D7100 Inconsistent Focus Tracking Errors

[Paganman2]

Watch the video. This may help you with your problem:

How to use Nikon's AF-ON and back button autofocus | Nikon Rumors

Hi thanks for that, i am confused how it would work? as its not a general focus problem i am experiencing, its seems to be a specific focus problem relating to accurate focus detection of aircraft flying towards the camera, all other focus regimes are spot on and fully accurate - from focus tracking of aircraft flying along the horizon, BIF movement in any direction is also spot on, and static shots are perfect.
Its a weird focus problem i am experiencing but there must be an answer to it, i just want the reassurance that if i put my focus box on the subject in the right focus mode, it will deliver sharp focus.

P.

 

[J-see]

It's hard to imagine but could it have something to do with the fact that the cam is determining correct focus upon an object moving towards it at high velocity? The cam is in such a situation always determining focus upon a position no longer required. But like I said, it's hard to imagine there would be such a difference between the cam's calculation and adjustment and the aircrafts velocity, this could even be a problem.

But with a fast aircraft and a very thin DoF, it could be a possibility.

 

[Horoscope Fish]

Have you tried using Auto-focus Continuous with 3D Tracking enabled?

There are no guarantees when it comes to Auto-focus but the 3D Tracking option might solve the problem.

....

 

[Paganman2]

Have you tried using Auto-focus Continuous with 3D Tracking enabled?

There are no guarantees when it comes to Auto-focus but the 3D Tracking option might solve the problem.

....

I've tried 3d but it just jumps around the screen and if things like clouds or other objects are in the scene it gets confused and in the time it takes - the plane has gone.

The best i have seen so far is with AF-A as this seems to stop the AF non lock, and the focus confirmation lights telling me its locked on something, but i didn't think AF-A was supposed to be for movement/tracking?

P.

 

[Don Kuykendall_RIP]

Have you tried Back button Focus? I found it a lot better for my bird in flight shots.

 

[weebee]

How many point focusing are you using. When I'm doing this I drop it down to 9 point. At times the 51 point system will work against you with these types of shots.

 

[Paganman2]

Have you tried Back button Focus? I found it a lot better for my bird in flight shots.

I dont understand how back button focus would help as all it is doing is the same thing as the shutter button but from the back,
and the strange thing is - there is no difference in focus or any other settings or conditions between those two pictures i took of the exact same plane shot at one frame at a time but about 5 seconds apart.

P.

 

[Don Kuykendall_RIP]

I dont understand how back button focus would help as all it is doing is the same thing as the shutter button but from the back,
and the strange thing is - there is no difference in focus or any other settings or conditions between those two pictures i took of the exact same plane shot at one frame at a time but about 5 seconds apart.

P.

With Back Button Focus you can click on the plane and lock on and then release and shoot when ready. Also it works as spot meter when you release and if you hold it acts as continuous. It really does not act the same at all.

 

[Paganman2]

How many point focusing are you using. When I'm doing this I drop it down to 9 point. At times the 51 point system will work against you with these types of shots.

One or nine point dynamic, never more than that as i understand the extra focus points would confuse things, this is why - in answer to a poster above, i wont use 3d too many distractions.

P.

 

[Eyelight]

@Paganman2 Can you upload an uncropped shot?

 

[Paganman2]

@Paganman2 Can you upload an uncropped shot?

Of the same two planes i posted further back?

P.

 

[Eyelight]

Of the same two planes i posted further back?

P.

Whatever is easy. I'm curious on how the plane fits the viewfinder and a picture would work better than my imagination. (Though, I do have a technicolor imagination.)

 

[Paganman2]

Whatever is easy. I'm curious on how the plane fits the viewfinder and a picture would work better than my imagination. (Though, I do have a technicolor imagination.)

OK i do it now.

P.

 

[Paganman2]

Here are the originals completely un worked just re sized, its hard to see the difference at this stage, that is why i always crop my pictures - not by 100% but normally in the range of about 50%.

