NikonGear'23
Gear Talk => Camera Talk => Topic started by: Pistnbroke on September 04, 2016, 08:09:06
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Now don't lets all get confused with back button focus.
What I want to do with a D810 is this .
I usually shoot AF-S half press and then release .For about 20 seconds when a bride walks down the aisle I need to go to AF-C and then back to AF-S without all that side button/wheel/read the screen.
Now when in AF-C it does not matter if I have to hold a button to keep it in AF-C or press and re press to change back but in AF-S I need it all on the shutter button (focus and release) .
Clearly if I had U1 and U2 it would be no problem. I don't trust the menu on D810 as it cannot be locked.
Any thoughts ? everyone else has failed.....
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Using the AF-ON button with the camera set to AF-C one can press to focus and release to lock. Then one can take multiple shots without the AF system trying to be helpful. This gives much the same function as AF-S. To me it's AF speed and accuracy with manual focus logic. For tracking just press and hold the AF-ON button. A reflex can be formed is a short time. In a few days it should get very natural.
Perhaps someone else knows a fast way to switch between AF-S and AF-C but I doubt there is one. I've used this technique on the F5, D2H and currently with the D300s and D800. The eye never come away from the viewfinder. It works at the speed of a reflex.
Dave
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Back button focus does not do what I want.
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Back button focus does not do what I want.
As far as I know then you are out of luck. Maybe someone else knows a way to switch instantly from focusing on a static subject and then tracking a moving one that doesn't involve the AF-ON button.
Dave
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Back button focus does not do what I want.
From your opening text I was about to give you exactly the same advice David did. I´m working currently with a d700 and a d750 photographing a lot of people in movement that can present similar problems to be soved AF wise. It is working for me so...can you rephrase your needs?
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I don't mind pressing a button to change to AF-C or even hold one down but I don't want to be in back button focus mode (ie using two fingers) for normal AF-s work..............two fingers is ok for af-c (button and release) as I am only in that mode for about 60 seconds
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It seems the easiest way for you would be simply to switch to AF-C for those times you need it. Nikon used to have AF-S/AF-C/M choice with a single switch but at least for me it was often in the wrong position between the two modes. Today it requires two hands in practice.
I switched to AF-ON for focusing and always keep the focus in continuous mode now when I'm shooting (release+focus or was it the other way around). It means I do not have to switch between settings when photographing static and moving subjects. And with most AF-S lenses, manual focus is always available again without having to switch modes. One disadvantage is that focus priority mode is not available when working in this way (otherwise the camera would not fire if recomposing the main subject outside of the focus point). Another is that changing focus points manually would require interrupting the focus operation (unless using lens button to activate AF-ON). I find this to be the best compromise for me.
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Hasn't Nikon Solved that with the M/A AF option on certain (?, only tried it on my 1.4/58mm AFS) AFS lenses?
Admittedly I'm talking somewhat out of my league here as I don't use that option under real world conditions myself (only 'real' experience I have with it is that I once got a few good deals on AF D lenses as the previous owner absolutely wanted to upgarde to AFS lenses because of the M/A AF option) but it, as far as my experience goes, works flawless under 'laboratory' conditions
From what I've read (and as said found while playing around with this option), M/A AF allows to 'normally use a camera in AF-C mode, but if desired, make slight (manual) corrections using the focus ring on the lens (i.e. manually override the 'correct' focus setting found by the camera) to get a different point/plane in focus then what the camera has 'in focus'.
It would need a good eye/hand reflex, and good eye sight as well, but I can imagine to, while the bride is coming down the aisle, shoot with the camera in AF-C mode and lens in M/A mode, have the camera focus, and make slight manual adjustments when desired while shooting
May seem a little tricky with a bride walking down the aisle, but then I personally would never shoot a moving subject in AF-S mode anyway
I shoot a fair bit of catwalk, where the models basically similar to a bride down the aisle, walk down the catwalk towards the photographer, under, again similar to a bride, always under the best sort of lighting, and always shoot in AF-C mode (but don't use M/A focus)
E..g. these catwalk pictures http://www.pbase.com/paul_k/20160403_max_h_jhm were shot in the synagogue of the Jewish Historical Museum in Amsterdam. The 'aisle' the models I was shooting walked through, was so dark I could only resort to using flash to get a 'properly' exposed picture, so you can imagine how bad the light was for using AF (although my D800 passed with flying colors).
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don't shoot a moving object in AF-s ..I got that
You shoot catwalk in AF-C similar to aisle ..yes got that
So how do you switch fast from S to C and back to S.....that is the question....????
Seems a very simple request just to go from S to C without pushing 3 buttons and needing your glasses to read the display ...
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Perhaps I'm missing something here, but I'm wondering why it seems so difficult to use two fingers. I switched to BBF long ago, more or less for the same reason Pistnbroke cites, and find it works pretty well. There is an initial period when one forgets to do it right every time, but that's done pretty quickly. Now I hit the back button even when I'm borrowing other cameras, and have to remind myself not to. Once you're used to it, there's really little down side to this. About the only problem I know of is that in some cameras, such as the D3200, AFC is sometimes more forgiving than AFS. It's rarely a problem even so, and less so when a subject is not moving fast.
Of course I realize I'm in a peculiar position here using the lowly D3200, which lacks many useful features. BBF and shutter button AEL works very well on this camera, allowing you to spot meter, spot focus and recompose with complete control.
