40D "AF-ON" button?

Grimm75 wrote in post #3813906
I guess I'll have to figure that one out then! Thanks!

Set custom function 4, to 1

bildeb0rg wrote in post #3814187
Set custom function 4, to 1

Or 3, depending on when you want the metering to be locked. 1 if you want exposure to be locked as soon as you press the shutter button (i.e. half-press) or 3 if you want it locked just before the picture is taken.

so AF-ON purpose is to focus something right? ... How is that different from pressing shutter half way down? I'm still a bit confuse ..

nice!

MCSboy wrote in post #3817831
so AF-ON purpose is to focus something right? ... How is that different from pressing shutter half way down? I'm still a bit confuse ..

It seperates locking the focus AND exposure which is what you get when you half press the shutter. Particularly useful if a subject is moving within variously lit areas, like a bird in flight from sun to shadows.

PacAce wrote in post #3814807
Or 3, depending on when you want the metering to be locked. 1 if you want exposure to be locked as soon as you press the shutter button (i.e. half-press) or 3 if you want it locked just before the picture is taken.

As he wants to split the focus from shooting, I figured there's no need to half depress the shutter button.

Since the " * " separates the focus from the shutter button, is there any advantage to using the "AF-ON" over the * ?

Southswede wrote in post #3819160
Since the " * " separates the focus from the shutter button, is there any advantage to using the "AF-ON" over the * ?

The only advantage I see is that when using a speedlight the * button will fire off a test flash and lock the flash exposure.

Whereas before that feature would be lost to the * button doinf AF.

So this was you have the shutter button to lock exposure, AF-ON button to focus and * button to lock flash exposure.

This is cool. I always shoot with the focus button on the "*" all the time. Cant wait for it to arrive.

The AF on button is also used to adjust/turn on the focus when using live preview as its not a continuous focus.
so have any of you got the 40D to test out whether it can be used like the * button on the 30D?

bildeb0rg wrote in post #3819133
As he wants to split the focus from shooting, I figured there's no need to half depress the shutter button.

I was talking about pressing the shutter button, either half-pressed or fully, to lock the exposure, not focusing. Both settings moves focusing to the "*" button. The difference, though, is when the exposure is locked. With 1, the exposure is locked as soon as the shutter button is pressed. WIth 3, it is locked just before the exposure is made. There is a subtle difference between the two. When shooting a burst of frames, one will use the same exposure for all the frames. The other will meter the exposure before each frame.

The AF-On button also works in Live View -- it drops the mirror momentarily so that the camera can use its AF sensors.

Hi,

Yes, I think Canon was smart adding the AF On button. They must have noticed how many people were using CFn 4.

I use CFn 4 - 3 when shooting in One Shot mode, but usually switch back to CFn 4 - 0 when shooting AI Servo. I have never been able to master the skill of pressing both the shutter button and the * at the same time. Maybe the AF On button will work better for me.

Anyway, nice move Canon... Now can we chat about that "Print" button and Mirror Lockup?

Southswede wrote in post #3819160
Since the " * " separates the focus from the shutter button, is there any advantage to using the "AF-ON" over the * ?

In case it wasn't obvious from the other posts, you can't directly assign the "*" to focusing on the 40D like you can with the previous models via C.Fn-04 because the AF-ON button was set up specifically for that purpose. But, what you can do is swap the functions of the "*" and the AF-ON buttons so that you still use the "*" for focusing, instead of the AF-ON button, on the 40D if you've gotten using to use the "*" button.

dave_bass5 wrote in post #3825390
The AF on button is also used to adjust/turn on the focus when using live preview as its not a continuous focus.
so have any of you got the 40D to test out whether it can be used like the * button on the 30D?

Yes, it can.