A1 bird eye AF - does it add anything?

[Ziggy]

I've tracked this issue across multiple forums (Fred Miranda, DPreview, Feathers and Photos, FB) and extensively used the A9 and A7R III that clearly use similar algorithms. On-sensor PD gets confused regularly by small static birds.

The term 'confused' is used by the local Nikon/Sony/Canon service agent.

Note that I didn't say it can't function but that it's not reliable. Focus racks out but no AF point is recorded in EXIF.

Sony AF weaknesses - A9, A7R III

There appears to be 3 types from my experience (now 6) and others' posted here and elsewhere:1. Flat failure to get a lock (usually experienced wi...

www.fredmiranda.com

https://m.facebook.com/groups/sonya9/permalink/2606391359453112/

 

[Doug Herr]

I've tracked this issue across multiple forums (Fred Miranda, DPreview, Feathers and Photos, FB) and extensively used the A9 and A7R III that clearly use similar algorithms. On-sensor PD gets confused regularly by small static birds.

The term 'confused' is used by the local Nikon/Sony/Canon service agent.

Note that I didn't say it can't function but that it's not reliable. Focus racks out but no AF point is recorded in EXIF.

Sony AF weaknesses - A9, A7R III

There appears to be 3 types from my experience (now 6) and others' posted here and elsewhere:1. Flat failure to get a lock (usually experienced wi...

www.fredmiranda.com

https://m.facebook.com/groups/sonya9/permalink/2606391359453112/

Tracking the issue on internet forums and using the camera are two very different things. Likewise tracking the issue with the a9 and a7rIII and extrapolating to the a1 is quite foolish. This isn't anywhere near my experience with the a1. The a1 reliably finds the bird and locks onto the eye; it can be a small static distant bird, or a bird partially obscured in the brush, or perched on a very detailed high-contrast tree trunk, or the erratic flight of a hummingbird.

And no, DOF does not get the eye in focus if "the head" is in focus. DOF at close range for a small bird is negligible; only part of the head will be in focus. The a1 does struggle with a fast erratic tiny bird at close range in poor light with a dark eye and dark plumage (example below) but the struggle is relative: the vast majority of the time it locks onto the eye in less than a second in this scenario. The a1 with bird eye AF enabled has easily been the most productive camera I've ever used for bird photos.

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[Doug Herr]

So, the way I see it with the Eye AF, is that yes, it's looking for a specific shape to lock onto, but I think it may be slightly faster still if it were just looking for any part of your subject to lock onto. I do not question that it's impressive, and very clever, and definitely appeals to a great many, but I've been shooting for 40 ears and never had it in the past, and have always managed birds in flight without. I would even say that my old Minolta 700si was as good as anything now at acquiring focus on a flying bird. I didn't miss many!

The bird Eye AF first finds the bird, then finds the bird's eye. I've been photographing birds for 50 years and the a1 with bird eye AF enabled is by far the most productive camera I've ever used.

 

[Ziggy]

Tracking the issue on internet forums and using the camera are two very different things.

I was doing both - the first in order to make sense of a weakness I found on first and continued use of the A9 and then the A7R III. I found plenty of others had had the same experience, including with the A7R IV.

Likewise tracking the issue with the a9 and a7rIII and extrapolating to the a1 is quite foolish.

If you took the care to read the posts, you'll see I was responding to Kevriano's generalisation about the A7R IV. One swallow does not a spring make; one success doesn't equal reliable performance. I can get a string of successes followed by a string of failures.
That's the problem with the bodies I was referring to. They're not reliable in this use case so they can't be recommended for those taking record shots. They're fine for BIF if still not quite as accurate as the best module PD.

 

[garuda]

.... A7Rs are not good at is locking onto a small static bird....

My consistent experience w 7Riv is: simply place target at center and hold down AF-ON button. Totally locks-on quickly, especially w 135GM. Then I can (and do) move the FoV to where I want the target to appear (1/3s) in the frame. For my settings, it works consistently whether mode is Wide or SmCtr. I have difficulties understanding arguments contrary to this (at least for Riv's -- don't know a9s).

.... Doug's experience appears to indicate that the A1 does better....

Obviously it has been shown that the a1 is better in many areas (at least somewhat in several, much better in others). But to claim a1 does the AF Lock-on better than R7iv --- I hope they mean in terms of speed of acquisition only. Because to me, it either works or it doesn't, in terms of locking on. When my AF-ON locks-on (in milli-secs) it won't let go, so long as locked-target stays in FoV regardless of mode, and I shoot a lot of Wide. On acquisition speed, the a1 may have an edge. But for Lock-on specifically, 7Riv is like the proverbial steel-trap, at least in my experience.... consistently. And it doesn't matter whether it's a small stationary bird or a low-flying Pterodactyl.