P.

 

[J-see]

I'm not shooting planes but I know that when I shoot birds in flight and they're too small while I use too many focus points, there are times the focus tends to lock in mid-air. There's nothing to see in my shot but for some reason, it decided to focus there. If you use focus lock at the same time, it'll remain there x amount of time.

If you load the shots in Capture NX-D or ViewNX-2 and check the focus point, did it lock on the plane?

 

[Paganman2]

I'm not shooting planes but I know that when I shoot birds in flight and they're too small while I use too many focus points, there are times the focus tends to lock in mid-air. There's nothing to see in my shot but for some reason, it decided to focus there. If you use focus lock at the same time, it'll remain there x amount of time.

If you load the shots in Capture NX-D or ViewNX-2 and check the focus point, did it lock on the plane?

Yep i checked that in camera before saving to computer, the center focus point in both pictures is dead center in the middle of the planes between the wings and fuselage, one focus point covered about 80% of the plane so i would say the focus point was where it should be.

P.

 

[J-see]

Yep i checked that in camera before saving to computer, the center focus point in both pictures is dead center in the middle of the planes between the wings and fuselage, one focus point covered about 80% of the plane so i would say the focus point was where it should be.

P.

Focus tracking with lock on was the correct term, focus lock is the switch.

Do you always have this problem or is it random? Like the one day all is fine, the other most are out of focus?

 

[Paganman2]

Focus tracking with lock on was the correct term, focus lock is the switch.

Do you always have this problem or is it random? Like the one day all is fine, the other most are out of focus?

It is random during the same days shooting where it would typically focus inconsistent, its the same all the time on one such day where i spent several hours from my garden taking pics and logging planes, out of about 180 pictures all with the same lens/camera and the same settings weather etc and all the planes being the same directions and same kind of hights, only about 100 where in focus, and i mean the kind of focus that puts a smile on ya face, the rest were just out of focus at different degrees but similar to the cropped one i have shown, when a plane came over even lower the focus was even harder to nail, and so far i have not been able to get a sharp focused closer plane yet.

P.

 

[Eyelight]

I think you are experiencing some motion blur, perhaps a combination of subject and camera movement. I'm leaning that way because, 1) the camera does well on all but a certain motion of shot, 2) the OOF image looks more like motion blur than a soft focus especially the leading edge of the engines and 3) the closer the plane, the faster it is moving relative to the camera and you mentioned no good shots in the close range.

I'm just guessing that maybe the shots you are having trouble with are ones that are harder to maintain a smooth pan.

Now, you know more about what you are doing, so does any of this make sense????

 

[Paganman2]

I think you are experiencing some motion blur, perhaps a combination of subject and camera movement. I'm leaning that way because, 1) the camera does well on all but a certain motion of shot, 2) the OOF image looks more like motion blur than a soft focus especially the leading edge of the engines and 3) the closer the plane, the faster it is moving relative to the camera and you mentioned no good shots in the close range.

I'm just guessing that maybe the shots you are having trouble with are ones that are harder to maintain a smooth pan.

Now, you know more about what you are doing, so does any of this make sense????

Thank you for having a look at this for me i appreciate it and feel welcomed by all on this site, i have been a long-ish time lurker and read all the DX forums but then decided to join and now i am glad i have, anyway -
Do you think it would help to up the shutter speed to 1250-1500 esp as i crop a fair bit? and is it logical that the reason i did not have these troubles with either my D200 or D90 with my 55-300ED VR was down to the resolution difference of 8/12 compared to 24 or 16 if i use the crop mode in the D7100>
I had read that the higher resolution of these high power sensors puts a lot of stress on the lens and the users ability to get the best out of them, and that our technique needs to improve compared to the lower older sensors like my D90/D200.
Does any of that make sense?
Also sometimes i used to get better focus with grab shots where i fired as soon as a plane was in the frame roughly where i wanted it without me following or panning?

P.