I have a pair of 800E cameras and they are both doing the same thing. I have my focus switch set to "AF". I am using "AF-S" and "S" (not "Auto"). I mainly keep my focus point in the center. So, here is my problem: too many times I will be focusing on something, the camera is in focus and then all of a sudden as I'm getting ready to depress the shutter button all the way, the focus point starts jumping around all over the place! I keep going in to "custom function" to try to figure out if I have something set wrong but can't figure out what. Any help will be greatly appreciated.
My guess is that you are bumping the multi-selector with you cheek. Try locking the multi-selecto by rotating the collar so that the dot is next to the L.
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I agree, I shoot with my left eye with glasses and have had my noise press the multi-selector and changed the AF point... I would try locking it and see if that helps... If not then double check that your not in AF-c mode.... That's all I can come with...
I have noticed that when my 800E is in AF-C 3D mode the sensor moves around even though I am not moving (in tripod)and the subject is still. The rest of the AF settings don't do this.
Yes it is supposed to move around with movement to track the subject. but it should stay put if there is no movement. All I can think is that I must be moving the camera enough to alter the focus position.
Save your current settings on a memory card and do a factory reset, if the camera behavies normal after that, then you'll know that you messed something up in the settings. You can then restore your settings and see if you can find the "mistake".
Setup menu -> Save/load settings -> save settings.
I agree with Chris. Try to lock the focus adjustment using the collar lock switch. My nose hits it without my even realizing it. If it still moves at least you will be sure that is not the reason and if after you lock it, it stops moving then you will have found the problem.