I’ve written often in “To Travel Hopefully” about the importance of learning to go beyond your camera’s full “Auto Mode,” in order to be able to control the exposure of your images. Frequently I like to shoot in full “Manual Mode” so as to be able to choose both my shutter speed and my aperture for full creative control. But in rapidly changing lighting conditions, it is a real challenge to stay in full manual mode, and it’s a big help to allow the camera’s exposure programs to choose the best overall exposure from image to image. There are a few ways to do this. In between the full auto mode and full manual control, there are two common semi-automatic exposure program modes that most photographers are aware of, namely Aperture Priority and Shutter Priority modes. In today’s post I introduce another exposure mode that few photographers are aware of, but that can give the best of both worlds: automatic exposure setting while retaining full manual control over both aperture and shutter speed. This exposure mode is called “Manual Mode with Auto ISO.”
It’s important to be able to control shutter speed because that’s the mechanism by which we can freeze action or allow it to blur for creative effect. It’s equally important to retain control over aperture because this is the means by which we can increase depth-of-field to keep everything in focus or decrease depth-of-field to soften the background. But there’s a third side to the exposure triangle beyond shutter speed and aperture. This third parameter is our ISO setting. Several years ago, most camera sensors weren’t very good at handling noise at very high ISO settings, so we took a risk of ending up with very noisy images if we used our camera’s Auto ISO setting. Not so today. Many modern sensors are quite adept at capturing nearly noiseless images at ISO settings up to at least 3200 and often to 6400 or even a lot higher. So the stigma that “serious” photographers have historically attached to using the Auto ISO setting should really be laid to rest.
That happy development allows us to use a mode called “Manual Mode with Auto ISO,” in which we set the camera’s exposure program to “M” or full manual mode but also enable the camera’s Auto ISO setting. By doing so we can preserve full control over both our shutter speed and our aperture, but also allow the camera to choose the best ISO setting to give a good overall exposure as lighting conditions change. Making this mode even more appealing, most cameras let us select the highest ISO setting (say, 6400) that we’re willing to allow. So if the lighting level gets sufficiently dim, the ISO won’t go so high as to introduce a lot of noise into the image; instead, we just select a slower shutter speed and/or a wider aperture.
A good example of when it makes sense to use Manual Mode with Auto ISO is when shooting a street fair or an outdoor sporting event. In these situations the lighting can change quickly depending on the cloud cover, what direction we’re shooting, and the subject and type of image we’re making. The following three images were all shot at this year’s Carnaval San Francisco, a big street festival and parade. It was a sunny day, but much of the parade route was in open shade, and depending on the subject there were times when I wanted to use some fill flash. To freeze the motion, I needed a fast shutter speed, and to isolate my main subject I usually wanted a wide aperture. Using Manual Mode, I could choose both of these settings. But because the light conditions were ever-changing, coupling the use of Auto ISO with Manual Mode allowed the camera to adapt the exposure to the light levels for each image.
Full direct sunlight on the main subject made for very bright lighting. Buy this photo
Open shade with a touch of fill flash required slightly different settings. Buy this photo
A close-up portrait made in cross-lighting needed yet another exposure level. Buy this photo
The next time you’re shooting in a shifting lighting environment yet also want to preserve full control over both shutter speed and aperture, try Manual Mode with Auto ISO. It’s not covered in most cameras’ instruction manuals, but it can be a big problem-solver in many situations.
Do you use Manual Mode with Auto ISO to control exposure? Do you have other tips for how to adapt to changing lighting conditions without handing over the creative control to your camera? Please share your experiences here.
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