When do you use Group AF?

Joined
May 3, 2009
Messages
209
Location
North Carolina
Hello all,

This is primarily a curiosity question.

I know that some of you have spoken glowingly about Group AF. I have been using D25 (and before that D21) almost exclusively and generally for sports.

But I’m wondering about what you feel are the advantages of Group AF and when you think are the best times to use it and for what subjects you prefer it.

Spring is (I hope) somewhere in the near future, and before I get back outside, I thought it might be a good time to learn something new.

Thanks for your insights.

Sincerely,

Andy
 
Joined
Mar 4, 2005
Messages
15,280
Location
Los Angeles, USA
I've been using group AF more often now, though I use it differently depending on the lens. On my telephoto lenses, I use it shooting with AF-C with focus lock-on set to 'short' so it's continuously adjusting. On wide lenses, I use AF-S using the old school focus and recompose method. Since DOF is deeper at the wider FLs, even slight movement will still be in focus. Group AF works in either scenario using AF-C or AF-S. If I need to shoot more detailed images such as close-up and/or portraits where I need to make sure the eyes are in focus, I'll switch to single point AF to make sure it focuses on a specific area.

Prior to that I only used D9 and I alway set my camera to 11 AF points (focus skipping on the Z bodies), versus using the full AF coverage because it slows me down having to maneuver the d-pad/joystick through the full focus area.
 
Joined
Jan 2, 2009
Messages
5,045
Location
Alaska
BIF. As Bill said particularly when the BG is busy or low contrast with the subject. D25 etc can get confused in those situations and lock on something in the BG. The advantage about Group AF is that it doesn't think for itself. It simply locks onto the thing that is closest to the camera under one of the five focus points in the group. So it is more predictable. It does take some care if you're focusing on a bird that flies down close to the water/ground or if shooting a low angle at a small bird/critter on the ground or surface of the water. In those situations if you have the subject centered up and the bottom points in the group fall on the surface/ground that is what they will lock on to.
 
Joined
Jul 8, 2019
Messages
425
Location
SF Bay Area, California, USA
It DEPENDS, on the subject, lens and specific shooting scenario.
Photographers judgement, based on experience.

I only use zone focus for SINGLE subjects; like tennis singles, or baseball outfield. Where nothing else will be in the focus area, to draw the camera away from my subject.

In my experience, any situation where there are more than one person/subject/object in the focus area/zone, there is a strong probability that the WRONG subject will be selected by the camera, to focus on. In fact in some cases, there is a 99% probably that the wrong subject will be selected. Then I use Single Point D9, so I select the subject, not the camera.

Example1, volleyball. When shooting the spiker on the far side of the court, there will be two players between the spiker and me. The camera will focus on the closest of the two players, and NOT the spiker.

Example2, football. The QB is running through a break in the line, there are the players on both sides of the break, who are between the QB and me. The camera will focus on these players, NOT the QB.

Example3, tennis. Shooting over the net, the net is between the player and me. The camera will focus on the net, NOT the player.

Example4, basketball. Some of my shots are threaded between two other players. Zone AF would focus on the closer of the two other players, NOT my player who on the far side of those players.

So, in general, for the sports that I shoot, and how I shoot, I use Single Point D9.
I rarely use group AF, because of the problems with other players in the AF area.
 
Joined
Oct 4, 2006
Messages
2,158
Location
Chicago, IL
I find it almost flawless for photographing figure skating singles or pairs. However, when there are more 2 skaters on the ice.... I move to 51 pt. so as not to latch on to the wrong skater.
 
Joined
Jan 2, 2009
Messages
5,045
Location
Alaska
...So, in general, for the sports that I shoot, and how I shoot, I use Single Point D9.
I rarely use group AF, because of the problems with other players in the AF area.
I'm confused. Some of us must be using different terminology. Single Point D9? Isn't D9 by definition mean it is using 9 focus points? D stands for Dynamic and the number is the number of focus points involved.

My understanding is that the problem of other players in the focus area is exactly what is intended to be eliminated by Group AF. Group AF is the smallest focus are and least number of focus points(5) other than Single point AF.

Are we all talking about the same generation camera? i.e. D5/850/500 series?
 
Joined
Feb 1, 2005
Messages
1,781
Location
Tennessee
In the dynamic focus setting (9, 25, 72, 153) you have the center focus point active when focus is initiated. Once locked, if the target moves away from that center point the surrounding points will track the focus. And when I say center, it is the center of the group of 9, or 25... you can move that around. But again it is just one focus point to first grab focus and then the other will pick up if the target moves off that point.

Group focus uses a group of points to grab focus. So instead of try to land that single center point in your dynamic setting of 25 at the start of focus, with group you are using multiple focus dots to create something of a larger area for lock on.

So in baseball if you are trying to swing your camera to the outfield and pick up a running centerfielder, it is a lot easier to use group and have a bigger sight to put on him, then trying to put that single AF dot on him to first get focus.