I would welcome a system as simple as "side button, wheel and read the screen," which my current D3200 lacks. I would have thought that after a little practice you would not have to read the screen. The wheel clicks. One right one left. What's to look at?
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I forgot my D300s has a three position switch. I haven't use the camera much lately. I do remember now I accidentally changed the position of that switch a few times and missed shots. I much prefer the current system. I'm sure others don't. I also forgot when shooting my D300s and thought I was shooting my friend's D300. Her camera is setup for AF-S on the shutter. I took one grip and grin and something didn't sound right. :) I switched my mind set to my camera and all went well.
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For those who need glasses for both distance and close viewing I have a pair of glasses that I initially setup for driving. They are of the transitions bifocal type. The bifocal is set low so they don't blur my forward vision while driving. I tilt the seat back as I have long arms and don't like the feeling that the steering wheel is in my throat.
For viewfinder use I look through the distance part of the lens and dial in a bit of minus diopter. The low set bifocal works perfectly for viewing the top and rear LCD(s). I can't use the camera with any skill without the bifocal. If I don't have those glasses I set the camera to "P" for professional and hope for the best. This is another set it and forget it if you will. Putting on and taking off reading glasses to see the LCD would be too cumbersome. If I didn't need glasses for distance I think I'd have a pair made with no correction for distance and the same correction for close-up. The only time I think about these glasses is when reading a book or my computer. I have to raise my head uncomfortably. Anyway I mention this as some here might find special "camera" or driving glasses helpful.
Dave
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don't shoot a moving object in AF-s ..I got that
You shoot catwalk in AF-C similar to aisle ..yes got that
So how do you switch fast from S to C and back to S.....that is the question....????
Let me reformulate it, as you obviously are missing the point :P
To begin
AF-S means (and I quote the Nikon/ Imaging Products site)
In single-servo AF (AF-S), focus will lock if the shutter-release button is kept pressed halfway after the camera focuses.....
Focus lock is used to change the composition without changing focus. If you frame the shot so that the main subject is in the selected focus point, focus, and then change the composition while keeping the shutter-release button pressed halfway to lock focus, you can create compositions in which the main subject is not in a focus point but is nevertheless in focus.
So when you use it on a moving subject, it will, when you half depress the shutter release, focus on the subject when it's in a certain spot, and have/keep the focus there (even if the subject has moved from that spot, and thus will risk to result in a out of focus picture) until either you take the picture, or take your finger from the release button, and refocus by half depressing it again.
Which for all practical purposes makes it the wrong choice for shooting moving subjects like brides walking down the aisle (or models down the catwalk)
I can imagine (although I never used it that way) that while using AF-C (where, again quoting Nikon/Imaging Products, 'the camera will continue to focus if the shutter-release button is kept pressed halfway after the camera focuses') you might want the focus on a different spot where the camera has it at that moment.
Again, for the reason mentioned earlier, very unpractical when your subject is moving, but perhaps an option one might want to use when the subject stops for a brief moment/spit second, and you want to 'fine tune' the focus for a specific spot (other then where the camera, based on the focus spot used, has it).
As changing the AF settings from AF-C to AF-S, is, as observed by the OP and others, too slow and cumbersome (and as all agree upon impossible to do so swiftly), rather then breaking one's brains over how to make that change fast nevertheless, in my opinion/'laboratory conditions' experience maybe better use the M/A focus settings on the (AFS) lens,while the camera is in AF-C mode.
The camera will, based om the AF focus point, focus on a certain spot within the composition.
But in that split moment the subject is standing still and when you want to focus spot on a different point in the composition (and where AF-S, and focus/recompose would seem the best option) rather use the focus ring on the lens to override the spot where the camera's AF (in AF-C mode) has locked in and adjust it manually to where you prefer it.
For all practice and purposes as slow as focus/recompose, (but that would not be a problem since the subject is standing still), but it will allow to get the focus on a certain, other then the camera has it in that composition, spot, without the hassle of changing from AF-C to AF-S.
It, I think, would/will mean having to have some skill with focusing very fast manually, and a quick eye/hand reaction to actually, in the split moment the subject is standing still, take the picture when the focus is on the desired spot.
And admittedly isn't as easy as using AF-S in focus priority (and just having the camera taking the picture when it thinks the picture is in focus, even if the subject may no longer be there).
Yes, not the 'answer' on 'how to how do you switch fast from S to C and back to S' , but from a practical point of view perhaps a viable option :)
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Seems a very simple request just to go from S to C without pushing 3 buttons and needing your glasses to read the display ...
Why is pressing the AF-mode button & rotating the rear main command dial one click not an option?
That is about as simple as it gets. You don't even need to remove your eye from the viewfinder to verify as it reads AFS or AFC in the viewfinder when the AF-mode button is pressed.
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Am I missing something?
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Why is pressing the AF-mode button & rotating the rear main command dial one click not an option
For myself I'd not want to chance miss setting the AF mode under pressure just before a critical shoot.
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I understand that Pistnbroke doesn't want to use the AF-ON button but for me a press and release of the AF-ON button in AF-C mode is functionally the same as AF-S.
Dave
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... for me a press and release of the AF-ON button in AF-C mode is functionally the same as AF-S.
