D7100 back button focus confusion

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Englischdude

Senior Member
Hi all,

I have decided to commit to trying the BBF feature of the D7100 for a couple of weeks to see how it works out. I have a kids birthday tomorrow and my 3 yr old daughter will be going into the skischool next week, good opportunities to practice. I am a bit confused about the settings. So far I have done as follows:

Enabled AE-L/AF-L butto to AF On (effectively relocating focusing from the shutter release button to the AE/AF L button. Works no problem.


Under the custom menu Autofocus settings I have set:
a1 to AF-C release priority
a2 to AF-S focus priority

According o the myriad of tutorials I have found on the web this should be it, but what should I be setting the focus mode to (using the little button left of the lens and selector wheel)? AFS AFC AFA? in AFC I have tried setting to d9 d21 and d51, however the focus point has to be always individually selected with the arrow buttons. I see no difference whatsoever when changing these settings. is that correct?
For example, if I set to AFC D9, in the viewfinder the focal point is a single point which I have to manually move to any one of the available 51 points!

Im confused! If anyone else has their D7100 set up for BBF I would appreciate knowing you settings.

thanks in advance for your help!
 
Horoscope Fish

Horoscope Fish

Senior Member
Englischdude said:
Hi all,

I have decided to commit to trying the BBF feature of the D7100 for a couple of weeks to see how it works out. I have a kids birthday tomorrow and my 3 yr old daughter will be going into the skischool next week, good opportunities to practice. I am a bit confused about the settings. So far I have done as follows:

Enabled AE-L/AF-L butto to AF On (effectively relocating focusing from the shutter release button to the AE/AF L button. Works no problem.


Under the custom menu Autofocus settings I have set:
a1 to AF-C release priority
a2 to AF-S focus priority

According o the myriad of tutorials I have found on the web this should be it, but what should I be setting the focus mode to (using the little button left of the lens and selector wheel)? AFS AFC AFA? in AFC I have tried setting to d9 d21 and d51, however the focus point has to be always individually selected with the arrow buttons. I see no difference whatsoever when changing these settings. is that correct?
For example, if I set to AFC D9, in the viewfinder the focal point is a single point which I have to manually move to any one of the available 51 points!

Im confused! If anyone else has their D7100 set up for BBF I would appreciate knowing you settings.

thanks in advance for your help!
Click to expand...
Okay this is easy and I think you're probably just over thinking things... First of all, you have BBF set up correctly. So, we need to separate the HOW you focus from the WHAT you focus on. You initiate focus using the back-button, so that's taken care of; you're good on this point.

WHAT you focus on is determined by the Auto-focus mode and the Auto-focus Area-mode. You really want/need to use AF-Continuos as your AF-mode with BBF and I use Dynamic 9-Point for the AF Area mode; I think it's one of the most flexible of the available options. I think where you're getting confused is when you look through the viewfinder, you see one focus point selected, even if you're using, say D9 as I am. But... Press the AF/MF button on the camera body and you'll see all nine points illuminate in the viewfinder. As you move the center-point around in the VF using the four-way button, you can press and hold that AF/MF button and you'll see the whole 9-point array move around the frame.

.....
 
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Blade Canyon

Senior Member
AF-C is one of the whole points of using BBF. The auto-focus keeps working while you hold the back button, but you can let off once you have locked focus and recompose. I love to shoot people, so I use a single focus point, focusing on the eye closest to me, then let off the back button and recompose.

But, when you have a moving target, such as the ski school or birthday party, you can keep holding the back button while shooting, and you can increase your focus points to whatever choice suits you best for a moving target.
 
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Englischdude

Senior Member
Horoscope Fish said:
WHAT you focus on is determined by the Auto-focus mode and the Auto-focus Area-mode. You really want/need to use AF-Continuos as your AF-mode with BBF and I use Dynamic 9-Point for the AF Area mode; I think it's one of the most flexible of the available options. I think where you're getting confused is when you look through the viewfinder, you see one focus point selected, even if you're using, say D9 as I am. But... Press the AF/MF button on the camera body and you'll see all nine points illuminate in the viewfinder. As you move the center-point around in the VF using the four-way button, you can press and hold that AF/MF button and you'll see the whole 9-point array move around the frame.

.....
Click to expand...

got it, holding down the AF/MF button I see all 9 points illuminated and I can move them around to my hearts content, great! however when I release the AF/MF button I go back to single pont selection and I can select whichever point I want out of 51 available, so what sense does selecting D9 make?
 
Horoscope Fish

Horoscope Fish

Senior Member
Englischdude said:
got it, holding down the AF/MF button I see all 9 points illuminated and I can move them around to my hearts content, great! however when I release the AF/MF button I go back to single pont selection and I can select whichever point I want out of 51 available, so what sense does selecting D9 make?
Click to expand...
Yes, with D9 activated you only see the center point of the array in the VF, but the mode *uses* all nine points of the array all the time; you just don't see it in the VF.

If you're asking why one would choose to use D9 vs some other AF-Area mode well that's a personal choice, of course. I just happen to find it suits my needs. It will handle stationary objects like Single Point but has the ability to track a slightly, or slowly, moving target. This works for me for when the wind, for example, is blowing my subject around a little or I need to slowly pan a moving target. If my target gets faster, or more erratic, then I switch to D21 but D9 covers 95% of shots probably.
....
 
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E

Englischdude

Senior Member
Horoscope Fish said:
Yes, with D9 activated you only see the center point of the array in the VF, but the mode *uses* all nine points of the array all the time; you just don't see it in the VF.

If you're asking why one would choose to use D9 vs some other AF-Area mode well that's a personal choice, of course. I just happen to find it suits my needs. It will handle stationary objects like Single Point but has the ability to track a slightly, or slowly, moving target. This works for me for when the wind, for example, is blowing my subject around a little or I need to slowly pan a moving target. If my target gets faster, or more erratic, then I switch to D21 but D9 covers 95% of shots probably.
....
Click to expand...

many thanks for the explanation, what was confusing me was the selecting 9 21 or 51 points AF, but only seeing one point through the VF.
Ill experiment during the coming weeks and see how I get on with this new setup.
 
Horoscope Fish

Horoscope Fish

Senior Member
Englischdude said:
many thanks for the explanation, what was confusing me was the selecting 9 21 or 51 points AF, but only seeing one point through the VF.
Ill experiment during the coming weeks and see how I get on with this new setup.
Click to expand...
Understandable... I don't know why the whole array doesn't illuminate in the VF when active, I wish it would too if for no other reason than it would remind me what mode I'm currently in, but... It don't. :(

....
 
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