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Nikon D7000 focus tracking


thatmanbrian 9 342 3 Spain
4 Sep 2011 10:45PM
Blah!
User_Removed 16 4.3k 2 United Kingdom
5 Sep 2011 12:40PM
Surely single point focus is the way to go, that way you lock onto the bird and the lens focuses on that point.
Using 39 points offers too much choice.

I use the D7000 for my bird shots but don't have fast enough reaction times for birds in flight, mainly because I can't hand hold lenses.
thatmanbrian 9 342 3 Spain
5 Sep 2011 2:51PM
Does single-point actively track though, or does it lock onto that distance even if the bird gets closer? Just seen your portfolio aftertherain, great shots you clearly have no problem focussing! I'm planning another sanctuary visit soon to experiment further BTW.
LenShepherd 13 4.4k United Kingdom
5 Sep 2011 8:46PM

Quote:As soon as it takes off, I pan with it shooting on continuous, but the AF doesn't even manage to get the first shot in focus.Sad Hence my suspicion there is a fault? As I already mentioned, sometimes when framing a distant shot after a close one, the AF seems to refuse to refocus.

Without links to images it is difficult to comment in detail.
Birds in flight need to be a minimum size for AF to detect them and then track them. Adding to this some birds, especially if back lit, are poor AF targets.
Going from targets at the opposite end of the focus range does occasionally (but not often) prevent AF reacting because the image is so unsharp that there is total detail blur at the AF sensor.
The D7000 AF sensors cover a slightly smaller area of the viewfinder than with the D300s so I am guessing although the D7000 has fewer sensors the D7000 detection lines are not much shorter - and should work with a similar minimum size targets.
My D7000 works perfect with the 70-200 picking out individual cyclists faces in a bunch traveling at 25 mph (uphill) - my combination with good detail targets works very well.
One thing to be aware of if you use the new D7000 AF-A focus option is the AF method changes from focus priority with static subjects to shutter priority with moving targets - unless you change menu option a2 in the menus.
It is not unreasonable to presume in AF-A focus is always shutter priority - but it is not Sad See page 91 of the instruction book - particularly the explanation of AF-S focus mode.
If you do not change the menu option when the bird takes off the camera changes focus method, which could help explain why you are having difficulty getting the first picture sharp.
thatmanbrian 9 342 3 Spain
5 Sep 2011 9:56PM
Thanks for your detailed reply.

This is the first in the continuous take:
-dsc6726.jpg


-dsc6734.jpg


the other is the last - I'd lost framing a bit! Hope this helps. It's not the worse example but I deleted those! The final image seems to be focussed on the legs? am I expecting too much?

I'll follow up your suggestions anyway.
Brian
LenShepherd 13 4.4k United Kingdom
6 Sep 2011 10:53AM
Thanks for the pictures.
You have a fairly fast flying back lit dark brown bird, starting flight from a background in shadow in the first shot.
In the second shot the bird is closer to the camera at greater magnification - which requires much faster AF tracking than the first shot.
I suspect had the bird being flying into the light making it a much better AF target D7000 AF and the 70-200 would have performed much better.
I would expect even my D3s would have AF tracking accuracy difficulty with an AF target as poor as this one.
thatmanbrian 9 342 3 Spain
6 Sep 2011 11:35AM
Hmm. I thought this might be the case. I do have successes as here in the wild. He was flying quite sedately though.

nature-closeups003.jpg
LenShepherd 13 4.4k United Kingdom
7 Sep 2011 9:01AM

Quote: He was flying quite sedately though.

Apart from being a much slower flyer than a bird of prey, there is plenty of contrast detail created by the feathers that make up the wings and the neck outline.
This confirms your camera AF and lens are good with a good AF target. Your previous pictures show your AF and lens could not cope with a fast moving much poorer AF target.
Perhaps you need to spend some time learning the types of target that can sometimes defeat AF. There is guidance on this on page 93 of the D7000 instruction book or at https://nikoneurope-en.custhelp.com/app/answers/detail/a_id/4585
thatmanbrian 9 342 3 Spain
7 Sep 2011 9:13AM
OK, well thanks for all the advice folks. As Lenshepherd says, it all depends on the subject and I think my expectations are maybe too high. I'll perservere and keep trying and I'm lucky to be within driving distance of two bird sanctuaries. I also spend a lot of time on the nearby River Stour where I can see herons and Kingfishers. (Now THERE'S as fast subject!!!) The Red Arrows plane crashed right on one of my favourite pitches but I have since seen 'my' heron again, so he escaped. The pilot unfortunately didn't. The outpouring of sympathy from the locals was very touching.
Brian
User_Removed 16 4.3k 2 United Kingdom
7 Sep 2011 9:03PM
Do you remember those balls on a pole that you could hit back and forward?
Set something like that up, with a couple of 'wings' and try different settings to see which works best.
thatmanbrian 9 342 3 Spain
7 Sep 2011 9:44PM
Or I could borrow next door's moggie and catapult him into the air....
Maybe not Wink Seriously aftertherain, a good idea, if nothing else might get a nice abstract shot out of it!
LenShepherd 13 4.4k United Kingdom
8 Sep 2011 10:13PM

Quote:Or I could borrow next door's moggie and catapult him into the air....


If you did that you might identify one of the limitations of AF focus tracking Wink
Focus tracking guesses where the subject will be when the shutter opens, based on the speed and direction of movement before the shutter is opened.
If the subject is speeding up or slowing down AF guesses with less accuracy - which takes us back to your relatively poor AF results with birds for the first shot after take off.
All good moggies are able to rotate their bodies in mid air to help land on their feet - Nikon probably did not allow for mid air cat acrobatics when deigning focus tracking systems.
Outlander 11 96
11 Sep 2011 9:01PM
Have a look here, although the guide is written for d3/d3s/d300/d700 cameras a lot of the points mentioned can be used for the D7000.

Head on over to Nikon europe eu>service and support>support and downloads.What you are looking for is the guide to Professional Sports Photography
Article 26800.Its a PDF Download

The guide recommends best camera and lens settings for different types of sports photography under various shooting conditions.Grin
thatmanbrian 9 342 3 Spain
11 Sep 2011 10:01PM
OK thanks outlander - will pop over there now!
Brian
thatmanbrian 9 342 3 Spain
11 Sep 2011 10:34PM
Got it - very interesting. As it hapens, I'd been experimenting with some of the settings they recommend such as just 9 focus point and today shot some surfers - admittedly not as fast moving as vultures! But I got decent results. Trouble is my lens only goes to 200mm and thus I needed to crop to fill the frame with my subject. That's why I recently changed from the 12mp D300 to the 16Mp D7000 those extra pixels make a difference.

-dsc7242-x-x.jpg


Oh on another point about using image stabilisation, that Nikon document confirmed that it should be turned OFF for faster shutter speeds

Quote:The D3 supports vibration reduction with VR lenses. Turn vibration
reduction off when shooting at fast shutter speeds.
Other vibration reduction settings may result in slower
frame advance rates and increased shutter lag.


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