How do you have your shutter button configured?

[ReneDamkot]

I use CFn4-1 or 3 on my 1D2. Only problem I have, is that in One Shot AF, evaluative metering, AE is still locked for as long as I keep the * button pressed, when using CFn4-3. CPS in the Netherlands are looking in at the problem (for over 4 months now...) Anyone else noticed this?
Coming from Nikon, I couldn't agree more with John_Richard ...

[Eric_Chan]

[ QUOTE ]
Focus with * everytime - I want seperate focus and exposure controls. I have never understood why they never designed it so you can use the shutter release in this way and use the * to lock exposure like you can on Nikon Cameras. Why Canon do you make it impossible to not lock exposure at the point of shutter release?

[/ QUOTE ]

John, if you set CF 4 to a value of 2 or 3, then the Canon body will NOT lock exposure at the point of shutter release.

Eric

[Eric_Chan]

[ QUOTE ]
I use CFn4-1 or 3 on my 1D2. Only problem I have, is that in One Shot AF, evaluative metering, AE is still locked for as long as I keep the * button pressed, when using CFn4-3. CPS in the Netherlands are looking in at the problem (for over 4 months now...) Anyone else noticed this?
Coming from Nikon, I couldn't agree more with John_Richard ...

[/ QUOTE ]

I am not seeing this behavior. On my 1D2, if I set CF 4 to 3, then exposure never locks (regardless of which AF mode I'm in). Strange that your exposure is locking in CF 4-3.

In general, I really like having the body configured with CF 4 set to 1 and CF 18 set to 2. Then I have all AF and exposure possibilities readily available.

- When I want to AF using the center point only, I press X.
- When I want to AF using some a non-center point (or all points), I press *.
- When I don't want AF and instead just want to focus manually, I press neither of the above buttons and instead simply turn the focus ring.
- When I want to lock exposure, I press shutter-release half way.

When I don't want to lock exposure, I set CF 4 to 3.

Eric

[ReneDamkot]

I also use CFn18-2, but use * for center AF point, >< for AFPS.
Could you give this a test please:
Set AF to one shot, metering to evaluative. CFn 4-3, Av or so.
Press * or >< to AF, keep it pressed.
Point the camera at a subject in different light. Look at the exposure set by the camera. release *
Mine locks AE with AF, although the AE lock symbol ('*') doesnt show in the VF. Friend of mine has a 1D2, his camera behaves the same. Photographer I work for has a 1Ds2, same there. 1D and 1Ds I tried: Same. If yours doesn't, I'm *very* curious how to set mine... Thanx.

[Eric_Chan]

Hi Rene,

I just did your test, and you're right. As long as I'm holding down the * or X button (to AF), the exposure is locked. If I let go of the */X button, the exposure unlocks.

Note that the above is true only in One Shot AF mode. When AF is in Servo, the exposure is never locked when using CF 4-3.

I think that if you want completely separate AF and exposure lock controls, then you need to set CF 4-1 in One Shot mode and CF 4-3 in Servo mode.

Eric

[Rick_Corben]

[ QUOTE ]

I think that if you want completely separate AF and exposure lock controls, then you need to set CF 4-1 in One Shot mode and CF 4-3 in Servo mode.


[/ QUOTE ]

Actually, if you want AF and AE lock on independent buttons, I think you need to use C.Fn-04=0 or C.Fn-04=1. As I recall, the behavior does stay constant irrespective of whether the camera is set to one-shot AF or AI Servo.

Unfortunately, from my perspective, C.Fn-04=0 puts the focus function on the "wrong" button. It makes my 1Ds2 behave like a cheap point-and-shoot because it couples AF with the shutter release. I want to make the decisions on focus when and as needed. I do not want the camera deciding and re-deciding every time I happen to press the shutter button. Thus, my preference is to put focus on the *-button which means choosing between C.Fn-04=1 or 3. Unfortunately, neither is a perfect choice.

C.Fn-04=1 simply reverses the button assignment from C.Fn-04=0. Thus, AE lock gets assigned to the shutter button -- again, somewhat like a point and shoot. Most of the time, that is okay. I typically use manual exposure so AE lock has no impact. On the few occasions when I want auto exposure, I can pre-lock the exposure (with a half-button press) or not. Note the behavior is the same for both one-shot AF or AI Servo. And therein lies a bit of a problem. Suppose that I want to use continuous drive mode (i.e., a sequence of exposures). Since AE lock is associated with the shutter button, all of the exposures will be locked to the initial reading. The issue is most likely to arise with a moving subject (e.g., a player in a football game). Sometimes, one wants a constant exposure for a sequence so the pictures line up exactly. But sometimes one wants the exposure to vary as the subject moves from lighter to darker regions. Canon assumes that such a situation is most likely to arise when the camera is in AI Servo so C.Fn-04=3 disconnects AE exposure lock just for that case. In other words, a multi-frame sequence in one-shot focus mode (set with the *-button) will have constant exposure with both C.Fn-04=1 or 3 while a sequence in AI Servo will have constant exposure with C.Fn-04=1 and changing exposure with C.Fn-04=3.

There is some logic to Canon's design, but it hardly qualifies as intuitive or easy to remember. I think I understand it. But who can afford the time it would take to test every possible case and be sure? I regard C.Fn-04 as one of the suboptimal user interface decisions that Canon justifies in the name of compatibility with the past (i.e., past mistakes). It is far from the worst example -- on balance, a minor nuisance.

[ChuckWestfall]

>>In other words, a multi-frame sequence in one-shot focus mode (set with the *-button) will have constant exposure with both C.Fn-04=1 or 3 while a sequence in AI Servo will have constant exposure with C.Fn-04=1 and changing exposure with C.Fn-04=3.<<

Not necessarily.

The issue here is the photographer's choice of metering pattern. When evaluative metering is combined with One-Shot AF and the camera is set to an AE mode, the exposure locks upon focus completion regardless of the Custom Function 4 setting. This has been Canon's design philosophy for the EOS system since Day One with the EOS 650 back in 1987, and it has remained completely consistent through more than 50 EOS models released since then. The idea behind associating AE lock with Evaluative metering is that the main subject is assumed to be aligned with the focusing point when AF is set. This can only occur with certainty in One-Shot AF.

Custom Function 4 provides some flexibility, but it doesn't override the "prime directive" described above. If you want to achieve real-time meter readings that update from shot to shot while the camera is set for One-Shot AF, all you have to do is select another metering pattern such as centerweighted average, partial or spot, then set the camera for either C.Fn 4-0, 4-2 or 4-3.

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