Dave
Most AF "issues" can be avoided by learning how to use AF-ON efficiently in combination with AF-C. Concomitantly it is also the requested AF-S to AF-C quick change.
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Now don't lets all get confused with back button focus.
What I want to do with a D810 is this .
I usually shoot AF-S half press and then release .For about 20 seconds when a bride walks down the aisle I need to go to AF-C and then back to AF-S without all that side button/wheel/read the screen.
Now when in AF-C it does not matter if I have to hold a button to keep it in AF-C or press and re press to change back but in AF-S I need it all on the shutter button (focus and release) .
Clearly if I had U1 and U2 it would be no problem. I don't trust the menu on D810 as it cannot be locked.
Any thoughts ? everyone else has failed.....
I agree, for me it is also super annoying that selecting between s and c is a 'one bottom and one wheel click' (two fingers, one on each hand and both at the body of the camera) job - when it used to be just one switch one finger on one hand.
This was one of the main reasons to stay with D3 and D3X! Not upgrading to D4 when it came out!
AF on - Button - Is not the same thing at all! I know some people think it is 'the way' but not for me.
The nice image in the user manual posted here is nice - But in reality the values are this size in the display; s c
Not very user friendly! For fast paced work.
I'm confident Nikon will change this in new/future cameras - but unfortunately that is the current configuration....
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I've gone back to AF-S with the AF-ON button several times over the years and I always quit shortly feeling my AF was more accurate with AF-C and the AF-ON button for static subject. AF-C with the AF-ON button for both static and moving object works for me. I don't have to think about changing the mode ever. My thumb can easily move to the AE-L/AF-L button which I map for FV Lock (Flash Value) for run and gun. The thumb knows what to do and when to do it.
I'm left eyed and my thumb rests on the bridge of my nose and on the AF-ON Button. I press the camera moderately into my face for stability. I wear glasses of the transitions bifocal type with the bifocal set low for driving a car. There is just enough bifocal to use the top and back LCD(s), no need to fumble with glasses. The only problem is I need to clean my glasses occasionally. Without these glasses I may as well to set the camera to "P" for professional and hope for the best. :)
Dave
Another advantage for me is it's really natural to switch from auto focus lenses to manual focus. The first thing I do with a new camera is get the AF off of the shutter release button.
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Part of the issue with AF-ON in AFC mode (the most useful) is that with static subjects you need to be sure that focus has settled down to the correct setting.
This is a bit of a problem with mirrorless, as AFC (which is what makes the AF-ON button worthwhile) tends to hunt, because of contrast AF. I hope the X-T2 will address this issue.
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Part of the issue with AF-ON in AFC mode (the most useful) is that with static subjects you need to be sure that focus has settled down to the correct setting.
But what happens with AF-S? It locks but did it lock prematurely? If it did then the focus may be off enough to waste the shot. I'm speaking here of a Nikon with phase detection AF with release priority. I can't abide with focus priority except for focus trapping.
Notice that some lenses focus faster than others and this certainly appears to be tailored to the use of the lens. Many note that the Nikon AF-S 70-200/2.8(s) focus faster than the AF-S 85/1.4(s) and the new AF-S 105mm f/1.4E ED. This appears to me to be a feature of the f/1.4 lenses as they need more accurate AF while the 70-200/2.8 are often used for sports where they need to focus quickly and need to track fast moving subjects.
At the end of the day nothing is perfect.
Dave
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At the end of the day nothing is perfect.
Dave
Yes!
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Part of the issue with AF-ON in AFC mode (the most useful) is that with static subjects you need to be sure that focus has settled down to the correct setting.
This is a bit of a problem with mirrorless, as AFC (which is what makes the AF-ON button worthwhile) tends to hunt, because of contrast AF. I hope the X-T2 will address this issue.
I have never found this to occur with the D3200, and there seems to be no measurable difference between the results when using BBF with either mode.
It's always a little frustrating since Nikon does not tell us everything and only hints at it. We are told that in AFC the auto focus is more forgiving, without really letting us know whether this means that the actual AF is sloppier or just the focus priority less rigorous. A quick and unscientific test suggests that with BBF there's no measurable difference between the two on a static subject.
In any case, though, I've been using BBF for some time, and have never found it to hunt in AFC. It's impossible to test how it might behave in Live View because BBF does not work at all with continuous focus (AFF in LV) anyway.
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But what happens with AF-S? It locks but did it lock prematurely? If it did then the focus may be off enough to waste the shot. I'm speaking here of a Nikon with phase detection AF with release priority. I can't abide with focus priority except for focus trapping.
Notice that some lenses focus faster than others and this certainly appears to be tailored to the use of the lens. Many note that the Nikon AF-S 70-200/2.8(s) focus faster than the AF-S 85/1.4(s) and the new AF-S 105mm f/1.4E ED. This appears to me to be a feature of the f/1.4 lenses as they need more accurate AF while the 70-200/2.8 are often used for sports where they need to focus quickly and need to track fast moving subjects.
At the end of the day nothing is perfect.
Dave
AF-S mode predicts and acquires precise focus by design.
AFS 1.4 lenses has less fast AF as to ensure and acquires precise focus by design.
