Don't use a low ISO, use the right ISO setting

Monday 11 September 2023, 15:51 by Nando Harmsen | 9,504 views | 10 comments

This article was translated from Dutch with the help of AI. Read the original.

A high ISO setting causes noise. That's why the advice is to choose the lowest ISO setting. This gives you a noise-free image. However, don't be afraid to use high ISO settings, or your photos may fail. So don't choose a low ISO, choose the right ISO.

There are three settings you can use to control the exposure. The aperture, the shutter speed and the ISO setting. The right combination of the three gives you the correct exposure. These settings also have another effect on the photo.

Nando large depth of field slow shutter speed

A large depth of field caused by a small lens opening. This always results in the need for a longer shutter speed.
The aperture, the lens opening, controls the depth of field. The smaller the lens opening becomes, the more depth of field you get. You therefore choose an aperture based on the desired depth of field.

A fast shutter speed is needed to freeze fast movement. This is 1/2000 of a second, and it cannot be lower without getting motion blur.
The shutter speed determines how long light falls on the sensor. A shutter speed that is too slow causes motion blur. You choose a shutter speed to prevent motion blur, or to deliberately make it visible.

Noise at a high ISO. It is not desirable, but sometimes a high ISO is needed to make your photo work. This was taken at ISO 12,800 and the noise has been increased for illustrative purposes.
ISO is analogous to the sensitivity of the sensor. The higher you set the ISO, the less light you need for a good exposure. The downside is the increase in noise at higher ISO settings.

You can see that the aperture and shutter speed determine how your subject appears in the image. ISO does not. Put simply, it only causes noise when you set it too high. The advice today is to keep it low to maintain good image quality.

However, a low ISO setting is rarely the right choice. You should not choose a low ISO, but the right ISO setting. This means setting the ISO high when the situation calls for it. If you don't, your photo will fail.

A fast shutter speed was needed to keep the bird sharp. But there was not enough light to do this at a low ISO. If you set the ISO higher, this is the result.
Are you choosing a fast shutter speed because you want to freeze movement? Then your widest aperture may no longer be enough to let sufficient light reach your sensor. You then have to raise the ISO, sometimes even to ISO 3,200 or more. So do it.

Motion blur caused by a shutter speed that was too slow. This is 1/13 of a second because the aperture was stopped down for a large depth of field and the ISO was set to 100.
Is a large depth of field needed? Then you have to stop down the aperture. This causes a slower shutter speed. If you don't have a tripod with you, or your subject is moving, motion blur will occur. You can only solve this by using a high ISO setting.

ISO is an indispensable setting for a successful photo. It is ideal if you can keep it low, but that is not necessarily the best ISO setting. Choose the ISO that gives you a successful photo. That is the only right ISO setting.

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About the author

Nando Harmsen has been photographing for more than 40 years. He specialises in wedding photography and landscape photography. Nando also gives talks, workshops, masterclasses and photo trips, and regularly reviews new and interesting equipment.

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10 comments

Donald Willemsen wrote on Tuesday 12 September 2023 at 10:38 | reply
Nando, it is once again a clear and easy-to-understand story and I think you are right.

I mainly work with Aperture Priority (Av) because I photograph a lot of static subjects and DoF is important to me. Because I don't always have a tripod with me, I therefore have to use reasonably short shutter speeds to prevent motion blur.

The noise performance of my R7 is good and I can almost always increase my ISO value to ISO 6400 without having annoying noise. Any noise that may be present can be removed well in post-processing.

In my camera's settings, I have set the auto ISO with an upper limit of 6400. With handheld shutter speed, my lower limit is 1/60 sec.

I then have the following question: How does the camera determine the ISO value when 'auto ISO' is set and I apply ETTR as standard with +1/3 stop?
Translated from Dutch.

Nando wrote on Tuesday 12 September 2023 at 11:47 | reply
The camera doesn't look at any exposure compensation. It only looks at the shutter speed.
If that shutter speed is below the threshold you set, the camera raises the ISO one notch.
Translated from Dutch.

Rene wrote on Tuesday 12 September 2023 at 11:24 | reply
Use the ISO recommended by the manufacturer. The lowest ISO does not always produce the least noise. For my camera, that is 200. 100 and 64 are also possible, but the manufacturer warns that the dynamic range will be lower and therefore the base noise higher.
Translated from Dutch.

Nando wrote on Tuesday 12 September 2023 at 11:50 | reply
Until that 'recommended' value does not make the photo you have in mind possible for you. Then you have to deviate from that theoretically 'recommended' value. That will usually be the case in practice.
Translated from Dutch.

jan glas wrote on Tuesday 12 September 2023 at 12:15 | reply
Well I already experience annoying noise at ISO 200 plus.
Still better with a Sony A9-2 06 my Sony A1.
Luckily there is Topaz
Translated from Dutch.

Rene wrote on Tuesday 12 September 2023 at 12:16 | reply
The nice thing about it is that noise processing,suppression in programs will continue to get better in the future, so you can now also use older photos with noise and or high ISO
Translated from Dutch.

Paul wrote on Tuesday 12 September 2023 at 16:05 | reply
Clear article again. If, like me, you started with "rolls", this is easier to understand. If you had a 17° DIN = ASA 33 = ISO 33 film in your camera (actually standard in the 60s), you couldn't do much more in the twilight. That's what Kodak had the Three-X for and Ilford the HP4. They were 27 DIN 400 ISO, so ASA 400.
In color even less choice, but everyone knew exactly what was or wasn't possible.
Now you can set everything with a button on your camera, and then there are those crazy gurus who tell the layman that only the lowest ISO value is good, so many people are particularly frustrated with their new camera.
So this piece should be included on all photo pages.
Translated from Dutch.

Donald Willemsen wrote on Tuesday 12 September 2023 at 16:32 | reply
Nando, in my case the camera will not go below the limit I set (1/60 sec). The camera will use the set aperture value and a shutter speed of 1/60 and then increase the ISO value to get a correct exposure. Otherwise the photo will be underexposed.
Translated from Dutch.

Donald Willemsen wrote on Tuesday 12 September 2023 at 16:34 | reply
Paul, totally agree with your last paragraph.
Translated from Dutch.

Mac wrote on Wednesday 13 September 2023 at 08:27 | reply
I always use the lowest possible ISO. And that does indeed depend on the circumstances.
Last weekend I photographed a dance battle indoors again. And the ISO was set to 5000. Any lower, and they were either underexposed, or you got motion blur.
Translated from Dutch.

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