Auto ISO

As a manual photographer, I never liked the idea of the camera taking over the ISO because I assumed it led to increased noise in my photography which I found more noticeable when viewing images on a cellphone or laptop.

Noise can be defined by random variations of brightness or colour information in images. Several reasons include poor lighting, high ISO settings, long exposure times, and heat can increase image noise. Noise can also be introduced into an image during the editing process.

In 2020, Nat Geo Wildlife Photographer and Nikon Ambassador Richard Peter’s introduced me to Auto ISO via the Guild of Photographers and explained why I noticed more image noise when viewing photos on a cellular device or PC monitor. Since then, I’ve experimented with Auto ISO, and I’m finally beginning to like it.

Most of us view an image on cellphones, tablets and laptops at approximately 10-15 inches away, while those viewing images on a PC screen average about 25 inches away.

The images we view on mobile devices, laptops and PC screens are also smaller, so we often view an image closer than we would a 60×40″ inch large format printed image. In addition, we can view pictures even closer on an electronic device by zooming in, something the naked eye cannot replicate.

In contrast, most of us view framed prints between 40-50 inches away because we can see the picture more clearly than an image viewed from a mobile device, laptop or PC.

Therefore, noise will always be more visible on an electronic device than in printed images. Furthermore, the smaller the ‘pixels’ on the image camera sensor, the more noise will be recorded.

It is also worth noting that most photographers habitually view images up close during editing to check for excess noise. Therefore photographers will become more aware of it, whereas members of the public don’t view images as closely as we do, nor are they assessing an image for noise.

What is Auto ISO?

Auto ISO is what it is, a setting that automatically adjusts the sensitivity of the camera’s sensor to light. The higher the ISO, the more significantly the camera can capture images taken in low light. A lower ISO value means less sensitivity to light.

Auto ISO is a camera setting (feature) that automatically tells the camera to alter the exposure based on the lighting conditions. In reality, its not that different from manually changing the camera ISO.

As mentioned, I wouldn’t say I liked the idea of adopting the Auto ISO feature because I felt it would simply do its own thing, thus making my life more difficult. However, that’s where I was going wrong.

Auto ISO feature can be set to a minimum and maximum setting, which, as explained is not that much different from manually adjusting the ISO, the only difference is that the camera is intelligently adjusting the sensor’s sensitivity to light so that you don’t have to.

For example, when shooting landscapes during the golden hour (sun setting or rising), I dial the minimum ISO setting to 100 and the maximum to 500. Auto ISO will automatically adjust the sensor’s sensitivity to light while I concentrate on focus, aperture and shutter speeds. Should I need to increase my baseline ISO and maximum ISO, I can do so in the settings and carry on as usual.

Why use Auto ISO?

Using Auto ISO is an automated way of being able to control the brightness of an image while you can concentrate more on achieving the following:

• Sharp focus
• Freezing movement
• Blurring movement
• Getting the correct depth of field

Auto ISO is also essential for wildlife and golden hour photography.

When to use Auto ISO

I’m a landscape and low-light photographer. Therefore I prefer to use the Auto ISO feature when I need to concentrate on focus, shutter speed and aperture when shooting in manual mode. However, it all depends on how you like to work.

The Auto ISO feature is great for:

• Golden hour photography
• Street photography
• Handheld photography
• Wildlife photography
• Sports
• Concerts
• Weddings
• Lifestyle and family photography

Disadvantages of Auto ISO

As with most technology, Auto ISO does have several disadvantages, such as:

• You could end up with images that are too light or dark
• Your exposure meter will naturally want to over-expose a scene, especially in dim light
• Auto ISO may limit other shooting features, such as Aperture Priority and Shutter Priority, thus ending up with images that are too light or dark
• When shooting in Aperture Priority or Shutter Priority, the exposure indicator is not always visible, and on some Sony models, the Auto ISO meter is hidden
• When shooting in manual mode, Auto ISO does not always choose the correct exposure
• Auto ISO can lull you into a false sense of security
• Some camera makes have a limited exposure compensation range when operating in Auto ISO
• No extended ISO values

Conclusion

Automatic ISO is widely used by both professional and beginner photographers alike.

Auto ISO is a great feature that I’ve used on old and new Sony and Lumix models, and as yet, I’ve not experienced any significant issues.

The image below was shot using Auto ISO on the Sony A7ii. The minimum ISO was set to 100, and the maximum to 500. The highest the ISO went up to was 200, and I photographed this image—one-hour past sunset.

While the Automatic ISO feature has several disadvantages, the key to remember is never to let it lull you into a false sense of security.

Remember what your manual ISO settings would be, for example, a sunset scene, and if the Auto ISO setting does not feel right, disengage it or revert to manual or your preferred shooting mode.

However, as mentioned, I’ve not yet experienced any issues using Auto ISO on old and new Sony, Lumix and Nikon models.

Furthermore, its essential to remember these simple steps to reduce image noise:

• Shoot in RAW
• Get the correct exposure with a few test shots first
• Always maintain a low ISO
• Keep your long exposure shots under 30 seconds
• Use large apertures
• Enable your cameras noise reduction
• Take advantage of your cameras high ISO noise reduction (if you shoot in Jpeg)
• Use a decent noise reduction software
• Religiously check each image after shooting it