My take on CAM 2000

I got to thinking about this AF-C and Focus/Release Priority thing and I want to go into my thinking in greater detail, only because the context of this thread is educational. I'm not saying my way is the only right way, I only want to explain my logic so people can come to an educated decision.

I started with a D70 and I quickly learned the value of a dedicated AF-ON button, especially in AF-C mode. I think the major shortcoming of the D70 is the fact that you can NOT shoot AF-C focus priority. For me, that is critical and when I got a D2H I thought I died and went to heaven. I used the D70 as a 2nd body and I use it with a dedicated AF-On button, but I can't shoot it the same way I shoot the D2H and that bothered me at a variety of levels. I recently bought a D200 and one the main reasons I went to that expense was to make my 2nd body work just like the D2H- dedicated AF-On and shooting in focus priority with a built in mechanism allowing me to do focus/recompose.

I think that shooting a D2 series body in Af-C release mode as default cripples the body almost to the level of a D70 CAM900 relative to what a D2 CAM2000 body can potentially deliver. The only real difference is the inherently better speed and accuracy of CAM200 makes the entire issue somewhat less critical, but it doesn’t make it go away. Here's why.....

Much of what I am going to say is dependent on your subject and shooting style, but I am using a worst case situation here, which is typical of my shooting, where either my subject is moving, often erratically, and/or I am hand holding the camera, adding small but critical erratic movement relative to what the AF sensor sees and precisely what the sensor is actually focusing on.

When I focus in AF-C mode, I typically see the focus confirmation dot blinking on and off, and I usually hear my lens focus mechanism chattering in response to repeated and continual commands from the AF engine. I assume my experience is common.

We have two very fast and responsive systems that ideally should work together: when I press the shutter, the camera fires instantly with no hesitation. More importantly, the AF engine is constantly re-computing it's focus distance and it is responding to every twitch of my body and/or every twitch of my subject. When you shoot release priority, those two systems are totally out of sync. You are rolling the dice as to whether or not your shot will be precisely (and I mean precisely) in focus. You may get acceptable results either way, but certainly if the shutter fires when the confirmation indicator is off, your image will not be as sharp as it could have been and you didn’t get all of your money’s worth from your very expensive camera body and lens.

When you shoot focus priority, you are adding a tiny, usually imperceptible delay that allows these two very advanced systems to work together as designed.

I will be the first to admit that after my initial excitement over the AF-C/Release Priority feature, I slid back to release priority because of the issues of focus/recompose. But over time I have come to appreciate the engineering effort that Nikon put into the positioning and programmability of the Af-ON and AE-L/AF-L lock button, as I discussed in a previous post to this thread:

“… the solution, which is to set the AE-L/AF-L button to lock focus, and then do a thumb roll to the AE-L/AF-L button when you are ready to recompose. I think the AF-ON and AE-L/AF-L buttons have their peculiar angle and close association specifically to facilitate this thumb roill and I have spent a bit of time trying to perfect the technique so that I can do it quickly without thinking too much”.

I believe the camera was designed specifically to make all this work smoothly (including Focus/Recompose!!!) in AF-C/Focus priority mode because without that engineering, much of the technological "magic" of the CAM2000 system goes to waste. You don't need the sophistication of the CAM2000 system as a whole just to get an eyeball in focus for a studio portrait or a tree in focus for a landscape. That system was designed to shoot anything, anytime, anywhere, with the highest probability of getting it in focus that the mind of man can engineer. But to make that work most efficiently, the system needs to be in focus priority. This is my opinion, of course, but it an opinion formed after shooting tens of thousands of frames of dynamic subjects over a two year period while going back and forth between the release and focus priority modes.

I'm not arguing that any given shooter should shoot the way I do and I also recognize that one fixed size control interface may not work as well for all hand sizes and shapes. I do think that Jason should put a very condensed version of the above into his tome for completeness.

Most importantly, Tom’s post above implies that the camera was not engineered to perform focus/recompose while in AF-C focus priority mode. That is a common misperception but is simply inaccurate and I think it is a very fundamental and critical point that affects every shot we make. I will also be the first to admit that doing the “thumb roll” was not an easy thing for me to get used to but the effort paid off because I believe I now get the most out of CAM2000 that it has to offer.

