ISO Explained

There was a bit of confusing and I received a few questions yesterday regarding ISO and what exactly it is and how it works. In this video, I delve a little deeper.

ISO is easiest to visualize when we consider film photography. ISO literally refers to the size of the silver halide crystals that are on the plastic film. The smaller the crystals the smaller the ISO number and the larger the crystals the larger the ISO.

So what effect does the size of the crystals have on the images? The larger crystals are more light-sensitive so they can absorb more light and need less light to produce a quality image, the smaller crystals need more light to produce the same image. The trade-off comes in the form of graininess in the image. The original “pixilation” if you will. Now grainy photos can be quite cool, especially if you’re aiming for spooky fall photos but not so cool when you’re trying to get technical details so the ISO choices will largely depend on what you’re trying to achieve in your photography.

Generally speaking though the lower the ISO the better with regards to detail.

In digital photography, we don’t swap out our light sensor for one that is more or less sensitive to light so what happens is the computer in the camera will computationally boost the values of the light hitting the sensor in low light situations or if the ISO is manually increased. The effect as anyone who’s taken a low light photo with a smartphone will notice is a grainy photo. Since the effect is almost exactly the same as in the film the name and paradigm work well in both instances.