Focusing Points Question D850

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Howard5252

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I'm used to shooting BIF using Single Point focus; If I use GrP or d25 is it possible that one focus point will be on the bird and another point on something behind the bird or will panning eliminate that possibility? With GrP (specifically), is there any focusing going on in the middle of the 4 focus points ... it's a bit disorienting because that's where I'm used to keeping the bird - or at least trying to.
 
D25 will try to use the selected point and only go off if it cannot reacquire focus in the selected time from the in camera settings selected by the user. Then it will try other points. Group AF also uses the selected point in the centre Of the group, and only uses the other points if the selected one looses focus. It won’t typically focus behind because group AF uses the closest subject to the camera as a priority. The downside is that means if something else is closer to the camera than the intended subject it may go off. The older system (in your example D25) for uses a different system, and could very well miss and focus behind If the colour of the subject and something else are similar. It’s always a chance, but overall they work as intended.
 
Actually Grp AF on the D850 uses 13 AF points, they're just represented by the 4 shown. Grp is a close-focus priority mode and will generally (although, not always), focus on the part of the subject that's under the AF area closest to the camera. It can use any point in the array to do so. It also tends to lock on faster and more reliably than other modes, since each AF point carries the same "weight".

The Dynamic modes have a primary AF point. Ideally, you use that primary AF point and if you stay on target, it'll continue to use that point. However, if your primary AF point slips off target, one of the other points in the array will attempt to take over. However, on the D850 (and D5/6, D500), the camera will only wait a very short time for you to get back on target before it tries to focus using the primary AF point again (this delay is set with custom setting A3). So, it's like single point AF with a safety net.
 
Actually Grp AF on the D850 uses 13 AF points, they're just represented by the 4 shown. Grp is a close-focus priority mode and will generally (although, not always), focus on the part of the subject that's under the AF area closest to the camera. It can use any point in the array to do so. It also tends to lock on faster and more reliably than other modes, since each AF point carries the same "weight".

The Dynamic modes have a primary AF point. Ideally, you use that primary AF point and if you stay on target, it'll continue to use that point. However, if your primary AF point slips off target, one of the other points in the array will attempt to take over. However, on the D850 (and D5/6, D500), the camera will only wait a very short time for you to get back on target before it tries to focus using the primary AF point again (this delay is set with custom setting A3). So, it's like single point AF with a safety net.
Thank you; I set A3 to 2 & Erratic. Will be using d9. I'll give that a try for a few weeks and see if my "Keep" rate goes up.
 
Thank you; I set A3 to 2 & Erratic. Will be using d9. I'll give that a try for a few weeks and see if my "Keep" rate goes up.
Keep in mind the subject motion portion of that setting isn't what you may think it is. When Nikon talks about "erratic" vs "steady" they are taking about if a subject is prone to sudden stops and starts. If so, erratic is correct (like a bird taking off / landing). Otherwise, set in the middle or to steady (mine is usually in the middle). Also, don't be afraid to play with it a bit. If the camera seems to let go of the subject too easily, set the delay value higher, if it's too sticky, set it lower.
 
Keep in mind the subject motion portion of that setting isn't what you may think it is. When Nikon talks about "erratic" vs "steady" they are taking about if a subject is prone to sudden stops and starts. If so, erratic is correct (like a bird taking off / landing). Otherwise, set in the middle or to steady (mine is usually in the middle). Also, don't be afraid to play with it a bit. If the camera seems to let go of the subject too easily, set the delay value higher, if it's too sticky, set it lower.
Will do; set it back to where it was. I've seen the video where you talk about a tree getting in the way (perhaps momentarily) and the camera losing focus. I just didn't apply it to BIF. The manual says diddly about Subject Motion (Page 260). Thanks again for all that you do.
 
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