--
Regards,
Neil

--
Regards,
Neil
 
No complaints here. I say do whatever works. I will mention that the blurry example I shot on my article (focus point between two objects) was done in AF-S mode with release set to focus priority. The camera can still be fooled.

-Jason

--
Jason P. Odell, Ph.D.
Author, 'The Photographer's Guide to Capture NX'
http://www.luminescentphoto.com/capturenx.html
Holiday discount for dpreview readers:
http://www.luminescentphoto.com/dpreview.html

Co-host, 'The Image Doctors' at Nikonians Podcasts
http://podcasts.nikonians.org
 
http://www.naturephotographers.net/articles0606/ee0606-1.html

drawing attention to the size of the AF detection areas and the potential pluses and minuses.

On a point of minor detail the horizontal detection areas are shown as a little wider than yours - as they are on my F6 which also uses CAM 2000.

At the moment my bank balance cannot justify a D2xs in addition to the D200, but the major point is if a D2x, D2h, D200, D80 and F6 is aimed at a not so good AF target and there is a good one outside the viewfinder mark AF can choose the good target - even if it is at a different distance to what's in the center of the viewfinder.

--
Leonard Shepherd

Usually skill in using equipment has more to do with good photography than the equipment itself.
 
My take on your example of the focus sensor splitting the difference between two points is that it is a completely different issue and probably unrelated to focus/release priority. I think I have seen this effect but never understood what the camera was doing.

I just assume that over the course of many images, focus priority will result in a greater yield and that is my experience in real world use. I don't think it is possible test it with individual images because the result depends on the dynamics of the focusing system at the exact instant that the shutter opens.

Like most people using a D2 series body, I have a huge investment in bodies, glass, tripods, etc. etc. I want to squeeze everything I can out my investment.

Because of that I worked very hard to integrate focus priority into my shooting work flow.

--
Regards,
Neil
 
I've been following this thread with great interest.
because of the issues of focus/recompose. But over time I have
come to appreciate the engineering effort that Nikon put into the
positioning and programmability of the Af-ON and AE-L/AF-L lock
button, as I discussed in a previous post to this thread:
“… the solution, which is to set the AE-L/AF-L button to lock
focus, and then do a thumb roll to the AE-L/AF-L button when you
are ready to recompose. I think the AF-ON and AE-L/AF-L buttons
have their peculiar angle and close association specifically to
facilitate this thumb roill and I have spent a bit of time trying
to perfect the technique so that I can do it quickly without
thinking too much”.
Could you please clarify this "thumb rolling" technique? How is this different from locking the focus by releasing the AF-On button? Thanks.
 
If you are shooting AF-C/Focus Priority and you release AF-ON to recompose, you can't release the shutter because you no longer have focus. That is the basic problem with this mode.

If you put your thumb between the Af-ON and Lock button, with the flat of your thumb pad (rather than the tip of your thumb), you can roll your thumb right to press AF-On and then simply roll it left to lock focus. You have to experiment with this to see exactly where the sweet spot is that allows you to do the roll. I have small hands and a small thumb. It may be different with large or different chaped hands and thumbs.

Did this make sense? You have to try it on a D2X or D2H as you read this.

--
Regards,
Neil
 
If you are shooting AF-C/Focus Priority and you release AF-ON to
recompose, you can't release the shutter because you no longer have
focus. That is the basic problem with this mode.
Thank you. I think I got it.

Please correct me if I'm wrong. The primary advantage of this technique is not so much the ability to acquire accurate focus in the focus/recompose situation. That is, focus accuracy is more or less identical whether you use focus priority (thumb rolling for focus/recompose) or release priority (release AF-On/recompose). However, if you set the camera to "AF-C release priority" (so that you can do focus/recompose in AF-C), you are underutilizing the potential of AF-C when tracking a moving subject, for which AF-C was developed in the first place.

I hope I'm understanding this correctly. I'll try to see if the thumb-rolling technique is faster than reaching to the AF servo switch to change the mode to AF-S. I've at least got a decent sized thumb so the technique wasn't too uncomfortable in my first try.
 
