Manual Mode + Auto-ISO

In Apperture Priority Mode, I can control the Aperture and ISO. The camera sets the shutter speed automatically.

In Shutter Priority Mode, I can control the Shutter and ISO. The camera sets the apperture automatically.

In P Mode, I can control the ISO. The camera sets the shutter speed and aperture automatically.

Seems like there are a few possibilities missing. Actually half of them are missing, but we can access them by turning on Auto-ISO. Take a look at the following chart to see the extra possibilities this provides us with:

Exposure modes with Auto-ISO

Of special importance is the way turning on Auto-ISO affects the Manual Mode, which actually ceases to be fully manual. In fact, according to Ken Rockwell this is a firmware defect and it seems the trick works only on Nikon cameras. What Ken fails to realize is that there are certain benefits of having manual control of the shutter speed and aperture, while leaving the camera to set the ISO. I suspect that Nikon has done this on purpose.

SLR Lounge has a very nice article about this. Make sure to watch the video too!

* For Nikon D80 I had to go into the Custom Settings Menu (the pencil icon) to turn on Auto-ISO. More detailed instructions for Auto-ISO on the D80 can be found here.

Locking the ISO in Manual mode (i.e. “disabling” Auto-ISO)

Here is a nice “add-on” to Auto-ISO + Manual Mode: I normally have my AE-L/AF-L button set to AE lock hold (this can be set under the Custom Settings Menu)  which means that pressing the button will lock:

  1. the aperture when in Shutter Priority mode
  2. the shutter when in Aperture Priority mode
  3. the ISO when in Manual mode (they should have called the button AD-L/AF-L/AI-L)

The third point is the one that concerns us right now. Let’s explore this further.

If I had Auto-ISO + Manual mode enabled and I pointed my camera at a very dark subject my ISO would automatically adjust to 1600 (the highest in this camera, though a limit can also be set under the ISO Auto setting). Now if I pressed my AE-L/AF-L button the ISO would remain locked at 1600 even if I pointed at a very bright subject, like the sun.

I’ll probably never use the function in exactly that way, but let’s look at a second/inverse example, which could be very useful:

If I had Auto-ISO + Manual mode enabled and I pointed my camera at a very bright subject my ISO would automatically adjust to 100 (the lowest in this camera). Now if I pressed my AE-L/AF-L button the ISO would remain locked at 100 even if I pointed at a very dark subject.

This would be useful when working with a tripod. Since camera shake wouldn’t be an issue I would like my ISO to be as low as possible. Instead of having to go into the camera’s Menu and turning off Auto-ISO I could instead point my camera at a very bright subject and lock the ISO there before I start the session. If the camera is already perfectly in place on the tripod I could shine my phone’s light (maybe even use a flashlight app) towards the camera to get the ISO I want to lock.

The only problem with this is that it would be virtually impossible to set the ISO to something specific between the 100 and 1600 points. If the camera could show its auto-updating ISO number it would make this a lot easier. It would actually be a useful feature to have in general. By the way I’ve tried manually setting the ISO while I have Auto-ISO turned on and it did nothing. I even tried locking the selected ISO in different ways but it seems that selecting Auto-ISO makes the dedicated ISO button completely obsolete.

Leave a Reply

Your email address will not be published. Required fields are marked *