I didn’t know what the ‘Auto Lighting Optimizer’ did so I tested it.
In the first found of tests I didn’t see that much difference with the fan. However on the ‘Strong’ setting I could see the text in the middle of the fan a little bit better. In the second round the strong setting again provided a noticeable difference in my face in contrast to my black jacket.
I didn’t see any noise issues at this lighting level, I mostly saw a difference in brightness. I will have to try testing this at night sometime.
I think I will leave it on ‘Standard’ for my photography and ‘disabled’ for my videos on the T2i.