Remember the roll of film?
The final component of exposure is ISO (International Organisation of Standardisation). (the first one was aperture and the second one shutter speed) If you are a bit older, you probably remember rolls of film. If you went to a sunny country, you bought a 100 ISO roll. If you went to a country with less sun, you bought a 200 or even a 400 ISO roll. Thankfully, those days are over and you can now make different choices for each photo.
Try to get used to not using the automatic ISO setting on your camera. Your camera will always turn up the ISO quite quickly in low light, which can cause all sorts of unwanted effects. That said; the newer the camera, the better the noise control so you can play around with that depending on your camera. My current Canon EOS R5 is fantastic at higher ISO. My phone on the other hand not so much. But even there it can sometimes totally be acceptable to have a photo with high noise.
Which ISO to use
Deciding which ISO to use depends on a number of things:
- What aperture do you want to use?
- What is the light level where you are working?
- What are you going to use the photos for?
Effects of high ISO
But first, back to the effect of a high ISO. Firstly, a high ISO allows more light to reach your sensor, resulting in a faster shutter speed (if you are shooting with aperture priority). Ideal, you might say. Unfortunately, this high ISO has some less pleasant side effects. How bad they are depends on the quality of your camera. These side effects are:
- A lot of noise. Noise is best compared to grain. Increasing the sensitivity of the sensor creates ‘digital noise’. This sometimes results in visible pixels, less sharp lines in your photo and faded colours.
- The smaller the sensor in your camera, the worse the effect of noise. Noise is more noticeable on a compact camera than on an SLR (see the photos below).
In the first example you see two photos side by side, the left one taken at ISO 200 and the right one at ISO 3200. Both were taken with my SLR. You may not be able to see it very well on screen, but there is a clear difference in the amount of noise in the photo. However, both photos are still acceptable.
Now compare two photos taken by two different cameras in the same situation. As you can see, the SLR (right) gives much better results than the compact (left). In both cases, the ISO is set to 3200. Now camera’s and even phones change every year. They get better, more slick, more options and so on. So what is true today might not be true tomorrow. So if you have a new camera always test how the camera reacts to high iso.
Personally, I always set the ISO to the lowest setting possible. Are you in a situation where you need to react quickly, you don’t have a tripod and the light is poor? Then the only solution is to use a higher ISO. The only thing worse than a high ISO is a blurry photo!
What will you use the photo for?
Always think about what you are going to use the photo for. If you want to post a photo on your blog that is no wider than 750 px, no one will notice that there might be some noise in the photo. But are you going to send the same photo to a magazine or do something else with it in the future? Then play it safe and use a low ISO (and a tripod!).
