That is a lot to learn, test, and try.
I’ve spent well over two hours so far just trying to understand this:
@OXiDant, is there an explanation posted somewhere, which would slowly allow me to understand what you have posted? I need a good starting point.
I think this could help out.
https://improvephotography.com/47436/focus-⅓-photo-deep-depth-field/
And this one too:
https://lenspire.zeiss.com/photo/en/article/depth-of-field-and-manual-focusing
This video is only of interest to someone who intends to purchase or work with a Z9. It covers the autofocus capabilities of that camera and only the autofocus capabilities. Furthermore, it is already outdated, as firmware version 5.0 is now current.
From my point of view, this video doesn’t really help you as you are using a D780.
My point is that you won’t be able to use anything from this video for your work with your camera.
Furthermore, it has nothing to do with DxO products…
To answer that question the straight answer that it is especially you that have DSLR-cameras that need to understand this!!! We who have mirrorless cameras with new lenses can just forget about it unless you are one of these Sony-users that uses Sont LAEA2 or 4-adapters with a separate built in focusing mirror. Why there is microadjustment in Nikon mirrorless even I don´t understand.
Mike, thanks for this video. It might be the best explanation of these issues I ever have seen. I just miss one thing and he just seem to forget that there are actually three paths of the light in a DSLR and one single in mirrorless.
As I have told you before I once exchanged the standard matte focusing glass in one of my Sony DSLR:s to a SLR-style focusing glass with a combined microprism and section view that i bought from South Korea (split focusing view or whatever you call it in English).
With that glass i got a bunch of metal and plastic shims to be used to finetune the position of that glass in order to adjust the focusing even in the optical viewfinder. I guess most of you never heard of anything like this but it is very common when building machinery and fitting things together to meet tolerances of different sort. So, these shims are used even in DSLR-cameras to achieve that even the optical viewfinder is correctly reflecting the focus to the viewer’s eye. I can tell you it took a great deal of swearing to get that in place. All these conditions are definitely something you ought to know about.
Just be aware of a few other complications too:
Since it has got more and more popular to use zoom-lenses you also need to know that microadjustment does not fix focusing imperfections with zooms. Well if you tune in the compensation for 50mm on a 24-70mm zoom that will be the only focal length that might be correct. To obtain a proper calibration of a DSLR-zoom I guess Canon corrects them on up to 8 focal lengths if I remember that correctly and the same goes for Sigma i think. I once had their MC-11 adapter and their lens dock - so I have seen that.
A second problem might occur if for example sharing a pool of lenses or your camera might not be able to distinguish a Nikon lens from say a Sigma of the same zoom span. From what I know the cameras can´t handle two or more individual lenses - just one since they look up these configurations/compensations done on the model number and not on model+individual. Changing two or more identical lenses of the same type might give you totally unpredictable results since the camera just can hold one adjustment compensation per camera for each type of lens.
In fact my severe focusing-problems I earlier had with both KonicaMinolta D7D (that didn´t even have microadjustment and a bunch of Sony DSLR and SLT (Translucent mirror systems) was almost getting me to totally give up photography. These DSLR and SLT-designs needs proper calibration in order to work properly because the phase detect AF is designed mainly to be fast. Unlike the newer hybrid-AF that all mirrorless uses today that is dead accurate, a pure phase detect system have no clue at all if the lens really is focused on the main mirror since their focusing is adjusted against a separate focusing mirror and it also lacks completely the feedback that always find focus and a natural equilibrium against the main sensor in mirrorless cameras. In worst case a phase detect AF-system is “fast but wrong”.
So, when Sony released their first advanced mirrorless NEX 7, that had a slow but accurate contrast-AF I immediately understood that it promised to solve all these terribly irritating DSLR-problems that had almost driven me crazy - and it did!
Thanks; another dead-end street. I did a search for focus using the Z6 and D780, and this showed up. From what you’ve written, this is a dead-end street. I wasn’t searching for Z8 and Z9 software, just the Z6.
