The Pros and Cons of Auto ISO
For the last year and a half I’ve been shooting using Auto ISO setting on my camera. But in the last month or so that’s changed and I’m shooting using a fixed ISO more and more. In truth there are benefits and disadvantages to using AUTO ISO. This was something that I really appreciated from going shooting with Oliver Krumes in Berlin who also used the Fuji X100t but set his exposure manually. So I thought I’d reconsider and go over the pros and cons of shooting with Auto ISO again. That way I’d help clarify my own thoughts and perhaps help you too.
You can easily deal with radically changing light
One of the main reasons for using auto ISO is that you can easily cope with radically changing light. If you want to change between shooting through a cafe window to shooting a market square, having auto ISO helps you make those rapid changes while not fiddling with any dials or having to work out how many stops you need to add/take away.
This helps you capture more moments than you would without using auto ISO. Of course, you could using aperture priority mode or shutter priority (or just fully automatic) but…
You don’t mess with the style of the photo you want
Your aperture and shutter speed are vital for the “style” of photo you want to take. The difference between a shallow depth of field and short shutter speed compared with a deep depth of field and a long shutter speed is huge. As are any of the other variations in between.
By using auto ISO, you can (to some degree) set the style you want and then let the camera adjust the ISO to keep that style. Of course, at high ISO you’ll get more noise and grain which does affect the style of your images, but most cameras are shockingly clean until around 1600/3200 or higher. You can also add that grain in post production, but you can’t shorten your shutter speed after the fact…yet.
You can “set it and forget it”
Linked in with these two points, you can set your settings and then just forget about them and focus on the world around you, letting your camera get the exposure…alright. This really helps you to just focus on the photos and nothing else.
All in all I think those are three pretty good reasons for using Auto ISO when you shoot and they were the main reasons that I used Auto ISO. But recently the cons have been pushing me the other way.
If you want to shoot flash on the street, you’re probably going to need to set things manually. You can use TTL settings (well if your camera and flash support it) but knowing how to set things manually helps to avoid issues of the autofocus searching for people (and a delay in the flash firing) or having issues with the ambient light.
If you understand how your flash works and can set things manually, then you can quickly take good looking flash images on the street.
Shadows and shafts of light
If you really want to take photos of shafts of light, your camera will probably let you down. It wants to try to balance the histogram and so will try to boost the shadows. This will overexpose the subject in the shaft of light you’ve found. Instead, if you can get your exposure set up (and fixed) right manually, then you’ll have deep shadows and perfectly exposed shafts of light.
Understanding the light
Building from that last point, in general, understanding the light around you will help you take photos that your camera would never think of taking. For example, if you know the ambient exposure on the street and have your camera set for that then you’ll know that when you enter that tunnel, the light on the street at the end will be perfectly exposed. In contrast, you’ll also know that as you adjust for the alley, how many stops over exposed the street will be and what that will look like.
This is something that I’ve really found from shooting film. It really teaches you to be aware of the light around you and makes you more aware of your settings. This helps you stay more prepared for shots and to even pre visualise the shot that you can get. Sure, you can use your LCD or EVF to get a similar effect (and sometimes this is essential with things like darkened car windows) but if you understand the light and get your camera ready for that, you’re already a step ahead.
I think I’m going to switch to setting my ISO manually (suddenly the x100F’s ISO dial sounds a heck of a lot more appealing). It fits the more Film like experience I have been seeking and yet still lets me use the AMAZING Fuji X100t (yup, I’m back in love with this camera after an awkward, cold January of shooting film.)
About Chris Wilson
I'm an English as a Foreign Language teacher in Krakow, Poland in my spare time I love taking photos. This is my blog.