Just remember that in dynamic say D25, not all 25 points are trying to gain the initial focus, just one is doing that, and then those other points will hand off if the target moves out of the center in that 25.
 
Joined
Jul 8, 2019
Messages
425
Location
SF Bay Area, California, USA
I'm confused. Some of us must be using different terminology. Single Point D9? Isn't D9 by definition mean it is using 9 focus points? D stands for Dynamic and the number is the number of focus points involved.

My understanding is that the problem of other players in the focus area is exactly what is intended to be eliminated by Group AF. Group AF is the smallest focus are and least number of focus points(5) other than Single point AF.

Are we all talking about the same generation camera? i.e. D5/850/500 series?
In reverse order

Apparently not, and the OP has not stated which camera he has.
So I answered more generically.

I am bouncing between several cameras, so I sometimes do get things confused, between cameras.

My D7200 has the following C modes: S, D9, D21, D51, 3D, Auto
As Todd said, D modes are center start, not all points immediately active (as Canon is).​
My EM1-mk2 has: S-large, S-small, 3x3 cross, 3x3 square, 5x5 square
It also has center start and center priority (which I think is similar to the Nikon D-modes).​
My EM1 has: S-large, S-small, 3x3 square, all points
The schools Canon T7i has: S, 3x3, 3x5, Auto (full frame)
Zones use "closest subject" logic to determine what to focus on inside of that "zone."​

I use the term "single point D9" because as @F15Todd said, I am aiming a single point, unlike the Canon 3x3 mode which uses ALL 9 points to find what to focus on. So with D9, I am aiming a rifle, vs Canon's 3x3 where I am aiming a shotgun.
Then if I cannot hold the subject, I let the camera use a 3x3 zone to track the subject. HOW the camera tracks the subject is a different but related subject, which I do not know the answer to.

Based on my being able to shoot a subject between two other players who are closer to me, this tell me that the D9 is indeed working as a single point AF on the subject, and not using the 3x3 area.
By the same token, when I "just miss" the subject, on a quick subject change, the camera focus on the background, not my subject.
So D9 does require precise placement of the active AF point on the subject, to start. It is not a shotgun.

I just read the D7200 manual again (when in doubt RTFM).

There was nothing in the manual, that indicated HOW, the Nikon Dynamic modes tracks the subject when it moves off the primary AF point. Is it subject color, distance, or ??? The details of D mode is a mystery to me.​
Nikon's 3D tracking uses the color of the AF points AROUND the primary AF point, to determine and track the subject. So if the background color is NOT consistent, or the subject and background are of a similar color, it may loose tracking.​
 
Joined
Jul 8, 2019
Messages
425
Location
SF Bay Area, California, USA
Forgot to add, I have used group for baseball/softball with good results. That is really the only sport I use group with.
Yup me too.
I was shooting HS baseball today, with the Olympus, and used 3x3 zone for most of the game.
The players were usually separated enough that the 3x3 zone only covered ONE player.
It was great for the pop flys, where I sometime have trouble nailing the catcher in outfield, with the LONG lens.

The Olympus 75-300 reminded me why I like the 70-200/4 so much for field sports.
The stiff/sticky zoom ring was a PitA to use for shooting baseball.
 
Joined
May 3, 2009
Messages
209
Location
North Carolina
Thank you all for your responses.

I like the analogy of rifle sight versus shotgun.

I'll admit that I've pretty much stuck with D25 and before that D21 for the bulk of my shooting, with Auto-Area thrown in occasionally.

Since baseball will be starting up soon, I may play with Group AF at some early games to see how well it works for me. (I get out in the woods to hike, but I don't photograph (moving) birds really at all.)

I've also played a little bit with 3D tracking, again mainly out of curiosity, although what I did wasn't really much of a test.

Again, thank you, although by all means don't think of this as a stopping point for this thread. Any day I learn something is a good day.
 
Joined
Feb 2, 2005
Messages
8,116
Location
Maple Bay, Duncan, BC, Canada
Real Name
Andreas Berglund
Just to expand on this a bit. I have 4 different focus modes setup on each of my D500 and D850 assigned to buttons as follows
  • AF on button: Single point, I use this on sitting birds, and on lots of other images, I point focus on what I want then recompose and shoot.
  • Joystick button: Group AF, I use this on BIF mostly
  • Top front function button: 3D tracking, I try to sue this on erratic flying birds
  • Bottom function button: 25 or 72 point use this on people when there are several of them and one is slightly closer than the othersm that way I get the first on in focus and hopefully at F8 the rest as well
I'm sure others have totally different setups
 
Links on this page may be to our affiliates. Sales through affiliate links may benefit this site.
Nikon Cafe is a fan site and not associated with Nikon Corporation.
Forum post reactions by Twemoji: https://github.com/twitter/twemoji
Copyright © 2005-2019 Amin Forums, LLC
Top Bottom