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The purpose of AF-S mode is that the camera focuses until it decides it has acquired focus, then stops and you can do your recomposing which was the default way of doing things in the early years of AF when there was only a single point (or the peripheral points were not so sensitive). By default, AF-S mode is associated with focus priority. I guess when you combine AF-S mode with release priority, you should be able to interrupt the process of focusing by taking a shot before the camera has finished acquiring focus. I have never tried this combination of settings though.
I stopped using AF-S mode when I had the D70 and the resulting focus accuracy was poor. The camera would often decide it was in focus when it was not. In AF-C mode with AF-ON, I could wait until I could see the subject in focus and take a few shots, and the result was clearly better. In more advanced cameras AF-S worked much more reliably at that time, but I wanted to operate all my cameras in the same way, so I started using AF-ON with AF-C and release+focus priority (release priority if release+focus is not supported). This has worked well as I don't have to change settings if the subject is static vs. moving, and release+focus priority waits a little bit between shots to acquire focus before releasing, but does not interfere with focus + recompose if the subject is still, I can still use that to achieve more off-centered compositions. I monitor the sharpness in the viewfinder and take what I see into account in timing my shots. I'm aware that for static subjects AF-S with focus priority would probably give a higher percentage of focus keepers but I don't like the fact that the camera decides when focus has been achieved - I want to decide when the shot is taken, and I base that decision on what I see in the viewfinder. The timing may be slightly delayed by the camera if it wants to keep focusing a bit but this has not prevented me from timing shots based on focus and subject expression.
The bride (or bride and groom) walking on the aisle before and after the wedding ceremony can be one of the most difficult subjects to photograph. This is because the corridor has often poor lighting and behind the subject there can be bright light and structures (church altar, wall texture etc., or the outer door) which are attractive to the AF systems rather than dark faces in the center of the picture. ;) In particular the church I was at last time had brightly lit wall behind the altar and there was complicated texture in it (it is a medieval church). I think the safest place for the focus point in this circumstance would be to point it at the middle of the body (as then the wall carvings would not be near the active AF point, also center points are the most reliable in focusing), but I have a habit of placing the focus point on the face so that focus is accurate even when using fast lenses (f/1.4, f/2). In the corridor shots I typically use the 24-70 because it can accommodate different framings in a fast changing situation and focuses quickly. As usual my camera is in release+focus priority and I press AF-ON to keep focusing while I take the shots. Typically I get maybe one third of slight focus misses in this situation because there is not enough light and contrasty detail in the bride's face vs. bright textured wall in the background. Also the light level can be very low, ISO 6400 is not enough to get correctly exposed blur-free shots, and I've resorted to 12800. With the D810 this looks so-so, but with the D5 the results look ok even in colour.
Flash is another option for this situation. A flash unit typically has a built in focusing assist light but that only works (if I'm not mistaken), in AF-S mode with center point AF. I have read it being recommended that the aisle shots be made using the support of the focus assist light but of course then there is the problem that the bride (or bride and groom) may be moving more quickly than would be ideal for photography. ;) I am staying with the AF-C + AF-ON method but am considering moving my focus point to the center row in order to avoid distraction by the highlighted textures in the background. I suppose I could try the focus assist light method at some point. I just don't like the idea of having to switch to single servo focusing especially when the subject is moving. Incidentally the recommendation I've read for this situation also includes use of the flash itself to light the main subjects, but I tend to go with available light. It can be debated whether the flash fits in this situation (it would help reduce movement blur on the front side of the subjects, but a point light source adds sharp reflections and emphasizes skin pores which I don't like). I guess the available light can be regarded to be of poor quality as well, so it is a choice out of two not so great options. Anyway, I wanted to mention this because if the OP prefers to work in AF-S mode (shutter button activated AF), perhaps single servo focusing with focus assist light from a speedlight would work acceptably. I guess the key is how much depth of field you have, and how quickly the bride (or bride and groom) are walking. ::)
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Quote from Nikon:
However, maintaining focus doesn't guarantee a sharp image, as there is a short time lag between the release of the shutter and the capture of the picture. To solve this problem, the focus tracking system is a predictive system that uses special algorithms to forecast the position of the subject at the moment the image is captured. The prediction is based on a measurement of the subject's movement and speed
As far as I have experienced this is the case for both AF-C and AF-S mode.
And I know it is the case also for the lens itself, the CPU in the lens tell the camera where to stop the focusing motor for best stopping/decelerating the motion of the actual focusing elements for that particular lens, it's build into the calibration of each lens after a run on the test stand where the lens is set to try several runs, too far - too close, to obtain best focus, from both directions.
The camera in AF-S
Push focus button;
The AF sensor picks up the brides motion and see if she is approaching or leaving and her speed and distance to her.
The camera AF sensor also picks up that the lens is either focused too far or too close and by how much.
Camera calculates where will the bride be when the lens finish focusing and then predicts when to open the mirror and fire the first curtain,,,
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Erik, I would really be surprised if this Nikon quote also applies to AF-S, I think it is AF-C only.
In single-servo AF (AF-S), focus will lock if the shutter-release button is kept pressed halfway and no focus tracking is happening.
And in my experience with even the slightest movement AF-S will off.
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The camera is predicting where the target will be in AF-S
The camera is tracking and predicting where the target will be in AF-C
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With AF-S there is no predicting and to me there also should not be, it should be static.
