Autofocus fail for distant subjects. 7D2+5D3 (1 Viewer)

jack2964 said:

I am grateful for anyone to share their knowhow and experience with distant subjects. I know for sure at where I am shooting, I won't be getting sharp and fine feather detail images. However when I am in a hide shooting birds at about 4 to 8 meters and in reasonably good light I get decent results.
Browsing the many images on the net I am envious of guys who capture great BIF images with great detail and sharpness and I often wonder how far their subjects were.
I don't know about your Nikon gear so I can't comment. But I wouldn't be surprised if other brand cameras+lenses would face the same limitations. To resolve fine detail at long distances would require a very large diameter objective lens (think astronomical telescopes).

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Barred Wobbler said:

If the focus point moves even a fraction from the subject the 7dii focus is so rapid that it will grab the more interesting background behind the subject. I’ve had the same problem for years and the fault doesn’t lie with the autofocus, but with the accuracy of the pair of hands that is tracking the subject.

I’m once more in Spain in the Tarifa area for the autumn migration. Often the birds are distant, but often they are very close indeed. Against the sky it is fine, but against a hillside it’s a nightmare, because no matter how hard you try the wind will cause the bird to deviate or the momentum of the lens will carry it just that fraction off target to allow the lens to refocus. In previous years I would pat myself on the back if I got a handful of focussed shots of, for example, a booted eagle flying past into the wind at a range of 50m against a hillside a hundred metres behind it.

This year I have found a solution. I use a sigma 150-600 sport and the sigma dock allows for customisation of focus settings. Before I had C1 set to 2.8 to 20m for the likes of close passerines and C2 set to 10m to infinity for fliers and distant stuff. A couple of months ago with this trip in mind I had a brainwave and reset my C2 to limit it to about 120m maximum. This also has the advantage of stopping me getting carried away and photographing approaching raptors at too great a distance. It has worked a treat. Where before I was hitting focus on one in ten or less, today I was tracking honey buzzards, eagles, kites and Egyptian vultures against a hillside and was failing to focus on maybe one in ten. The vast majority were spot on or almost so. If the wind buffeted the bird I might miss, but a pump with the thumb on the focus button found it again.

If I really need to focus on something over 120m, then I just set the custom switch on the lens to ‘Off’.

It’s been a revelation on this trip.

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jack2964 said:

I don't know about your Nikon gear so I can't comment. But I wouldn't be surprised if other brand cameras+lenses would face the same limitations. To resolve fine detail at long distances would require a very large diameter objective lens (think astronomical telescopes).

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Barred Wobbler said:

Now that I'm back home and I've seen the results on my computer I might have been slightly over the top with my estimate of keepers over missed shots, but not by much. It's an order of magnitude or more better than the old infinity setting I'd been using on earlier trips. I've got dozens of shots like this of honey buzzards, booted eagles, black kites, short-toed eagles, Egyptian vultures, griffon vultues and even a few sparrowhawks from the trip.

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HermitIbis said:

I've discussed long distances elsewhere. Digiscoper Neil Fifer gave the advice to shoot birds rather 30m than 100m away. Danny Young / nzmacro, who focuses his FD 500mm or FD 800mm manually via Nex-7, wrote: "I would never use anything at a 150 meters, not even the 800 F/5.6L".

For close birds, say 7m away, feather detail isn't hard to get. A bridge camera like the Canon SX50 can do it for stationary birds. The SX50 is still an option for 100-150m distances - until the birds take off. With 2-3 frames per second or speeds below 1/1000 sec it is hopeless to shoot raptor action.

I am interested in bird behaviour. Feeding goldcrests can eat 8-12 springtails per second. Sometimes we need a fast camera! Feather detail is not my goal, if I shoot raptors in a distance, but IQ is important. It would be nice to have a 500mm prime and your reach of 1120mm equivalent (vs my 800mm).

Fortunately I have an upgrade path to 2295mm, if I win Euro 1000 in a lottery. o

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Dave Harris said:

Whilst on this subject. My Mk2 won't shoot when the target isn't in focus (eg a distant dot). Seem to recall a setting for this but can't find it anywhere! It almost cost me a distant Cattle Egret a couple of weeks ago. Anyone know how to disable this feature?

Cheers
Dave

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