Finding the focus point!..

I know in the canon system, the autofocus sensors and software are in the camera body. Different lenses focus better or worse depending on which body they're attached to. It seems however, that all you have to do is trick the body into thinking a lens has the appropriate electronics and the auto-focus confirm will work for manual lenses. I have an M42 lens with no onboard electronics, and the adapter that I use to attach it to my Canon has a little circuit that simply tells the body that a lens is attached, it doesn't actually communicate with the lens, but that enables af confirm.
 
Do you ever focus and recompose? If the camera locked on to 2 points, and then you recomposed the shot before you clicked the shutter, it'll record which focus points locked but it has no way to know if you then moved the camera...

Good point on recomposing!.. But no I don't generally do that. If I do, I let go and press the shutter again. Even if I don't recompose and wait for more than a few seconds, I let go and half-press the shutter again to update the metering. It is just my habbit.
And say that I did recompose w/o letting go off the shutter and captured the image, this still would not explain why there are two unrelated point of focus.

I will try and post a picture about this later. I am not sure if I should do it here or start another post about this.
I should have actually started another thread about this because this is a whole different subject to discuss on...
 
And say that I did recompose w/o letting go off the shutter and captured the image, this still would not explain why there are two unrelated point of focus.

Well, if both of those points were on the same plane when it locked, and then you moved the camera such that one of them is now on the background, and the other is still on the subject, it would explain it.
 
And say that I did recompose w/o letting go off the shutter and captured the image, this still would not explain why there are two unrelated point of focus.

Well, if both of those points were on the same plane when it locked, and then you moved the camera such that one of them is now on the background, and the other is still on the subject, it would explain it.

Himmm... You are right!.. I didn't think that way. If the both points were on the same plane first and then one might get off the same plane when the camera moves.

I will pay attention to this next time but I know myself. I don't recompose...
All my lenses are AF lenses (they are in my signauture). I guess this is due to equipments are not being perfect. Or maybe my gear is not up to it...
 
How far off (in the 2d plane of the image), is the background point from the other point? From what I've read the actual autofocus point is larger than the box that illustrates it. Perhaps part of it was over the subject?
 
I know in the canon system, the autofocus sensors and software are in the camera body. Different lenses focus better or worse depending on which body they're attached to. It seems however, that all you have to do is trick the body into thinking a lens has the appropriate electronics and the auto-focus confirm will work for manual lenses. I have an M42 lens with no onboard electronics, and the adapter that I use to attach it to my Canon has a little circuit that simply tells the body that a lens is attached, it doesn't actually communicate with the lens, but that enables af confirm.

Thanks for that info, I'll have to look into it.
 
Tyler, you were right, actually. I was doing some tests with the 105mm AI and low-and-behold, I noticed the focus light come on. I was like "what the heck!?". I tried before and no light came on, so I was confused. What I neglected to realize, though, was that that light comes on only when the shutter button is pressed halfway. My guess is that I didn't have the button pressed when I check last time. Thanks for the help.
 
Tyler, you were right, actually. I was doing some tests with the 105mm AI and low-and-behold, I noticed the focus light come on. I was like "what the heck!?". I tried before and no light came on, so I was confused. What I neglected to realize, though, was that that light comes on only when the shutter button is pressed halfway. My guess is that I didn't have the button pressed when I check last time. Thanks for the help.

No problem, I'm glad you got it all sorted out. Pretty nice to have some focus-faith in your MF lenses, huh?

Another thing you may want to consider (if Nikon has a setting for it) is back button focusing. I use the AEL button on my 5D to engage the AF drive. However, when I hold the button down while the lens is in MF, the focus confirm light will still turn on when the image is in focus. I find it's easier than depressing the shutter half way. The shutter on the 5D is also a soft touch shutter, so it trips very easily. That also may be a deciding factor.
 

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