I found a nice quick setting adjustment for the 1DX that I would like to share!
Lets say you're shooting a stationary subject and then you want to quickly change your shooting mode and settings for a moving target. I have my M-Fn2 button set to switch between One Shot and AI Servo, but lets say that you want to quickly change all of your settings for a Bird in Flight Burst, without switching to a Custom Shooting mode, which has a few extra button presses.
Take a look at C.Fn5 Operation Menu, choose Custom Controls, then scroll down to AE Lock* Button, press Set scroll down to the "Camera Icon" and press "Info Button." Now you should be in Register/recall shooting functions and choose the settings that you want.
After you've finished with your selections, it's a bit confusing and it looks like you have to press Register Current Settings for these new settings to take affect, however, that button refers to the settings that are already currently set in the camera and not to the new registered choices that you have just selected above. So, just press menu when you're done
My settings are:
Shooting Mode: Manual
Shutter Speed: 1/1250sec
ISO Speed: Auto
Metering Mode: Evaluative
White Balance: AWB
AF area Selection mode: Manual Select Zone AF (a quick press of the Multi-cont brings you back to center)
Tracking Sensitivity: 0
AF pt. switching: +2
Servo 1st img priority: Equal
Servo 2nd img priority: Equal
AF start postion: Manually selected AF point
AF operation: ON
Some people may also like full 61Pt. AF area selection, but I have found that it can still miss smaller birds in flight, even in a clear sky but I'm still experimenting with the settings.
These Registered settings may be recalled from; P, AV, M,TV, and Bulb believe it or not, as well as from C1, C2, or C3 as far as I can tell.
Two settings that I noticed it doesn't have is for AI Servo and High Speed Continuous, which I'm always in when I'm shooting action. So also be aware that if you have One Shot and Single shooting selected in AF Drive mode, then you won't get a tracking burst, you'll just get one shot. If this ever happens by accident then obviously just keep pressing the shutter button while holding in the AE* lock button, if the action continues, then you may need to press AE* to re-lock focus as your subject distance changes. Personally, I would like to see AF Mode and Drive Mode added to these Custom Recall Settings. Don't worry, I'm making a list that I will send to Canon!
I also have ISO Safety Shift on by default so I don't blow out the sky when I'm using a fixed ISO, but when shooting in Manual, Auto ISO in Custom Controls above should also alleviate that problem!
Once you're done, and then you press the AE LOCK* Button you will be switched into your new settings as long as you continue to hold in the AE button*. The AE button also Auto-focuses so you just have to press AE* and shoot with the shutter button. I use AF-On for my default Auto-Focusing and not the shutter button, but even if you use the Shutter button to focus, once you press the AE* lock to recall your new shooting settings, the AE* button will also lock Auto-focus so that you won't re-focus on your subject when you press the shutter button to shoot.
Once you release the AE Lock* button you will be returned to your previous camera settings. I think it's great if you're shooting a stationary bird in AV mode and then all of a sudden a BIF or Big Foot comes along, and you have to quickly change your settings.
I hope the 5DIII has this feature too, hopefully someone can check and let us know!