I wanted to see how this is done on the Z6, as that is the software and hardware installed on my D780. Yeah, nothing to do with DxO. I’ll keep searching, but I’ll avoid posting the information here. I’ve read that while the Z6 and D780 can’t track animal eyes, both are supposed to be able to track human eyes. I’d like to learn how to do this.
If I had purchased a Z6 rather than the D780, I would have the same ML components and technology in each of them.
You’ve given me a good idea - thanks - I ought to be searching for how do do these things on a Z6, and I’ll probably have a better chance of finding explanations I can follow.
Of course, on the D780, I’ll be using the rear screen, not the viewfinder, but for my purpose, that is fine.
My friend Ray bought a Z6, and hated it. Now he’s got the Z8 and he’s happy. I didn’t enjoy using his Z8, but given enough time, I might learn to enjoy it. After I win the lottery, of course. 
My brain, and my feelings, are that it is first and foremost important to have the head/eyes of the bird perfectly sharp, as best I can.
I then have a choice - based on depth of field, I can have the tail end of the bird sharp, meaning the background will also be sharp, or I can limit the depth of field, resulting in a blurry “back” of the bird, as in my photo, and a blurry background behind the bird.
My goal is not to create the best possible photo of “a bird”; it is to capture my best photo of the bird in its surroundings. To make a meaningless part of the bird sharper, I am ruining the effect I wanted to capture. The mud on the bird’s beak enhances what I wanted to show.
The next time I will capture two photos, one your way, and one my way, and then we can compare. Since you are almost always right, you’ve got a huge head start.
In stead of using third persons in a vague way all the time, can you also tell us why he hated the Z6 and liked the Z8?
George
After all of Mike’s demonstrations of ignorance about the purpose of this forum and lack of experience with mirrorless: even if his friend would explain that to him properly there’s close to no hope Mike could repeat it the same way. But a very high probability of another half dozen lengthy repetitive posts with absolutely no insights.
Indeed. What is more important is that you actually focus on the eye or, at least, the head. As you can see from my screenshot of that last shot, the only thing truly in focus was part of the bird’s neck and, as I explained, because you used f/5.6, you only got a DoF of less than 3", which is barely enough to get the whole head sharp, let alone the rest of the body. So you ended up with a 3" slice of the neck.
On looking at the EXIF data, I see that you used AF-C (so it looks like you were spraying and praying) and, as far as I can work out, you had the AF point in the middle of the frame - which explains why the camera decided that the neck, being closer to the centre than the head, was the right place to focus on, even though you supposedly wanted the head.
The focus acquisition speed is far slower than the firing rate of the AF-C mode, so you are going to get a lag between shots when the focus is trying to catch up. One reason I rarely use burst mode, even for moving subjects.
Focusing on a heron from above means you have a long way to go between the head and the ground. Most Herons are around 3ft tall so, to get just the head and neck in focus at 220mm focal length, you are going to need, at least, f/32 for an 18" depth of field, without sharpening the background too much. For just the head, you are still going to need around f/16.
Mike, you need to realise that DoF with long focal lengths is very restricted, compared with more normal focal lengths, so you are going to need smaller apertures than you are expecting to use.
Because of your amount of failures and misfits? 
Once you get the reason of the problem you can throw away the others. 
I was walking my doggie ( it’s a meat eating guinea pig size. )in a forrest nearby Apeldoorn on the Veluwe.
Every time i enjoy the fresh air, silence and bird sounds, the non trafic.
But photographic wise it’s boring.
Pineapple tree’s, leeftree’s small plants of green. Nearly nothing standing out.
(naturewise good because stranding out means detected and be eaten.)
I did a 7km walk after spending half a day in a garden shop.
So 15k steps that day but nearly non photograpic interesting views and objects.
I have more to see in my backyard of 6m by 13m.
At this moment two great tits are eating 5m away.
The nearest birds overthere where beond my 600mm lens.
Moral of the story.
Don’t lugg your camerabag along just enjoy the fres air and silence…
The Z6/7/f handles file count on exactly the same way as your 780.
