Think about using Auto-ISO in your digital camera
... and combine it with manual focus for a street photography secret weapon.
These past days I've been shooting more digital than film. Part because it's winter and color sucks, part because it's cheaper, part because I want to save my film energy for the spring.
Digital brings convenience, and one of the most underrated ones is the Auto ISO setting, available on most cameras, which is something I’ve been using more frequently recently, so in this post, I’ll describe some thoughts about using this feature.
Most (if not all) digital cameras allow you to do full-auto, Av, and Tv. Av as in Aperture Value, and Tv as in Time Value. I'm using Canon nomenclature because that's what I started with, but these terms vary according to the manufacturer.
We all know the exposure triangle is made of Aperture (f/), Shutter Speed (s.s.) and ISO.
In summary, Av is when you set the aperture and ISO, and the camera calculates the shutter speed. Tv is when you set the shutter speed, and the camera calculates the aperture — all for the exposure to be set according to what you define in the Exposure Compensation, which is typically set to 0 EV.
PS: Av is only available on cameras that are able to electronically set the aperture on the lens, or cameras that are a mechanical marvel, so among all these modes, it's the most “expensive” one.
Something oftenly underlooked is the Auto ISO, where you set the shutter speed, the aperture, and the camera changes the ISO to satisfy the needed exposure. Something that got later introduced in digital cameras, because it's not a possibility with film.
Turns out, this method benefits street photography by a lot, because you can set a fairly closed aperture (like f/8), configure a manual focus lens to focus everything in between 1.5m-4m, set a shutter speed where you are sure there won't be camera shake (like 1/250 s.s.), and let the camera increase or reduce the ISO automatically for a well-exposed scene (according to the metering mode).
Ideally, on digital cameras, we would like to use the ISO as lower as possible to reduce noise and increase dynamic range, and luckily, most cameras allow you to set up a maximum ISO setting for the Auto-ISO, while also setting a 1/f minimum shutter speed to avoid camera shake. Let me explain, because this isn't so intuitive as it looks…
As you can see, in my M10-R, I have it set as 1600 for the max ISO, while respecting 1/f of a shutter speed. That said, the closer the aperture, the faster the shot tends to be.
For example: Let's say I set f/4, the maximum exposure time would be 1/4 sec.
In the same scene, if I set f/8, less light would be coming in because I am closing the aperture, that would make the camera to lower the shutter speed, but that could introduce camera shake, that's where the 1/f thing comes in.
In this case, the rule of 1/f would assume, making the maximum shutter speed 1/8 sec (in case of f/8), that would make the ISO go up, sacrificing digital noise rather than resulting in a blurry image.
Turns out that digital cameras nowadays do a very decent job on everything below ISO 3200, and if you have a Monochrom camera, these values can go up to ISO 64000 without a noise disturbance.
These settings are pretty much smart!
Here are some shots I took using this method. It's easy because I don't need to concern with focus, as my f/ is usually fairly closed for zone-focusing.
What are your thoughts? When you're shooting digital, do you usually use semi-automatic modes? Do you go full manual? I usually keep alternating between different methods, but I want to know about how you do!
I started using auto ISO with underwater photography. Once I discovered how helpful it was, I started experimenting on land, too. I usually add some exposure compensation as I prefer to ETTR, but it's definitely a handy feature!
Unless I’m doing long exposures or other tripod work, I almost always have my camera set to auto ISO (with a limed upper end). It’s a very handy feature.