Canon Auto ISO with exposure compensation

[John Chardine]

With the excellent ISO performance of modern cameras, people are making use of Auto ISO more and more. The idea is to set exposure mode to manual, set the desired shutter speed and aperture, then set ISO to auto. So say you needed 1/1000s @f5.6 you could guarantee those settings in different lighting conditions and have the camera adjust the ISO. Even though you have set the camera to manual mode, this is an automatic exposure setting and as such it would be useful to set an exposure compensation, say +1ev or whatever. Nikon cameras allow this but Canon does not. This issue was discussed here, with a story that Doug Brown contacted Canon about this and the answer was that Canon did not have the capability:

http://www.birdphotographers.net/forums/showthread.php/102359-High-ISO-Performing-Bodies-Why-not-Auto-ISO

True enough but there is a solution for folks who can limit the range of SS and aperture in menu (like you can on the 1DIV)- had a brainwave this morning! It's a bit of a kludge but it does work.

1. Set your exposure mode to Av or Tv.
2. Go to C.Fn 1: Exposure menu 12 and Enable SS range, then Register your highest and lowest SS to what you want.
3. Go to C.Fn 1: Exposure menu 13 and Enable aperture value range, then Register your highest and lowest aperture to what you want.
4. Set auto ISO.
5. Set your exposure compensation as usual.

I am not sure how many other Canon bodies allow you to set the range of SS and aperture but I assume the 1Dx does and probably also the 5DIII.

Give it a try!

PS I guess as Doug found out, the 5DIII cannot do the above.

[Dan Brown]

Good work, John! So, EC is only available when the limits are set? Can you just, for example, set auto ISO while in AV and have EC? Either way, with the high end Cameras, this is a nice option at times!

[John Chardine]

Hi Dan- You can set auto ISO while in Av and have EC set but as you change EC is varies aperture and ISO, which could work for some situations- fix the SS and have the aperture and ISO change. You could put a limit on the aperture so that your lens of choice is always shut down a little but doesn't shut down too much.

[Blake Cook]

<embed id="application/x-exifeverywhere" type="application/x-exifeverywhere" width="0" height="0">Hmm.. I just assumed that's how everyone used Auto ISO. It works on 5D3, 1Dx and 1DIV.

[John Chardine]

Blake- the key point here is being able to dial in exposure compensation with auto ISO. Nikons allow this but Canons don't directly.