There are not a lot of things that bug me about my Fujifilm cameras, but auto ISO is one of them. How they have not fixed this is a mystery so I am going to go on a rant here.
The issue? How exposure lock, or lack there of interact with ISO and AF-C.
By default Fujifilm shows you Max ISO on your screen if you’re in a AUTO ISO mode. If you press the shutter, you see actual ISO. Great? No, great if you want to lock the exposure when you press the shutter, terrible if you do sports or anything where the exposure is likely to change from the moment you first start autofocus until the moment you take the last picture.
Let’s take a hypothetical situation. You’re following an athlete who is travelling around a track focusing on him until that moment he reaches a certain point where you want to take the photo. If you start focusing on him when he running in a light area, you photo will be underexposed, if you start focusing on him when he is running in a dark area, you’re photo will be overexposed.
That’s the purpose of exposure lock obviously, so that seems to be working as planned so why the issue?
In the above scenario you would want to turn off exposure lock and that’s where the problem comes up? Exposure lock is a lesser used scenario, you almost always want exposure to adjust continually for changing conditions. Switch off the exposure lock and you never see actual ISO. Yes, you just get to see the max ISO all the time, even when you hold down the button. If you take a photo, there is no way to see how high the ISO is going so you can keep track of it, without actually stopping, and checking what the ISO was on the last photo.
The problem with this approach is the lack of consistency as Fujifilm works different with AUTO shutter. Use a fixed ISO and auto shutter and with exposure lock off it will show you the actual shutter all the time. Move your camera around and you get a live reading. Again, why Fuji chose to show me my max ISO is a mystery. Who cares what I can go up to, I want to know what I am at now, not what I set the max to.
For now, my solution is to progressively raise the AUTO ISO from 800 to 3200 to 6400 as conditions require it, but it’s a fix to a problem that is easy to fix and simple shouldn’t be there.
How do you reproduce this problem?
Set your camera to AF-C, AUTO ISO with a fixed aperture and shutter. Focus on something light and without letting go of the shutter move to something dark (you will see the actual ISO) and take a photo. When you press down the shutter to start focusing on the first object, the exposure will lock at that point. The photo will be completely underexposed because it will have locked the exposure on the original object.
Now switch off exposure lock on the shutter and press the shutter. No matter where you focus, you never see the actual ISO, just maximum. Why should a lack of exposure lock prevent you from seeing the current ISO? I have no idea.
Now switch on auto shutter and you’ll see the shutter constantly changes when you move the camera around, before you press the shutter.
What about reporting it?
I have reported it to Fujifilm. I reported it when the X-T2 was released and nothing.