Canon Custom Function 04

Two Questions regarding Canon DSLRs (in particular the 20D):

a) Is it necessary to set the Custom Function 04 to 1 (AE Lock / AF) in
order to use the full time manual focus feature of most USM AF actuator
fitted Canon lenses? (If AF lock is on the shutter can you not use full time
manual focus because the AF algorithm is fighting the manual changes - I
don't know)

b) If you set Custom Function 04 to 1, what happens about FE lock? Does FEL
still occur on the * button or on the shutter release (along with AE lock)?


Cheers


Lester

Lester Wareham wrote:

Two Questions regarding Canon DSLRs (in particular the 20D):

a) Is it necessary to set the Custom Function 04 to 1 (AE Lock / AF)
in order to use the full time manual focus feature of most USM AF
actuator fitted Canon lenses? (If AF lock is on the shutter can you
not use full time manual focus because the AF algorithm is fighting
the manual changes - I don't know)

Exactly. If you leave CF4 on 0 and adjust the focus manually and then
press the shutter release, the AF will adjust to what it thinks is
good. So the first thing I did on my D30 and now on the 20D is to
program CF4 to either 1 or 3 (difference comes below)

b) If you set Custom Function 04 to 1, what happens about FE lock?
Does FEL still occur on the * button or on the shutter release (along
with AE lock)?

The * button then is for the AF only and the shutter release is for AE.
If you set CF4 to 1, the the shutter release will work as AE lock (Tv,
Av, P mode, of course not M, does anybody use the other settings?). Aim
at some dark areay, half press the shutter release, keep it down and
turn the camera to some light area and watch the displayed values for
time and aperture. They will stay at the values of the dark measuring
point. That AE lock and is indicated by the '*' in the viewfinders
display.

If you put CF4 to 3, then AE is not locked. Do the same as before and
you will notice that time and aperture are adjusted while turning the
camera. This is great if you are following some moving object, i.e. a
car that is passing in front of light and dark backgrounds.

So if you need AE Lock, use CF4-1, else CF4-3. You quickly get used to
have AF on the * button. BTW, on the 20D, I now use mostly the AF as
it's excellent working even in quite dark surroundings, on the D30 it
was often necessary to use the FTM of the lenses as the D30's AF barely
deserves it's name.

Greetings
P.J.

--
Peter-Josef Meisch

Lester Wareham wrote:

a) Is it necessary to set the Custom Function 04 to 1 (AE Lock / AF) in
order to use the full time manual focus feature of most USM AF actuator
fitted Canon lenses?

Do the AF lenses you own/use not have an AF on/off switch on
the lens? That would be much faster ...

-Wolfgang

Wolfgang Weisselberg wrote:

Lester Wareham wrote:


a) Is it necessary to set the Custom Function 04 to 1 (AE Lock / AF) in
order to use the full time manual focus feature of most USM AF actuator
fitted Canon lenses?


Do the AF lenses you own/use not have an AF on/off switch on
the lens? That would be much faster ...

Not if you alternate between MF/AF regularly, or want to switch over
quickly on a here-and-gone shot. Relocating AF to * instead of
half-pressed shutter lets you MF and force AF on-the-fly without the
camera second-guessing every time you push the shutter. Personally, I
think I'd find it useful shooting small objects on a plain background
like... model flying planes... I just get a focus, and the camera
decides to refocus if the plane strays off the focus points just a bit,
and buzzes all over the place trying to lock on to the sky...