Maximum 5000 files per folder or max numbered 9999 before it swop to a new folder.
My older D3s/D3x allows for maximum 999 files or highest numbered 9999.
I can’t see any problems with either 999 or 9999 count per folder. 999 have worked for ages and never caused any real problems.
You can always add time or anything else to the naming convention upon import.
Personally, I have my images organised in a folder hierarchy of…
-- Location or event
-- Year
-- Month
-- Day
As soon as I return from a shoot, I connect the camera to the computer and drag the files into an appropriately named folder.
My keywording app can see all the files at a given level, including those in sub-folders. So, I can easily “filter” by whichever level I need.
I don’t bother renaming anything because the file names are guaranteed to be unique in any folder.
I sent Ray an email to describe the problem in his own words. I think I understand what he told me, but you’ll get a better answer direct from Ray. He told me his Z8 fixed that issue.
My mistake. The actual wording (in Ken’s Z8 review) was:
" File numbers have three programmable letters (good), but then an underscore and only 4 digits, so it only can make 10,000 shots before file names repeat. At 120 FPS it’s trivially easy to make more than 10,000 shots in just a half hour of shooting sports, and now you have to keep all those images in separate folders because you can’t put two files with the same name in the same folder. Nikon needs to replace the underscore with a digit so we have at least five digits in our file numbers. Even LEICA’s pokey LEICA M9 of 2009 uses seven digits in their file names to prevent duplicates, and that camera barely worked at 1 FPS."
Mike,
Who the heck is going to put 10,000 images in a single folder? Try loading that into PhotoLab. Reviewing 10,000 images in a single folder is impractical even if the naming conventions are unique and meaningful.
Once again, a lot of useless theoretical information from Ken Rockwell which may be technically correct but of no consequence in normal real world conditions.
Even if you have the same file name in 10 different folders, what difference does it make. It’s not like you’re going to be searching for those unique camera created file names, unless you’ve got every one of those names memorized and know which one you want to see.
You got to stop wasting your time reading Rockwell and assuming everything he says is gospel. And you got to stop wasting our time by referencing him so much. If you really think Ken Rockwell is the man, then the first thing you need to do is stop shooting raw since he thinks it’s a waste of time. 
Mark
I use PhotoMechanic to provide customized names for both the files and the folders. This helps in finding things year(s) later. Works fine with PhotoLab.
This is more of a theoretical problem than anything else. No one with proper discipline will store more than such high numbers of photos in one folder as that will cause more problem on its own.
Culling, importing, naming, storing in DAM and post processing manages this.
It’s nothing worth mentioning at all other than in the manual.
For “BIF” (Birds in Flight) the trick seems to be to put the camera in high speed burst mode, and leave it there as you follow a bird during flight. This allows you to maybe find the one perfect shot within the hundreds you may have taken during that burst, to get that one perfect photo.
Easy to do - start shooting when a bird is about to “lift off” and continue shooting at the highest possible frame rate as long as necessary.
Steve Perry created videos about how to do this, with examples of how it worked for him. Here’s one example I viewed yesterday:
https://www.youtube.com/watch?v=NorCs0h_38U
The same issue occurs in sports photography, where you don’t want to miss the one best shot - just mash down the shutter button, and select later.
Who? Perhaps anyone who watches Steve Perry’s video, that I just posted. Steve also shows what to do with the gazillion images, to get rid of the majority of useless images. Others have suggested the same thing, and I’ve done it myself. How else do you get the “perfect moment” during a bird’s flight?
Ken Rockwell? Consider his audience who have neither the time nor the desire to do “raw”. Interested in buying a new or old lens? Ken is one of the very few people who likely posted a review of it. Put the name of the lens into a Google search, and Ken’s name usually pops up. Besides, Ken posts both the good and the bad, which most writers don’t. OK, will follow your suggestion, not much more from me about Ken. Curious, who do you consider to be a good source of unbiased information for photographic gear?