What is Base ISO?
Base ISO (some call this Native ISO) is the setting where you get the most quality your camera can deliver.
At the Base ISO, the information recorded by your sensor is not electronically amplified in some way, so you get the cleanest signal your camera is capable of capturing. Base ISO also gives the best dynamic range, which means you can capture the widest range of brightness, from light to dark.
Using the Base ISO offers significant performance advantages, so it is important to know the Base ISO for all your cameras.
Base ISO is where your sensor will perform at its theoretical “best.” But surprisingly, this value isn’t listed in the specs on camera manufacturer’s websites. It also isn’t necessarily the lowest setting your camera allows. Some manufacturers even allow you to set an ISO that is lower than the Base ISO and that can have “interesting” outcomes.
So how do you find the Base ISO for your camera?
As wrong as the internet is on most things, searching for your camera’s Base ISO will usually get you the right result. DPreview.com seems to do a good job of this.
If you are looking for a little more technical way to determine Base ISO, then you’ll want to check out the dynamic range chart at photonstophotos.net (https://www.photonstophotos.net/Charts/PDR.htm). It takes some effort to learn to read this chart, but it can provide useful insights, and I find the information matches with my experience across several cameras I’ve used.
To make it easier for you to find the Base ISO of your camera, I’ve created a chart of the Base ISO of some popular cameras, using the chart at photonstophoto.net. If you find an error in this list, please let me know.
Base ISO List
ISO 64
Nikon D810, D850, Z 7, Z 7II, Z 8, Z 9
ISO 100
Canon EOS 1D MkIV, EOS 1Ds MkIII, EOS 5D MkIV, EOS 6D MKII , EOS 7D MKII, EOS R5, EOS R6 MkII, EOS R7, EOS R8
Fuji GFX 100, GFX 100S, GFX 50R, GFX 50S, GFX 50S II
Nikon D5600, D600, D750, D780, D800, Df, Z50, Z6 II
Sony A1, a5000, a5100, a6000, a6100, a6300, a6400, a6500, a6600, A7 III, A7 RII, A7 RIII, A7 RIV, A7 RV, a7S III
ISO 125
Fuji X-T5, X-H2
ISO 160
Fuji X-T4
ISO 200
Fuji X-A5, X-E3, X-T2
Olympus OM-D E-M5 MkIII