Hi All - I'm having an issue with AF-C mode. Here's the rundown....
- Body: Nikon Z9 (x2)
- Firmware: 5.00
- Subject Detection: Off or On (either way the issue occurs)
- AF-Area Modes Tested: Auto Area, Dynamic Area Medium, and Wide Area AF C1 that I set to a small 1x1 square similar to Single Point AF.
- Lenses Tested (both set to allow 'Full' focus range):
a. AF-S Nikkor 400mm f/2.8G ED VR with FTZ-II adapter
b. Nikkor Z 400mm f/4.5 VR S
- Issue: When testing AF acquisition & tracking speed (e.g. continuously pressing the AF-ON button and moving the lens about to different distances), both bodies & both lenses do a great job switching from close to slightly farther away and everything in-between. However, when making a dramatic shift in focusing distance (e.g. pitcher mound to scoreboard & vice versa), the AF system gives up. The AF point or area flashes and turns red to indicate that focus wasn't acquired, and the lens doesn't hunt at all in an attempt to find a subject. The only way around it seems to be releasing the AF-ON button, positioning the lens to the new focal plane that's a lot farther or closer, and then pressing AF-ON again. Then the lens makes the big shift and AF-C mode works fine again.
- Notes: The issue occurs with both lenses (older AF-S model and newest Z model) and on both Z9 bodies. I'll admit the 400mm f/4.5 Z is a bit better in that it sometimes makes the switch from close to far in AF-C, but usually only once or twice before it fails. The older AF-S 400mm f/2.8 fails every time.
Is this a well-known issue, even with Firmware ver. 5.0?
I have noticed a similar issue. I dip the camera briefly, press the AF on button, release and refocus at the new distance. I have also read of others doing the same, but I don't know if there is a solution currently.
I have not had an issues with this much before FW4.10 with Bird Subject Detection (SD) but with Bird SD it has been really nonexistent when using Bird with Auto Area AF mode. Now I shoot wildlife 100% and of that 70-80% birds and birds in flight. With this I have no issues, even when the subject is close or far and really out of focus or defocused.
I would have Auto Area AF mode handy on a button if you are not using it just as a tap to see if it gets you close and then use your normal AF mode (you don't mention which AF mode you are using). If you are trying to initially acquire AF and SD with 3D that is likely one of the main culprits.
One thing to try is using a Wide AF mode or Auto as your default AF mode. Before FW3.0, the 3D AF mode would initiate off the center of the frame and if you missed and it was on the background or foreground it would AF hunt. With FW 3.0 and newer, 3D will initiate off the passive while AF box that you see with the Wide AF modes and Auto Area AF modes. This means when not pressing any buttons you will see a white box start to follow your subject and you can press 3D when you see the white box and it acquires and tracks from there, not the center of the frame. The white box also gives you the option to move the white AF box to the subject you want the camera to track.
But hitting the button you have Auto Area AF mode mapped to should get you in the area to then use 3D or whatever AF mode you want to try using.
I have Area AF on shutter and single point on AF-ON. It's rare that Area lets me down, but if focus racks hard and gets stuck, a quick tap of AF-ON rights it and I can resume using the shutter button immediately after the focal plane is back. I wouldn't call it a bug or problem, just part of knowing how to use the AF.
Thinking it over one workaround might be to use the Save and Recall focus position feature, which you can assign to a custom control. You can set it at the start of your shooting session to a focus distance that will work for that situation. You can set multiple positions, provided you have a custom control available to assign to it - that way you can have both the near and far distances covered to alternate to when the focus gets stuck at one distance.
If I need to go close ish focus to infinity, lens need to be in focus first. If I have something in focus at 7 meters and need to go to 75 meters- it’s instant.
If I haven’t acquired focus at 7m and want to move to 75- nope- I find focus first on a closer object,than it’s immediate.
It’s the only bug I have e found and I just deal with it- hasn’t been an issue for me but could be for others-
It's not a bug as such but a characteristic of mirrorless cameras when the subject is outside of the range of phase-detection to determine the focus distance error, it doesn't do anything. The alternative would be an exhaustive search of all focus distances and hope it catches something to focus on, might work, but would be super annoying. Use manual focus to set the subject approximately into focus and then continue with autofocus.
I don't think this problem has much to do with your settings but more a limitation of the auto focus system. Practice quick manual focus to get the subject closer before using auto focus.
I see this same behavior with super-telephotos (800E and 600E) while doing bird photography (bird subject detection AF enabled).
I end up just having to manual focus to get it closer before I can let the AF take over again.
I haven’t messed with different modes and settings too much to try and work around it.
To a degree this is just a normal part of shooting at long focal lengths and quickly adjusting the manual focus to get closer to the subject is a standard practice/skill for shooting at longer focal lengths. This is one of the reason that higher end lenses have buttons for immediately returning the focus position to some preset distance.
One thing that might be worth adding is that you have two very nice lenses there with very snappy autofocus and I've personally found that this sort of thing tends to happen more with the higher end, faster AF lenses than the less expensive stuff. It's almost like the AF in these lenses is so snappy and so "confident" that it zooms around to where the camera wants it to go and so that in some situations where the target is closer than the current position of the AF it almost seems to zoom away from where it needs to be quickly enough that the AF gets lost. On the flip side, it means that when the target is more "visible" to the AF it nails it a lot faster and more steadily.
In other words, I think pre-focusing can probably be thought of as one of the necessary skills/experience that comes with using the higher end equipment.
As others have said, this tends to be a more common characteristic amongst mirrorless cameras. Often, if the lens is focused in front of the object, it will have an easier time finding something further out than if it's focused further out and the subject is much closer in. Many use the recall focus location function just to set it something relatively close to recover when this happens
