Understanding The Auto ISO in Photography for Beginners
I discussed the ISO in previous post. We know that the ISO is the sensor’s sensitivity to the light. You can set the ISO manually, or by understanding the Auto ISO you can let your camera makes the changes for you. Understanding Auto ISO means how to set the highest and lowest value of the ISO and the minimum shutter speed.
Auto ISO, is it useful?
Almost all new Digital cameras (including new DSLRs and mirrorless cameras) have the Auto ISO setting. Is it really useful? Let’s Take a look.
You can control exposure by using Shutter speed, Aperture, and ISO. Usually you set the ISO to a fixed value and then select what shooting mode you want to use and then set the shutter speed and/or aperture to achieve the right exposure.
When manufacturers introduced the AUTO ISO for the first time, many photographers didn’t like the idea of leaving it to the camera, to set the ISO. And I should say they were right!…to a degree.
Normally, you don’t want to shoot in high ISO, as your photos can get grainy (noisy); having said that, with new sensors you can easily shoot the images at 1600 ISO or even higher, with unnoticeable noise!
Does it mean that I can shoot all of my images in higher ISO?
No. This is not a good idea, and there are several good reasons for it.
The most important reason is at higher ISO you reduce the Dynamic Range of the sensor, which means the camera can not capture as much details in shadow and highlight in higher ISO.
Low ISO, More Dynamic Range
Another disadvantages of higher ISO can be listed as Lack of Sharpness, Chances of getting artifacts in image (Pixelated edges), etc.
HIGH ISO PHOTO
So understanding the Auto ISO and learning the power of it, will help you to shoot sharper and better images faster; with less fiddling around with shutter speed or aperture.
How to set the Auto ISO?
All camera manufacturers use different setups, but in general you can go to the menu and select Auto ISO, then you can set the minimum and maximum ISO values, then set the minimum Shutter Speed, and you are done!
Setting Auto ISO
What is the Minimum Shutter Speed?
In Auto ISO mode, your camera needs to know what is the minimum ISO value that you want to use. In may cases you want to set it to ISO 100. Your camera also needs to know the maximum ISO value that you are willing to use. In most new cameras you can easily allow the camera to increase the ISO 6400. The next thing that your camera needs to know is what is the minimum Shutter speed. When shooting in Aperture Priority and the light reaches below this minimum setting the camera will increase the ISO to maintain the minimum shutter speed. Generally speaking 1/60s is a safe starting point.
Here are some real life scenarios for Auto ISO:
Scene 1: you are shooting a sporting event, and want to keep your shutter speed at 1/1000s and the aperture at f2.8. But some of actions happen in the shade and the others in the light. Turn on the Auto ISO in Camera. Auto ISO is your best assistant in this case. It maintains the shutter speed and aperture combination, regardless of whether your subject is in the shade, or in the light.
Auto ISO in Action
Scene 2: You take photos of children playing in a playground. If you shoot in manual mode and set the shutter speed and aperture, you don’t have to be worried about your exposure; the camera will set it right for you in Auto ISO, regardless if kids are playing in the shadow or the sunshine!
Auto ISO in Action