I use ae/af-l set to af-on and fn set to ae-l. For me it works better than having two thumb buttons close together like on the d3/4 and d800. Using the thumb and index finger controlling both essential controls at the same time without taking my eye from the vf is perfect......for me anyway. I set all my cameras for that even the d800 Stan St Petersburg Russia
Stan, when are you using ae-l? not in MM, right? I can see it needed when spot metering is used, but current cameras does the spot metering on the AF sensor selected. I do not see value of ae-l, but again, I might did not encounter a situation when it will be useful
I wonder what advantage there is in programming the AE-L/AF-L to AF-ON. I do not have a D7000/ D7100; either, I have a D5100 that I programmed the button for AF-ON. When I press the button, it focuses, but to engage VR, I have to depress the Shutter Release half way. My D200 has a dedicated AF-ON button and it works the same as the D5100. Why not just depress the Shutter Release half way?
Is there some advantage to the AF-ON that I don't know about.
Yes, there are benefits that suit many shooters. By decoupling the AF function from the shutter, and setting the mode to AF-C, you have complete control of focusing for both moving and static subjects and recomposing without starting the focusing process. If shooting a static subject, press the AF-on for the exact focus point needed, such as an eye in a portrait. The most sensitive and accurate focus point is the center cross point. When focus is achieved, release the AF-on button and recompose as you wish, for rule of 3rds or other preference. If the subject has not moved forward or back, focus will still be good, discounting any field curvature. Without any setting change, if the subject moves, AF-C continuous focus tracking is engaged as long as you hold the AF-On button. Both static and active subjects are shot with the AF-C mode. The only disadvantage is AF-C mode does not enable the AF Assist light that is needed at times shooting in very dark conditions. The newer cameras such as the D7100, D600, D800 and D4 are all very good in low light focusing however. There is no need to stabilize the VR by the 1/2 shutter press. I had run tests to see if there is a difference in performance by allowing the system the fraction of a second that a a 1/2 press provides and found that any full shutter release is enough time to settle into the stabilized image. That makes logical sense since the response time of the driven element is so fast that it reacts to minute and fast camera movement due to shake in less time than the 50-60 ms shutter response.
Recomposing means re-metering so having the AE-L function available gives you total control of focus(af-on) and metering(ae-l) without any adjustments or removing your eye from the VF. Locking metering is needed because even in Matrix meter mode that considered the entire scene, it is still biased toward the level under the current focus point so you have the choice of metering on the subject you focused on or another tone level in the scene. It sounds complicated but after short practice it is almost automatic how you determine metering and focus independently from the shutter release. It gives you much more control of how the image looks when captured. Stan St Petersburg Russia
I use the AE-L/AF-L as AE-L only, and use the Function Key as an AF-L. I enjoy separating the AE and AF functions and am trying to get away from the half held shutter before reframing images. I often use Spot metering, so the ability to pick the exact spot for AE is crucial but that same spot is not always where I want to focus.
Just my take on it...Interested in seeing other replies for this one.
I started a later, related, message string on this topic. I use Fn to change crop mode as there is no other way to do this on the camera itself (?). This is important for me to take action shots using the cropped mode. But very soon I will set up my U1 to do action shots so that maybe I can use the fn differently. It seems that action shooting requires so many changes to my normal settings--set to static pictures--that it makes sense to change a dial setting rather than changing: a to s, cropping size, focusing format, etc. Stan seems always to give good advice so I will read what he wrote again after doing the U1 setup. You know, I am worn out trying to learn all these wonerful capabilities! S
Don't have my camera in front of me (and I have only used crop mode sparingly), but I seem to remember using the "i" button (lower left corner of LCD) as a quick way to access shifting back and forth between normal and crop modes. This button, new on the D7100, now gives me more direct access to a lot of things I had previously set up under "My Menu" on my D90.