 

[Ziggy]

And no, DOF does not get the eye in focus if "the head" is in focus. DOF at close range for a small bird is negligible; only part of the head will be in focus.

It may, it may not, it depends on the circumstances.

All of photography depends on the zone of acceptable sharpness (aka DOF). There is only one plane that will be in focus but there's an area in front and behind it that the eye (and the sensor) can't register blur in.

I wasn't talking about close range. You've added this as a condition. The AF failures people experience are in mid ground or further.

 

[garuda]

And no, DOF does not get the eye in focus if "the head" is in focus. DOF at close range for a small bird is negligible; only part of the head will be in focus.

I shot this today at 600mm, at 8 feet from Wren house (to test your theory stated above). And I used a low DoF to make my point (6.3 vs 11). It seems to me that both the head and eye are in focus to about the same degree. Maybe not perfect since I'm using a cheaper camera. And the bird it stationary at close range. Same shot, I cropped closer and closer for subsequent images.

I focused on head, not eye -- yet both seem the same focus. In fact, the entire bird seems in fairly good focus. You be the judge. And I invite harsh criticism if my images are not supporting my earlier statements.



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[Doug Herr]

I shot this today at 600mm, at 8 feet from Wren house (to test your theory stated above). And I used a low DoF to make my point (6.3 vs 11). It seems to me that both the head and eye are in focus to about the same degree. Maybe not perfect since I'm using a cheaper camera. And the bird it stationary at close range. Same shot, I cropped closer and closer for subsequent images.

I focused on head, not eye -- yet both seem the same focus. In fact, the entire bird seems in fairly good focus. You be the judge. And I invite harsh criticism if my images are not supporting my earlier statements.

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It looks like it was processed a lot, i.e., over-processed. Also the cheek feathers, near side of the eye and the bill are not in focus. IMHO this photo does not demonstrate the full capabilities of your camera.

 

[Doug Herr]

It may, it may not, it depends on the circumstances.

All of photography depends on the zone of acceptable sharpness (aka DOF). There is only one plane that will be in focus but there's an area in front and behind it that the eye (and the sensor) can't register blur in.

I wasn't talking about close range. You've added this as a condition. The AF failures people experience are in mid ground or further.

I haven't see the AF failures at mid-ground or further. In fact I've been favorably impressed with the camera's selection of the bird at distance.

 

[Ziggy]

I haven't see the AF failures at mid-ground or further. In fact I've been favorably impressed with the camera's selection of the bird at distance.

You haven't bothered to look at the links I posted.
Head, sand.
Welcome to my ignore list.

 

[Doug Herr]

Welcome to my ignore list.

Thank you! Please do the same on other forums. I'll gladly reciprocate.

 

[garuda]

It looks like it was processed a lot, i.e., over-processed. Also the cheek feathers, near side of the eye and the bill are not in focus. IMHO this photo does not demonstrate the full capabilities of your camera.

Grab a beer, another long one you hate reading:

Actually, I agree with you on one item, that is, the photo does not demonstrate the full potential of the 7Riv. It was hot today with no nearby shade, and I spent a short amount of time trying to freeze this quick-moving rascal feeding her hatchlings. And I wasn’t interested in capturing the perfectly focused image. But rather catching the bird stationary at a 90-degree angle to lens hoping to get the eye and head on nearly the same focal plane in order to determine your claim: “DOF does not get the eye in focus if "the head" is in focus.” And that’s all.

Sweltering heat prevented me from patiently waiting for the perfect AF when at perpendicular to lens. And for comparison purposes only (not for aesthetics’ sake), I did remove some noise and bumped the sharpness a bit to reduce blur enough to do the comparison between sharpness of eye compared to sharpness of head. It falls under the forensic umbrella for more accurate analysis.

And after inviting criticism, I’m surprised you didn’t notice that the entire bird is out-of-focus, not just the cheek and bill. But that’s not the point of this comparison. It was confined to your claim in testing whether the eye is in focus when the head is in focus. My conclusion is that both the head and eye are nearly equally out-of-focus.

Whether image is extremely blurry or pin-point sharp is beside the point. It’s the focal quantity comparison betw eye and head (based on your claim). But I compliment you on your skill at “misdirection” or “issue avoidance” by shifting attention away from the real substance of the issue or claim.

It’s beating a dead horse to argue this any further. You may be correct in your claim, but it was foolish of me to present any challenge regarding a point I could really care less about. Whether rightly or wrongly, I still believe the AF algorithms can acquire the head faster than the eye, so I use the best DoF for nailing the head. And if it is any consolation, I feel like an idiot for arguing this issue since the 7Riv doesn’t have BEAF and I don’t own an a1. What was I thinking? The brain must get soft being out there in the blazing sun.

I thought I had rid myself of the legitimate title “village idiot"…. but maybe not.

 

[Ziggy]

I'm happy to engage with people with informed opinions. Not fanboys.