Your quote is coming from the Nikon site on 3D Focus Tracking
http://www.nikonusa.com/en/learn-and-explore/article/ftlzi4lx/3d-focus-tracking.html (http://www.nikonusa.com/en/learn-and-explore/article/ftlzi4lx/3d-focus-tracking.html)
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Yes it is taken from the 3D.
But AF-S would miss the target if it didn't predict in the same way when the actual exposure will occur.
Imagine a race car full speed, how would the exposure be at the correct moment when the target enters the focus plane if there was no prediction done in camera,,, just like AF-C need prediction on top of traction to nail it.
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Erik, that is indeed my experience that AF-S will miss the target with the slightest movement of the object between half press and actual exposure.
But probably good to have some others step in this discussion to resolve it.
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I would guess that there can only be prediction in AF-S if the shutter release is fully depressed, since that is when the camera has full control over when to shoot the picture and therefore it can put the focus where the subject is predicted to be at that time. But with standard usage of AF-S the photographer can wait an undetermined amount of time after half-pressing and before he/she presses the shutter release, so I don't see any way to accurately predict where to put the focus other than where the subject was measured in the first place.
Please consider that I'm just speculating since I don't know how Nikon's algorithms are set up.
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I have only read of predictive focusing as a function of AFC, and have difficulty imagining how it could work in AFS, and why one would want it at all. Since AFS allows the user to choose a focus point that will not change when you recompose, and that need not fall within any of the designated focusing areas, or for that matter even in the final frame, how would the camera track it, and would it not defeat the purpose to have the camera second guess your choice?
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You misunderstand.
You should not just half press and wait in AF-S,,, that is not the point.
You push the shutter all the way when you want the image,,,
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You misunderstand.
You should not just half press and wait in AF-S,,, that is not the point.
You push the shutter all the way when you want the image,,,
I wonder if there is a communication issue here. If you focus and recompose in AFS, and are not using the back button, then you must half press and wait at least for as long as it takes to settle on a composition. I would expect when doing this that the focus point would remain exactly where I initially put it, and would be unpleasantly surprised if the camera tried to guess my intentions, and otherwise surprised if it were able to do so when my initial focus point falls outside the camera's chosen focus areas. If one could not do this, what would be the point of having AFS at all?
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I would guess that there can only be prediction in AF-S if the shutter release is fully depressed,,,,
Yes exactly!
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I find AF-S almost useless for taking a photo of a moving object. The camera may estimate the distance the subject will travel before the shot is taken if the shutter release is fully depress at the outset. In that case the camera determines when the shutter is release. AF-S can be used for "manually trapping" the subject as one might do with a manual focus camera: F, F2, F3 but there is no advantage over AF-C and the AF-ON Button. AF-S for a moving subject precludes shooting a burst as only the first shot will be in focus. My cameras are always set to continuous advance and the low advance speed is bumped to five or six frames per second is available. I normally squeeze off single frames.
I honestly don't see any reason to photograph a moving subject if AF-S mode other than that the way the camera is set and there is no time to change to mode to AF-C. This is where AF-C and the AF-ON button allows one to switch from "AF-S" like use to AF-C at the speed of reflex, even faster than conscious decision. There is no way to switch from AF-S to AFC mode that as fast. There is no way to switch that is as error free.
Yesterday I was photographing my friend's cockatoo. The bird will stand in the same place sometimes for several minutes but it's not standing still. It will shift it weight from foot to foot and move it's head. It's motions are such that a 105mm lens at f/5.6 doesn't have enough DoF to cover for this motion. Not only that but the space I'm photographing the bird in is built like an orchid house so light levels are reduced. The subject distance is generally about 1.5m. Shutter speeds are frequently between 1/250 and if lucky 1/500. The object is always to get an eye in focus. The decision of when to lock focus can't be left up to the camera. AF-S mode is next to useless. The camera can not possibly predict this kind of erratic and punctuated motion. I'm actually able to get some photos in focus with a 105/2.8 AIS Micro-Nikkor under these condition but the AF-S 105/2.8G ED Micro-Nikkor has sharply increased the number of in focus shots close to 50%. Then there is loss though subject motion. Many focus attempts do not result in a shutter release as I know the bird has moved and will be out of focus. I hope this is keeping my reflexes sharp as I have little time for photography other than my bird sitting. It helps that the bird likes me and calls me by name, "Hi David." Unfortunately my friend won't allow me to photo photographs of her bird on the internet.
Some thoughts on Focus Priority. When the original Minolta Maxxum came to Los Angeles a camera salesman friend called me and told me the Maxxum was in. When I got a chance with the camera I picked a subject. The camera focus on it but since it only offered focus priority it would not let me take a photo. I knew the camera had focus correctly but the camera didn't. I didn't even have to recompose to mess up the camera. For most use I find focus priority useless. Trap focus comes to mind but nothing else.
I've typed too much so it's time I just sit back and read.
Dave
Sorry about the typos as I'm out of time.
I'm glad there are modes that satisfy others even when I don't use them. It's good when a camera can be adapted to many different ways of using it.
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I wonder if there is a communication issue here. If you focus and recompose in AFS, and are not using the back button, then you must half press and wait at least for as long as it takes to settle on a composition. I would expect when doing this that the focus point would remain exactly where I initially put it, and would be unpleasantly surprised if the camera tried to guess my intentions, and otherwise surprised if it were able to do so when my initial focus point falls outside the camera's chosen focus areas. If one could not do this, what would be the point of having AFS at all?
