5D Mk III customization question

[Dave_NYC]

I may eventually get to this answer on my own (reading the manual and a couple of other documents/books on the 5D Mk III) but have an event next week and am trying to figure out what the fastest way to change manual flash output level from the camera is (i.e. 1/1 - 1/128).

I tried the Flash exposure adjustment (doubles with the ISO button then use the quick dial) but that only affects TTL flash, not the manual setting. So far, if I want manual flash and adjust my light output from the camera, I have to go to external speedlite control. Quickest method of getting to that I've found is assigning it to the top slot in My Menu.

Is there a way of assigning a single button so I can jump directly into external speedlite control?

I am using a 5D Mk III, YN568EX and YN622c transceivers, if that matters.

[neuroanatomist]

Not that I know of...I think My Menu > External Speedlite control is your best bet.  But, I think that a specific manual output set that way is stored as a C# setting. If so, you could possibly establish identical settings for C1-C3, but with manual flash output set to 1/1, 1/16, and 1/128, for example. Not very fine control, but fast to turn the dial.

[RC]

Not that I know of...I think My Menu > External Speedlite control is your best bet.  But, I think that a specific manual output set that way is stored as a C# setting. If so, you could possibly establish identical settings for C1-C3, but with manual flash output set to 1/1, 1/16, and 1/128, for example. Not very fine control, but fast to turn the dial.

It's what I do

[Dave_NYC]

Not that I know of...I think My Menu > External Speedlite control is your best bet.  But, I think that a specific manual output set that way is stored as a C# setting. If so, you could possibly establish identical settings for C1-C3, but with manual flash output set to 1/1, 1/16, and 1/128, for example. Not very fine control, but fast to turn the dial.

That would work. Thanks!