The third setting is the release priority+focus. Has anyone thoroughly tested this setting and compared it with the other two modes and the various combinations with AF-ON? I wonder why Nikon put this mode in? It must have a purpose.

It is very hard to run systematic tests with AF-C etc. because the situations we encounter in the field vary so much. I have tried it, but really so far have not arrived at any conclusions.

http://www.heisingart.com
Fritz
 
The third setting is the release priority+focus. Has anyone
thoroughly tested this setting and compared it with the other two
modes and the various combinations with AF-ON? I wonder why Nikon
put this mode in? It must have a purpose.
I have used FPS+AF and my experience is more or less consistent with what little Nikon divulges about this mode. It slows down the camera just a tad, and it probably results in better focused images...
It is very hard to run systematic tests with AF-C etc. because the
situations we encounter in the field vary so much. I have tried it,
but really so far have not arrived at any conclusions.
This is like arguing politics and religion, but I personally don't think any of this could be systematically tested. You might, at a great expenditure of time and possibly money, concoct some sort of test with some object moving at some consistent rate of speed at some angle to the camera, for example, but that would only represent one of an infinite number of real world possibilities.

My experience tracking birds in flight and people on horses, for example, is that the AF seems to move in fits and starts, it does not seem to synchronously track the object in infinitely fine increments. Release priority tends to yield something well under 100% when I run a high speed set. Sometimes the AF is behind and sometimes it is caught up.

If I had a situation where I thought focus priority would not yield a high enough frame rate, I would want to use FPS+AF and that works in a focus/recompose mode without using the lock button. It's half way in between in some twilight zone. Maybe Jason has some thoughts; I'm surprised he doesn't use this as a default, just based on the discussion here.

I think it is a shame that the critical AF option selections, such as the Single area/dynamic options, and the focus/release options, really all the AF menu options, are not embedded in the EXIF. I go out and shoot 1000-1500 frames a day on a good birding day. Sometimes I change options because things obviously aren't working for me, but when I get home, I am never 100% certain what I had set for each and every image. If I had that exif data, I think I could make much more educated decisions.

Now on to the serious religion part... here is the way I look at it...

I spent a small fortune on a D2H. I spent another small fortune on a D200. I spent all that money to get the best I could possibly afford in terms of a camera body, especially in terms of AF performance. I want that last 5% in performance.

I have two Gitzo tripods and a Markins M10 ballhead. That was serious money but I wanted the last 5% in performance from my tripod.

Now my glass. I have a 300 F/2.8 AFS II, a 300 F/4 AFS and 70-200 VR. These are my main "action lenses". I spared no expense, in their class, to get the last 2% out of that glass. That was more than a small fortune.

I now have at least three small fortunes tied up in gear, all directed towards getting the last 2-5% performance from it.

Now, it's down to technique and I have a choice. I can use the method that, at least according to the manufacturer, is intended to only fire the shutter when the camera sees perfect focus. Or, I can use a method that, by design, doesn't care if the camera is in focus or not. In order to use that second method, I have to take a HUGE leap of faith, assuming that AF-C is fundamentally so fast that the results will be the same even if the camera doesn't care if it is in focus. Or, I have to try to evaluate that which is impossible to evaluate with any factual basis- what are the odds, in any given specific situation, that release priority will really keep up?

After spending all that money, do you want to take that leap of faith? I don't think that would be consistent with all the expenditures that preceeded it.

To be clear, on a static subject, it probably doesn't matter too much and, it is easy to see how good a focus lock you have from the confirmation light and lens chatter- for most lenses; my 70-200 VR behaves differently. I am only talking about moving targets where there is no time to assess the AF accuracy.

And, for me, I have SEEN the difference between focus and release priority. The real world difference between focus and focus+release is less clear to me, from actual use, but I just want all the last 2% odds I can get. I view this as my final 2% improvement.

