SharpShooter Loc: NorCal

I will assume if your camera is made for that type of photography, then it is equated with spit focus. If so you shouldn’t have any trouble with focus, assuming your lens is well calibrated.
Also, why does the grass only wave in front of the birds eyes but not his shoulder?
Using the correct gear will yield the best shot possible.
Many are just h*ll bent on using the wrong gear for the wrong job. Your chances increase when you reverse that. That includes everything from the camera to a moveable blind to wearing the correct camouflage.
SS

CamB Loc: Juneau, Alaska

I downloaded and printed your chart, set up my tripod, followed the directions and went through all the tests on four different lenses. All my lenses were right on the marks. Yea!! Thanks for putting this out. I've been meaning to do this for a year.
..Cam

cameranut Loc: North Carolina

The downloads aren't bad at all considering the circumstances. They don't exactly pose do they.
Did you do any pp on these? The top photo when lightened up a bit and sharpened looks good to my old eyes.
Some sharpening will make it appear to be more in focus, of course that will add noise.

bdk Loc: Sanibel Fl.

what I did with my 810 and Sigma 150-600 : I picked an item to shoot ( a mail box) and practiced with different ISO, F stop shutter speeds and everything else I could change. Its not a fix all because of different lighting etc in different situations but it was a good starting point to get used to the lens. Which is a great lens when everything works together.

bobfitz Loc: Kendall-Miami, Florida

I agree with those who say focus on the eyes. In this case I see it as a challenge to AF and might try manual focus. If that didn't work I would calibrate the lens focus. I shoot with the 7100 and love it. Your manual tells you how to calibrate your lens as well as many videos on the subject that are available on YOUTUBE.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

If you look at the OP's gear, you'd realize that F4.5 is not an option. ISO 1600 is, however, especially on the D600. With an EV of around 9, 1/800 at a lower ISO with a lens that has a max aperture of 6.3, or a combination of a lens and TC that has a max aperture of F5.6 but would be better if it was closed down to F8 - you aren't quite understanding the shooting conditions. Also, one of the amazing shots is when one of these majestic birds takes flight - which is really hard to get if you are anchored to a tripod. With wind blowing, you don't want to risk 1/60 second. Do you have an examples of bird shots you have taken at F8, ISO 400 and 1/60 sec?

With birds, they are all grab shots - these cannot be easily planned for. Owls don't blink much, but they do squint a lot.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

That's nonsense - if you are shooting birds. The focus sensor usually covers the entire head, or head and shoulders - if you are shooting at distances that would not make the owl fly away - usually 40-60 yds.

camerapapi Loc: Miami, Fl.

"Oh, is THAT all, William?

Still ... it did the trick, didn't it?"

It seems better to my eyes and yes, only a curve adjustment and some sharpening.

camerapapi Loc: Miami, Fl.

"That's nonsense - if you are shooting birds. The focus sensor usually covers the entire head, or head and shoulders - if you are shooting at distances that would not make the owl fly away - usually 40-60 yds."

In total agreement.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

You have a really difficult set of constraints. Kayak and grass moving are not easy conditions to shoot in, but not impossible. The nice thing is you can likely get a little closer than you could if you were on foot.

The only things I can suggest, not being there and making decisions on the spot in response to specific conditions, is to use a full frame camera with great high ISO performance - Nikon D4 or D5, Canon 5DMk III or IV, etc., use a fast lens, F4 or better for faster AF acquisition, but make sure you stop it down to F8 for better DoF, and make use of the AF-L - I have it programmed to lock focus on the shutter half-press, using the AF-On button to actually acquire focus. I use a Nikon that has GroupAF that is very effective when tracking a moving bird against a background, or AF-C drive with single point, release priority if the sucker is perched or wading. Ideally focusing on the eye is a good goal, but rarely am I close enough to get just an eye to focus on. If you use 1/1250 or fast shutter, and the ISO high enough to allow that, you will be getting some keepers. You'll have to post process as much as you can to enhance contrast and microcontrast to bring out medium details. And of course, use the best lenses you can afford. The Tamron 150-600 G2 and the Sigma 150-600 Sport are pretty decent and very similar in image quality - though I think the Tamron is a little better at less than 600 than the Sigma, and possibly a little sharper wide open at 600mm as well. But I am splitting hairs - both lenses are great. I bought a used Sigma Sport for $1200, and the going rate seems to be $1100 to $1300, depending on condition. The Tamron is available for $1300 with that $100 rebate, which makes it a great deal. The Tamron has a big weight advantage, coming in at almost 2 lbs less than the Sigma. My frame of reference is my 600mmF4 AFS II, which takes amazing pictures, but weighs 10-1/2 lbs and cannot be hand-held. The G2 and Sport are just as sharp, or damned close, at F8 as the Nikon.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Almost impossible to manually focus with the simple ground glass that most cameras use for a focusing screen these days. The focus indicator does help, but when you use it you have to switch focus from the image on the screen to the indicator and back, and you will miss shots.

bobfitz Loc: Kendall-Miami, Florida

The hardware is almost never the issue for those of you who spend megabucks on gear. Knowledge, preparation and patience will beat pricey gear any day.

camerapapi Loc: Miami, Fl.

"The hardware is almost never the issue for those of you who spend megabucks on gear. Knowledge, preparation and patience will beat pricey gear any day."

In total agreement with this too.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Camo doesn't work with birds -the have visual cortexes that are highly tuned to detect movement, distance, speed and size. They have a disproportionately high number of M-retinal ganglion cells, which are color insensitive and largely pattern insensitive. But they can help a raptor spot a rabbit running in the grass at 3.2km. They also have P cells and K cells that account for some shape and color (pattern) discrimination, but nothing compared to their eagle-eye motion detection made possible by the M-cells. A blind can help, mainly because it doesn't move. But the camo is totally useless.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

You'll miss the shot while you care calculating. Besides, how often do you carry a 100 yd measuring tape. Seriously, go out and take some bird pictures before you give advice. See how close you can get before the bird books.