Well, I really did my best but I didn't find any mentioning on the several Nikon tech sites of predictive AF possible with AF-S
In this article http://www.nikon.com/about/technology/rd/core/software/caf/index.htm , it is only mentioned in combination with AF-C, just like in this article http://www.nikonusa.com/en/learn-and-explore/article/ftlzi4pn/51-point-autofocus-system.html#@/en/learn-and-explore/article/ftlzi4po/af-area-modes.html it's mentioned as only possible when using multiple AF points
That also is accordingly mentioned in this article (although it talks about 3D focus tracking) http://www.nikonusa.com/en/Learn-And-Explore/Article/ftlzi4lx/3D-Focus-Tracking.html#@/en/learn-and-explore/article/ftlzi4lx/3d-focus-tracking.html the AF system must accumulate subject location data using multiple focus areas
So it seems to be physically impossible to have AF tracking/predictive focusing (or however you might want to call the option of the camera focusing on a subject on a spot other then where it actually is in that moment, in anticipation on where it's expected to be the next moment) in AF-S.
Simply because you then only use one AF point, which, at the moment the release button is pushed in halfway, is busy achieving a 'sharp picture' at the spot where the one AF point is aimed at, and there simply are no other AF point available to calculate where the subject is expected to be the next moment.
This (only one AF point active when using AF-S mode) is also stated in this article (not an official Nikon site, but a Nikon user site) https://blog.nikonians.org/digitaldarrell/2011/08/dd-understanding-nikons-autofocus-af-area-and-release-modes.html
Or I'm a misreading the articles mentioned?
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Well, I really did my best but I didn't find any mentioning on the several Nikon tech sites of predictive AF possible with AF-S
In this article http://www.nikon.com/about/technology/rd/core/software/caf/index.htm , it is only mentioned in combination with AF-C, just like in this article http://www.nikonusa.com/en/learn-and-explore/article/ftlzi4pn/51-point-autofocus-system.html#@/en/learn-and-explore/article/ftlzi4po/af-area-modes.html it's mentioned as only possible when using multiple AF points
That also is accordingly mentioned in this article (although it talks about 3D focus tracking) http://www.nikonusa.com/en/Learn-And-Explore/Article/ftlzi4lx/3D-Focus-Tracking.html#@/en/learn-and-explore/article/ftlzi4lx/3d-focus-tracking.html the AF system must accumulate subject location data using multiple focus areas
So it seems to be physically impossible to have AF tracking/predictive focusing (or however you might want to call the option of the camera focusing on a subject on a spot other then where it actually is in that moment, in anticipation on where it's expected to be the next moment) in AF-S.
Simply because you then only use one AF point, which, at the moment the release button is pushed in halfway, is busy achieving a 'sharp picture' at the spot where the one AF point is aimed at, and there simply are no other AF point available to calculate where the subject is expected to be the next moment.
This (only one AF point active when using AF-S mode) is also stated in this article (not an official Nikon site, but a Nikon user site) https://blog.nikonians.org/digitaldarrell/2011/08/dd-understanding-nikons-autofocus-af-area-and-release-modes.html
Or I'm a misreading the articles mentioned?
No, I believe you are reading the articles right with one small exception. As far as I know, there is no attempt to make AFS anything more than single one-shot focusing without prediction or adjustment after the initial hit.
The small exception is that, on some cameras at least, it is possible to combine AFS with multi-area focus mode, in which the camera's processor chooses the focus point or points. However, in AFS this is still a single-shot event, and once focus is achieved, it does not change again.
e.t.a. for example, on the D3200, in AFS one can choose between single point and MA modes, but cannot choose dynamic area or 3D.
In AFC mode, the camera does not seem able to distinguish between camera movement and subject movement, which is why one cannot focus and recompose in AFC. I would assume that this is the case in AFS as well, and thus, it would be impossible to allow for adjustment to a moving subject without disabling the ability to recompose.
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I'm not preaching anyone to use AF-S mode for moving objects. You are free to do what ever you like ;)
BTW: Again I'm not stating there is any tracking going on in AF-S!
I switch between the two modes all the time and really like them both and find that they both are working amazingly good.
I have almost no out of focus images for AF-S mode for moving subjects,,,
Yes if I half press and hesitate to fully press then I get an unsharp image if DOF is shallow, but that is misusing the AF-S mode,,, in that case I switch to AF-C or the AF-On
BTW I'm referring to F4, F5, D1, D1X, D2X, D3, D3X and D810 it has just gotten better and better ;)
Lenses - Prediction:
Below is a description for inspection and adjustment of an AF lens focusing system:
In both cases, AF-S or C the camera use the information from the CPU about 'prediction' of how to drive the AF motor of the particular lens in use to reach the right focus plane at the right time, to achieve a sharp image.
Here is the Nikon Service manual for 24-70mm AFS 2.8:
http://allphotolenses.com/public/files/pdfs/4b4fb97547c5d54819491c07c715f2c2.pdf
On page 70 and forward you see how to inspect and adjust a lens CPU AF values.
On page 76-79 it is described how the 'predictive' part of the lens focusing, overrun/underun is measured and adjusted.
This show that the camera is also predicting or taking an educated guess, from the values given by the lens CPU how to run the AF engine inside the lens so it stops focusing at the right point in time.
