camera button friday: the button i wish i had

On Nikon and Canon cameras, there are two scroll wheels that a photographer uses to control exposure: the shutter and the aperture scroll wheels. But now that our cameras have great ISO performance, ISO has become the third variable in exposure. (Here comes the rant, are you ready?) I want a third wheel for my ISO control. I have a dedicated button on my camera but I can’t quickly change it like I can my shutter or aperture. Before you Canon guys let me know that your ISO button is up on the right side and easy to get to I will tell you….yes it is, but not as easy as I would like.

So, can I get another scroll wheel? Or at least a button that I can grab easy (like that custom 'Fn' buttons already on the front of my camera) so that I can press and hold them while a scroll with one of the wheels to change ISO?

[end of rant]