oldtigger Loc: Roanoke Virginia-USA

give or take 3 meters does seem more realistic than .005 meters.

I don't have LR, any other stand alone extracters that might work?

oldtigger Loc: Roanoke Virginia-USA

give or take 3 meters does seem more realistic than .005 meters.

Apaflo Loc: Anchorage, Alaska

There is no focus averaging.

The OP is talking about a Nikon camera. Nikon cameras can have many "focus points", but only one of them is selected to measure the focus. There is no averaging, ever.

Rongnongno Loc: FL

READ ABOVE!

ONE Focus point BUT the result of an averaging. Stop spreading you brownish misunderstanding.

Apaflo Loc: Anchorage, Alaska

Exiftool is the best, but while it will indicate that the distance is meters on some cameras, it doesn't on others. And they will virtually all say 84.14 meters.

But heck, try in on a wide angle lens and it might be plus or minus 10 or 20 meters!

Apaflo Loc: Anchorage, Alaska

Read what was written. The "focus point" is internal to the camera, there may be 51 of them, for example, that show up in the viewfinder. The viewfinder square is the "point" that is selectable.

Only one point is selected for use in measuring the focus. And the focus of course is only at one single plane.

But let me repeat that again until you blow a cork and give it up:

There is no averaging done with focusing. One one point on the sensor is used. Read any of the Nikon user manuals and it will tell you that.

Rongnongno Loc: FL

I will not describe what I think of your understanding of how the averaging works. Your understanding is wrong and since you are not able to back down, even knowing when you are mistaken you keep going like the infamous bunny.

Enjoy your lack of brain cells, you already enjoy being obnoxious most of the time so...

YOU WIN! (not)

(indistinct rumbling)

SonyA580 Loc: FL in the winter & MN in the summer

EXIF data says the was "1.33x Digital zoom" on second shot. Could that cause the blur??

Apaflo Loc: Anchorage, Alaska

If you are right, find anything where Nikon says that is what their cameras do. Anything!

Look in the manual for the D800, for instance. Auto Focus points are explained starting on page 93. No mention of any kind of averaging.

For Single-point AF it says "the focus point".

For Dynamic-area AF it says "the focus point". Then is says it will use information from the surrounding points, if the subject moves. It does not say anything about averaging, because the information is used to select a single focus point that is where the subject has moved to.

For 3D-tracking it is similar to Dynamic-area but is more precise in describing what it does. It specifies that when the subject leaves one focus point it is tracked and new focus point are chosen as required. A single new point when the subject is not under the previous one.

Auto-area AF automatically detects a subject and selects the focus point. The clincher is this one: "The active focus points are highlighted briefly after the camera focuses; in AF-C mode, the main focus point remains highlighted after the other focus points have turned off." That is the one single focus point that was used for actually focusing. Note that there is no suggestion of any kind of averaging.

On page 94 it even describes what it means by "information" that is used from other focus points for tracking: "colors in the area surrounding the focus point are stored". That's is how it knows which new focus point to select for focusing if tracking is necessary. There is no focus information from other than one single focus point that is selected.

On page 95 there is a chart that specifically states "Only active point is displayed in the viewfinder. Remaining focus points provide information..." Nothing about averaging. One point only.

End of discussion.

Howard5252 Loc: New York / Florida (now)

I was trying to ascertain if the image would suffer while using the 2x telextender - and if so, would it be acceptable? I will do the test over again.
The lens is the Nikon 500mm and has a VR setting on it for TRIPOD. Of course, that is my default setting since I'm never going to hand hold this monster.

JoeJoe

Single point focus is what it says on the tin....
An important question is...Is your lens calibrated correctly to your camera... older Nikons back focussed but can be manually corrected, extenders will add softness to an image and also generate more handshake so shutter speed has to be doubled to compensate... ie..1/200 @200mm 1/400 @400mm and on and on..along with recalibrating the lens to the specific body when adding the extender (reduces softness). I will calibrate my lens once a month to the specific body they are on.. it does help and reduces out of focus shots. Do not mistake WB for Focus averaging..

oldtigger Loc: Roanoke Virginia-USA

brings up a question, if a zoom needs to be focus calibrated at the zoom range it will be used, does a zoom plus extender also need to be calibrated?
Or do we just assume adding the extender changes nothing?

Howard5252 Loc: New York / Florida (now)

It's not the second shot that's blurred but still a good question! On my next test I will try various combinations of telextender and digital zoom and compare them to a "straight" shot with lens only. I WILL take notes.

JoeJoe

Anything in between lens and sensor needs calibrating to the body the fittings will give slight differences....shims used to be used nowadays higher end cameras allow fine tune... older cameras on the allen key just inside the box near the sensor... just a bit of common sense really ... and not confusing WB with focus...
WB uses average to create 18% grey
Focus uses a contrasting edge to gauge distance then converts that to your lens to create 1/3rd DoF in front of object / subject.

oldtigger Loc: Roanoke Virginia-USA

i don't think much of anything is correct in that sentence.