This morning I was playing around with my D7100 and 16-85mm. I have the AE-L/AF-L button programmed to AF-On only. To my surprise, when I focused my shot by pressing the AF-On button, I heard the distinct sound of the VR engaging. I then attached my 70-300mm and got the same results. I thought that VR only engaged when you pushed the shutter release button (at least that's the way I remember it working on my other bodies). I don't recall Nikon changing this feature on the D7100?
No, there isn't such an option. It was added, I presume because the higher res cameras needed the aid in AF with a stabilized image on the focusing sensor but it also has the advantage of a stablized VF for the user's benefit also. The battery life should not be affected very much, a lot less than say, auto preview. The D7100 and D7000 are quite thrifty in their battery usage, something I am reminded of every time I pick up my D800 which is not. Stan St Petersburg Russia
So, to further clarify Stan, you're saying that the VR is automatically activated with the D7100 when the back button is used to focus also, all in one step sort of.
I do note as you and another stated, that when the back button, set to AF-On, is used to achieve focus in cameras such as the D7000, VR is treated as a separate entity by engaging only when the shutter button is pressed...Is my understanding of this correct? I certainly prefer how it works in the D7100 than the way it's set up in the D7000 and other previous cameras. Sort of nice to see the image settle down before you actually press the shutter, I think.
Yes, using AF-On, the D7000 and D7100 treat VR differently and future cameras will surely follow the D800/D4 method where it was introduced. The D600 and D7100 followed. I like it on the D800 and do not mind its possible impact on battery life. Stan St Petersburg Russia