A/E-A/F button and its complexities

[jim silva]

Ive got a bit of a puzzler for me in the A/E,A/F area. When yrying to recompose a shot, and all you ever get from the manuals , ect, is "point to a brighter area of the sky, hold the A/E-A/F button in and go back and recompose the shot and shoot." The problem I'm concerned of is what about the focus in that area that you just froze while using the A/E-A/F button? In the default mode settings both are set to automatically set your focus and exposure when you depress your shutter halfway. OK, but I have tried this to an extent, and more and find occasionally will get an out of focus shot by doing so. I am aware of the individual settings you can set the A/E-A/F modes in, but what happens to one or the other(exposure/focus) when you set that in such way? In other words, the shutter seems to be a two-fold tool. When and how do you control both? Another example is the flash value setting when used for situations, now the A/E-A/F button cannot be used if you wanted to recompose a shot?
Can someone/someones help clarify this demon of mine?

[pippin88]

I always wondered what that button was for?

I'd also like to know if you can use to it to lock exposure but not focus. For using spot metering, it would be handy.

[MHD]

In the menus you can change the function of the button...
and yes 99% of the time I used if for spot metering...

[digitor]

The default mode is that the shutter half-press locks the focus, and the button locks both. Meaning that you can hold focus with the shutter button, then meter another area, push the ael/afl button which locks exposure and focus, then recompose and take the shot. Focus doesn't change, I use this method a lot.

Cheers

[Onyx]

IMHO this is one of the main shortcomings of the D70, compared to Nikon's pro bodies.

You can program the button to perform a function from a myriad array of choices, but you can ONLY have it do the one function at a time.

If you don't like the way the defaults are programmed, have a play with these options and see how they affect your shooting.

Also one pleasant side effect of the programmability of this button is that you gain an undocumented 'feature' on the D70 - that of "trap focussing".

[mudder]

I've wlays found it handy to use the AE/AL to set focus, I find it handy to set focus on my subject, keep the focus as set holding the button, then I can meter on what-ever I want and re-compose...

[Deano]

I've wlays found it handy to use the AE/AL to set focus, I find it handy to set focus on my subject, keep the focus as set holding the button, then I can meter on what-ever I want and re-compose...

I've also started doing this. Got the tip from a C@n*n 20d user. The button is in a much better place on the 20d. I find the placement on the D70 means I have my thumb nuckle in my eye (I use the left eye at the viewfinder). I'm still getting used to having to lock focus and sometimes I forget and can't figure out why I'm OOF.

Cheers
Dean

[jim silva]

Thanks for all replies folks. Much appreciated. I guess I'll set the AE/AF but on Focus only and recomp the metering stuff with half shutter... then recompose... see how it works for me.
Jim

[Aussie Dave]

I've wlays found it handy to use the AE/AL to set focus, I find it handy to set focus on my subject, keep the focus as set holding the button, then I can meter on what-ever I want and re-compose...

Hi Mudder
forgive me if I am incorrect, however isnt this the same as "half-pressing" the shutter release button ? Can you not half-press until focus is locked and confirmed, then re-compose your shot and shoot ?

Just curious if there is a difference in using the AE/AF-L button as opposed to the shutter release, for the purpose you described......?

[mudder]

I've wlays found it handy to use the AE/AL to set focus, I find it handy to set focus on my subject, keep the focus as set holding the button, then I can meter on what-ever I want and re-compose...

Hi Mudder
forgive me if I am incorrect, however isnt this the same as "half-pressing" the shutter release button ? Can you not half-press until focus is locked and confirmed, then re-compose your shot and shoot ?

Just curious if there is a difference in using the AE/AF-L button as opposed to the shutter release, for the purpose you described......?

G'day Dave,
I just find it handy to be able to focus on one thing (using the af lock button) and THEN meter using a half-press on the shutter on something else (like a highlight somewhere). This way I can focus on one thing, and then set the metering on something else in the frame, that way I can set the shutter to avoid blowing out the highlights that are elsewhere in the frame... Using the shutter for both means the focus and meter are set at the same time/location...

Cheers