Focus Point Questions: AF-C Mode + Image Playback (D500)

Started 9 months ago | Discussions thread
CubeAce Senior Member • Posts: 1,279
Re: Focus Point Questions: AF-C Mode + Image Playback (D500)
3

Kenny08 wrote:

Ok, new Nikon newbie so be gentle! Just trying to get things straight being from a Canon world.

Just a few questions:

Assume the scenario: AF-C mode using Dynamic Area Mode (D153 setting), and I have initial focus point (red square) on an eye of a Hawk.

I pan the camera to keep up with the hawk while keeping the object within the D153 perimeter markings of the viewfinder - the assumption here is that the focus point will move and attempt to keep on the eye of the hawk.

Questions:

1. Am I suppose to see the red focus square move along while I'm panning? In my case, it does not as it stays on one spot (My assumption is is that the focus point is moving but is not visible even though it continues to show the initial set focus point.

2. During Image Playback, the focus point also remains static on the same spot/area that was initially set. In this case, the first frame was on the eye of the hawk. Subsequent image frames would have the red focus square remain at the same location, and since I"m panning the camera, the eye of the Hawk of course is no longer at the same spot when the initial focus point was selected. This observation is normal?? I was thinking that the Focus Point would be displayed to reflect the dynamicity of the changing focus point in AF-C mode.

Thanks

First of all I don't think most people will think getting used to the Nikon focusing system is easy so if you get any demoralising replies, don't take any notice.

Second, there will be differences of opinion based on individual success with various settings and peoples individual ability to track subjects like bif accurately.

Finally, congratulations for reading the manual because I think anyone reading the manual would have come to the same conclusions of use of settings you have tried for this type of shooting.

For solutions.

Some things to my mind haven't changed with the Nikon focusing system and in the past I've found some things not to work as well as others based on my own experience so I'm sure others will disagree with what I'm about to write.

First up. The more focus assist points you use, the slower the whole system becomes as the amount of information coming into the processors slows down the whole focus system. So use as few as you can get away with. Only increase the amount of focus points when it gives you a better result than you can manage with accurate panning.

Second, try keeping the focus tracking with lock on and blocked shot AF response central until you have time to try out various fine tuning of that system as the factory settings do quite well in most situations. If you haven't touched that setting ignore this bit.

If you are using back button focus and continuous bursts decouple the shutter button release (a8 AF activation in the custom menu) and make sure setting a1 is set to Release.

This will ensure the focus doesn't 'jump' slightly as the shutter button travels fully down to release the shutter. Again, if you aren't using the back button to focus, leave those settings on your normal use settings.

Make sure face detection is turned off. If it is on in matrix metering mode and you use matrix metering mode turn it off there. There are a few things that slow down the focusing system and write speed to camera such as having high ISO noise reduction on so turn those off as well. All these alterations can be stored in a custom settings bank when you are finished so you can move away from them later if you wish.

If you are shooting with a VR lens and can keep the shutter speed above the focal length by a factor of two or more, turn VR off. If you find it much harder to pan accurately then leave it on but slightly better results can be had when it is off and you can pan accurately.

Each time you increase the amount of focus assist points you slow down the AF slightly as I said earlier. So in theory a single AF point should be faster to react than using 25 which in turn should be more accurate than 72 which in turn would be faster than using 153. This is the point where people will argue I think and a lot will depend on how well an individual can track a subject accurately. This is where people will find one mode better than another and experience / ability, will give different results.

I personally find that for hawks, eagles, peregrines, and similar birds that I can track with reasonable confidence using 25 points dynamic area AF. That is the best working compromise for me. Combined with a relatively slow focus tracking with lock on and blocked shot AF response setting, helps stop the focus from jumping to another point too soon despite whatever Nikon has printed to make me think otherwise. If you can get the center focus point on the birds head and reasonably fill the frame with the subject, (around one fifth to one quarter of a frame) then the focus system will not wander much from that even if you wander off the bird for a very short period.

The focusing group was initially on the birds head but has now gone towards the back of the tail during tracking and yet the main focus is still clearly on the birds head.

This is earlier in the sequence and you can see I've not been that accurate due to the speed of the bird and trying to keep it in the same focus area.

Personally I have found these settings to be the best for my personal abilities and the focal lengths I have available.

There is a possibility that lenses with different maximum open apertures may also make a difference to performance. I have only used a 70-200mm f2.8 lens for these types of pictures, sometimes with an additional 1.4TC bringing the aperture up to f4 and have found the hit rate of usable images for me to be reasonably high.

I am sure there are more competent birders out there that can do much better than myself and others using different lenses and finding other settings working better than I've suggested.

All I can do is relay my own personal experience and hope it may be of some benefit.

[ Edit]

I've just realised the pictures I've added have no exif detail as they are screen grabs showing the selected focus points from Capture NX-D.

Roughly they are.

14 bit RAW uncompressed.

AFC: Dynamic Area AF 25 point. using back button focus, shutter button decoupled.

f2.8 1/2000s 0EV Exp comp. Center weighted metering.  ISO 200. VR off. Picture control base Neutral with sharpening at 6, clarity -2, contrast +1

Burst mode at 10fps.

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