks like those things are often misunderstood or poorly explained.
One particular matter stood out, divided people and even provoked a few heated comments. That was the ISO value which we claimed is one exposure value in addition to the shutter speed and the aperture. We understand that the ISO does not regulate the amount of light entering the camera but it does affect the brightness of the final picture. On top of that if we change the ISO, we also have to change at least one of the two other values, the shutter speed or the aperture.
When we are evaluating the exposure of a photo, we look at the brightness and it’s actually impossible to separate the ISO from the equation by looking at the photo. We might even say that the exposure is spot on even though we don’t know if the ISO was used to arrive to the final brightness of the photo. For example, the photographer was on manual exposure and wanted to use certain shutter speed and aperture but had to crank up the ISO to get the brightness to their liking.
So, even if the ISO does not do anything to the light entering the camera I’d still like to think it’s part of the exposure because of the things I mentioned above. It’s also easier for a beginner to understand the relation of all the three values if the ISO is handled as an exposure value.
One thing that probably surprised me the most, though, was how emotionally touching this topic was and how upset it made some people. I hope by now everyone has recovered and back to happily snapping some great photos.
Please take a look at the video below if you haven’t seen it yet