Annoying firmware "feature"

[khaksnes]

I have discovered an annoying bug in firmware 1.2.3 for 5D MK iii.
I am trying to set up a custom mode to allow me good control and at the same time reasonably fast and safe operation. My custom mode is based on Av, Spot metering and focus only with AF-ON button. * button is set to exposure lock M-Fn to electronic level.
My intention is to focus, set aperture, measure light, if intended correct exposure, finally compose, checking the leveling as part of composing if appropriate.
The problem: Pressing the M-Fn button cancel the exposure lock.
Do anybody know about a workaround or who to contact in Canon to get this fixed in a future firmware release?

 

[Marsu42]

Do anybody know about a workaround or who to contact in Canon to get this fixed in a future firmware release?

There is the official Canon U.S. forum, best report it there - people had success after insisting that the af assist light is buggy, and Canon fixed it a firmware update: http://forums.usa.canon.com/

 

[Mt Spokane Photography]

I have discovered an annoying bug in firmware 1.2.3 for 5D MK iii.
I am trying to set up a custom mode to allow me good control and at the same time reasonably fast and safe operation. My custom mode is based on Av, Spot metering and focus only with AF-ON button. * button is set to exposure lock M-Fn to electronic level.
My intention is to focus, set aperture, measure light, if intended correct exposure, finally compose, checking the leveling as part of composing if appropriate.
The problem: Pressing the M-Fn button cancel the exposure lock.
Do anybody know about a workaround or who to contact in Canon to get this fixed in a future firmware release?

Press M-Fn first to level the camera, then the * button?

It does sound like a minor bug. You can report it to Canon, but unless its giving a lot of users a problem, they will likely not change anything. Firmware is so complex that a minor fix can cause a major problem, so they are reluctant to change firmware.

 

[khaksnes]

Leveling first doesn't work unless the area to be metered is in the center of the picture, in that case the locking of the metering isn't needed.
The main reasons for using of the leveling is horizons particularly in wide angle pictures, or to ensure good alignment for verticals. This must be done after composing the picture, at that point the spot metering area is likely to be of the area I intend to measure, if it isn't then I don't need to lock it.
The bug might be easy or hard to fix depending on how the firmware state machines is coded.
(I have been doing a fair amount of firmware development myself in an earlier job but not for cameras.)
The end result is that exposure lock and electronic level are at the current time mutually incompatible features, if you need to use both you are out of luck.
It is possible to go to Manual mode, turning off Auto ISO and work from there, then there will be no need for the exposure lock. The problem with this is that the workflow is slower with a bigger risk of operator errors.