One more thing, philosophically, I ideally want to shoot just one way, with as few changes to my configuration as possible when I am out shooting. The M/C/S button is out of sight, out of mind, on the front of the camera body. The focus/release option is buried in a menu, out of sight, out of mind. Back when I was working all this out, I constantly blew shots because something out of sight, out of mind, wasn't set the way I thought it was. I'm a little forgetfull. I'd rather pick one method, make it work for me in as many situations as possible, and stick with it. I don't want to be in a position where I'm in AF-S mode and all the sudden I see that Eagle strike the goose in mid-air and the feathers are flying.

And, once again, we are "arguing" religion here, not statistical facts.

--
Regards,
Neil
 
For this very thorough response. I think you are right, there is no clear conclusive all in one solution to the original question. I am not surprised. I also have spent a small fortune on my equipment and want to squeeze the last few percent of performance out of it. But, I have to say that I enjoy the challenge and even the inconclusiveness. Like you, I tend to forget to check some of the settings from one shooting to the next and as you say, the EXIF date don't include them.

I am preparing checklists to go over at every setting and try to establish a drill for myself to be aware at all times of exatly how I have set the various options. If nothing else it is a good exercise for mental awareness.

In a strange way this kind of photography (birds in flight) is rewarding in many unexpected areas. For example, not only do we become more aware of the strenghts and short comings of our equipment,and ourselves, but we also learn about the behavior of the animals.
All in all, a very fascinating field of persuit.
Thanks again, and Merry Christmas.

http://www.heisingart.com
Fritz
 
If you are shooting AF-C/Focus Priority and you release AF-ON to
recompose, you can't release the shutter because you no longer have
focus. That is the basic problem with this mode.

If you put your thumb between the Af-ON and Lock button, with the
flat of your thumb pad (rather than the tip of your thumb), you can
roll your thumb right to press AF-On and then simply roll it left
to lock focus.
Neil, out of interest, why the need for a complicated (and maybe slightly awkward) "roll" method? Why not just have your thumb squarely over AF-ON to focus, then lift, move, and press AF-E/L to lock focus, then shoot? Maybe it's speedier your way? But if you are anyway having to recompose (and that's the point of this method -- focus and recompose), then in the time it takes to recompose, your thumb can easily have made the short journey between the two buttons. Maybe your method also ensures your thumb actually find the AF-E/L button, but with a bit of practice I can't see it being too difficult to find it consistently even with a lift/move method? Not saying your method is not necessary, I'd just like to be enlightened as to why it is!

Cheers,

Mike
 
then in the time it takes to recompose,
your thumb can easily have made the short journey between the two
buttons.
Mike- you cannot overlap the button change motion with the focus recompose, otherwise by the time you press the lock button you likely no longer have focus. When in focus priority mode, I believe you must have focus at the instant the AE-L/AF-L lock is pressed. The slightest movement of the camera could lose focus lock, depending on your focus target.

I suggested the thumb roll because I personally find it faster, more reliable, and LESS cumbersome. I suspect that much of the reluctance to use AF-C/Focus Priority is because most people do a thumb lift instead of a thumb roll, and it doesn't work well for most people. Otherwise I think it would be a more accepted method. After all, in most cases, you give something up by going to a release priority mode.

I first tried your method, lifting my thumb from AF-ON to the lock button, but I found that for some reason it was cumbersome, and I frequently lost focus lock, losing the image. That is when I figured out the ingeniousness of the button layout, at least for me.

YMMV, and you should do whatever works for you.

(I am now shooting with a D200 and D2H; I wish this button layout had been built into the D200 because I have to do it your way; no way to do a thumb roll).
 
Mike- you cannot overlap the button change motion with the focus
recompose, otherwise by the time you press the lock button you
likely no longer have focus. When in focus priority mode, I
believe you must have focus at the instant the AE-L/AF-L lock is
pressed.
That doesn't seem to be the case, at least not here. You can happily let go of AF-ON, recompose, hit AF-E/L, and shoot -- even if the focus point is no longer in focus when you hit AF-E/L.
I suggested the thumb roll because I personally find it faster,
more reliable, and LESS cumbersome.
Maybe so. I'm still adjusting from the D70 where there wasn't even an option of having focus priority on AF-C, and where there was no dedicated AF-ON button (just the AF-E/L programmed to AF-ON), so I'm now spoiled for choice!

Thanks,

Mike
 

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