The camera is not just picking up the movement and position of the object with the AF sensors in AF-C or AF-S mode and just fire the shutter, it would miss the focus point.
PS no Bjørn cant program this into your CPU for you Manual Focus lenses,,,
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Erik, you know much more about lens technology than probably anybody on this forum but this technical manual does not convince me that in AF-S mode prediction is happening. The overrun/underrun part is on on the lens acquiring focus quickly in back-and forth driving to get to the final position and does not cover prediction.
I would only "push through" without checking focus acquisition in "emergency situations". Normal operation for me in AF-S is to half press to confirm focus and then without hesitation :-) push to actual exposure.
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BTW I'm referring to F4, F5, D1, D1X, D2X, D3, D3X and D810 it has just gotten better and better ;)
That I fully agree with
My first AF body was the F801 (skipping the F501 was intentional, the AF on that body really was slow), and upgraded with each new AF body that came after it (F801S, F90, F90X), simply because for what I shot (catwalk and fashion on location) I really needed a faster AF (although that didn't stop me from still shooting catwalk with a 4.5/300mm ED, manual focus, or location shoots with a 500mm mirror reflex)
In my experience up to, and including the F100, dynamic AF wasn't 100% reliable (went flat on my face with a shoot when I relied on it with the F100, never liked that camera since ;) )
Fortunately it became near foolproof on the D1 and upwards, and I don't hesitate to use it nowadays (though never 3D AF nor Auto Area AF)
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Erik, you know much more about lens technology than probably anybody on this forum but this technical manual does not convince me that in AF-S mode prediction is happening.
If the camera is set to AF-S/focus priority and the photographer fully presses the shutter button to take a picture there is a very small lapse in time between the moment the camera acquires focus and the moment the image is recorded. Compensating for that lapse in time, however small it might be, is what I believe Erik is speaking of and it seems reasonable to think that it would be programmed that way seeings how the technology is already there.
Seems a few tests on fast moving subjects could verify this.
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Erik, you know much more about lens technology than probably anybody on this forum but this technical manual does not convince me that in AF-S mode prediction is happening. The overrun/underrun part is on on the lens acquiring focus quickly in back-and forth driving to get to the final position and does not cover prediction.
I would only "push through" without checking focus acquisition in "emergency situations". Normal operation for me in AF-S is to half press to confirm focus and then without hesitation :-) push to actual exposure.
Without being able to peek into the code of the AF system, some sort of prediction (in the sense of estimation) is needed to deal with the data coming from the AF sensors, which is incomplete and noisy.
When the AF sensor picks up a signal, that is not an exact measurement as there is uncertainty about where exactly the subject is. Movement of the subject increases uncertainty about its position, but also means that any delay in the shutter release will change the position. Therefore, I presume, it would have been impossible to get this system to work reliably without incorporating prediction also in AF-S mode. If you half press in AF-S with a moving subject, the system will inevitably fail.
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Full pressing in AF-S mode without checking focus acquisition will result in a high number of failures in my experience and therefore I consider it a bad practice only to be used in emergencies.
To me movement prediction should not be part of the AF-S algorithm and I have not seen any convincing evidence in this thread that it actually is, but I will rest my case.
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Arend, I would not use AF-S the way you describe it.
I regard Marianne Oelund as one who has the a huge amount of knowledge about Nikon AF and AF sensors.
Anyway this is her statement cut out of a long series regarding AF sensor modules
https://www.dpreview.com/forums/post/54762863 and https://www.dpreview.com/forums/post/54211961
Keep in mind that Nikon state that even in Single AF mode, the camera is supposed to be able to detect subject movement, which requires continuing to monitor the AF sensor data until focus is locked.
And:
The AF system designer cannot assume that the subject is stationary in any case. The only way to ensure the lens is moving toward correct focus, allowing for a moving subject, is to recompute focus error as the lens slews. Even in Single AF mode, Nikon claim the system will detect subject motion.
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Thanks Erik for the references, will have a look at them later !
(and then it will take me even more time to digest having quickly looked at the second link :o)
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Second link is actually very interesting where Marianne clearly show the AF module design and reverse engineer it; She shows why there is no difference in AF performance between a f/1.4 and a f/5.6 lens,,, and the AF f/5.6 and F/8 restrictions Nikon always states are clearly unveiled, they are simply dimensional restrictions of the AF module itself!
A very good read for the technically inclined ;)
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I find that f/2.8 lenses in general autofocus much better than f/5.6 lenses. On the D5, f/5.6 only give a handful of cross type points, and on some f/4 lenses there is also a restricted list of cross type AF points available (as well as a few f/2.8 lenses). f/2.8 lenses typically autofocus more reliably than lenses of other maximum apertures, I would say empirically that the AF system behaves as if it were optimized for f/2.8 lenses. I haven't studied the theory of it though, it is just practical observation. I have a few individual lenses (such as the 20/1.8 ) which are faster and autofocus better than f/2.8 lenses (the 14-24/2.8 ) but in most cases going from f/2.8 to f/2 and f/1.4 is with a lot of pain and fine tuning. Thankfully Nikon has automated that in the latest two high end DSLRs, so at least a starting point value can be reached easily, even if it has to be verified and sometimes adjusted based on real world use.
My experience is that AF-S cannot be trusted so many years ago I stopped using it completely (apart for some testing situations), but cameras have improved since and perhaps this goes for AF-S mode as well. But I remain an AF-C user and prefer it. I cannot stand the camera deciding when to stop focusing; it's my call to make.
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I have good results with my D800 in AF-C + AF button
If I'm using big apertures, I rather move the focus point to the correct spot , vs focus and recompose as I often will not get the right focus
I do not use AF-S
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I find that f/2.8 lenses in general autofocus much better than f/5.6 lenses........
Well I have always had the same feeling, but for sure the series of 2.8 lenses are generally of a very high standard and has the best AF-motors build in.
But none the less the way the AF moduel is designed it treats all lenses below f/5.6 the exactly the same, it is not the case that 'more light' enters the AF module from a f/1.4 lens than a f/5.6 lens - Simple as that.
Actually the aberrations of found in fast glass on the faster 1.4 lenses makes the focusing harder for the AF module,,,
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But none the less the way the AF moduel is designed it treats all lenses below f/5.6 the exactly the same, it is not the case that 'more light' enters the AF module from a f/1.4 lens than a f/5.6 lens - Simple as that.
If the AF module limited in the same way an R screen for an F2 or F3 is limited in its accuracy because of the angle it can see through a slower f/3.5~5.6 lens? Are some of the segments of the AF module looking at the lens barrel on an f/5.6 lens so they cannot contribute to focus?
Dave
This is probably an ignorant question as I've never read much on how the AF modules function optically.
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Multi CAM 20k has restrictions on f/5.6, select f/4 and at least one f/2.8 lens (60 Micro, possibly because it becomes slower at close focus) as to which of the 99 cross type sensors function as cross type so this seems similar to Canon's earlier models where cross type or double cross type is only available on f/2.8 or faster lenses. The details are in the D5 manual.
Anyway it is clear that in practice f/2.8 lenses AF better than f/5.6; whatever the technical reason may be. There must be an explanation even if it has nothing to do with the quantity of light the AF sensor sees.
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Please just follow the second link for further information - Thanks ;)
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I like to see a NG-workshop on AF technicals and techniques in the future of NG, held by someone who really knows what he/she is talking about like Ilkka
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I'm curious: has the OP's question been answered?
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Yes it has, and answer is: No I can't.
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I ask because reply #13 looks like the right answer to the question, but the OP has never said that he is satisfied with this answer.
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I like to see a NG-workshop on AF technicals and techniques in the future of NG, held by someone who really knows what he/she is talking about like Ilkka
Ulp, I wonder about the last part. ::)
A focusing workshop could actually be interesting. It could cover topics such as
- general theory of focusing, AF, MF, different camera features including pattern recognition
- autofocus from a wildlife photographer's perspective (volunteers?)
- autofocus in people photography (sports, weddings, portraits etc.)
- fine tuning / microadjustment of autofocus in DSLRs
Another day could focus on
- manual focusing using OVF, EVF, LV
- techniques to extend near-to-far sharpness: focus stacking and tilt
- focus in UV and IR photography (?)
- creative use of focusing and shallow depth of field
The location should be such that stuff is happening and AF use can be practiced on a variety of subjects. The manual focus section could be at a landscape location or e.g. garden or forest, a location which is conductive to a slow photography approach. :)
Sports events can be problematic in that often photography is restricted by the organizers. Also for the sake of creativity it would be nice that people can move about to find their own subject and vantage point.
I think outdoor festivals such as carnivals, or other types of festivities can be excellent subjects where AF can be used and public photography is common and welcomed by the subjects / performers in general.
However, the "slow photography" (i.e. practice of manual focusing, focus stacking, creative focusing) part would likely have to be a totally different location.
I'm always keen on exploring new locations and events.
Anyway just my thoughts on the topic.
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Sound interesting Ilkka, I will sign up (depending on timing and locations) !
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I was just expressing thoughts, not that I would organize it ;-) But maybe someone can. I think nikongear members would be able to give excellent specialist talks on some of these topics. Also I think that it would be great for sharing ideas.
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Sorry folks not to reply but been photographing birds in the Somme Estuary in France for a week....
All very interesting stuff and I will do some more testing ....I have on occasion forgotten to move back to AF-s once the bride was at the altar and not had a problem unless you get a group where you focus ..re compose and the focus point sits on the trees behind the group ( I call it a shoot through)
Maybe I should be in AF-C as this works 99% of the time on static shots and push the af on if there is a problem.
Unfortunately a wedding is not the best place to experiment....
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I never leave AF-C; I even deselected AF-S. For the wedding picture, simply stop to push the AF-On rear button and reframe.
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I am sure many of you have taken on degree style projects where the solution is the opposite of what you originally thought.
The conclusion I came to is that its worth giving the AF-C option as explained above a try ... after all guests arriving are walking towards me ..the car arriving is moving towards me etc. etc. and on some occasions I have left it on AF=C in error only wondering where the bleep had gone ! On the D7100 the af-on button is too close and my thumb nail hits my nose but on the D810 it seems ok .Have a simple wedding ( ??) this sunday so will give it a go .
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Pistnbroke, I still wonder why the button+dial method does not work. It only takes 1sec to change from AF-C to AF-S. Of course, the back button AF with AF-C is what I use and recommend, but it does not work for everyone.