90% of the time I have found it to be my, i.e. user, error
Only 90%!? For me it's closer to 98% I reckon
90% of the time I have found it to be my, i.e. user, error
It's been documented that Nikon's 153 point AF system does sometimes focus on the background rather than the subject in certain scenarios. I first saw it mentioned on the D5 (was it @sk66 that mentioned it?)) and I too had it happen to me on the D850. It looks like it's happened here too. My experience was when there was a busy background and the subject was small in the frame.
It's been documented that Nikon's 153 point AF system does sometimes focus on the background rather than the subject in certain scenarios. I first saw it mentioned on the D5 (was it @sk66 that mentioned it?)) and I too had it happen to me on the D850. It looks like it's happened here too. My experience was when there was a busy background and the subject was small in the frame.
Less of an issue with that, but I think I had the odd one that did it with single point.spot (single) cell focus?
TBH it can happen with most cameras, I think it's more prone with the Nikon 153 point system for some reason. I wish I could find that thread as I can't remember why. I know the OP was in conversation with Nikon for quite a while about it, but I can't remember what the outcome was.I have had this happen on both Nikon and canon - I put it down to my poor technique.
The outcome from Nikon was "it's as designed."Less of an issue with that, but I think I had the odd one that did it with single point.
TBH it can happen with most cameras, I think it's more prone with the Nikon 153 point system for some reason. I wish I could find that thread as I can't remember why. I know the OP was in conversation with Nikon for quite a while about it, but I can't remember what the outcome was.
So I was right, it was you that posted about the problem Thanks for posting again, sorry I couldn't find the original thread. Interesting that the dynamic mode doesn't necessarily select the chosen focus point when acquiring and tracking focus, that's useful info. I thought that the AF lock on wasn't as sticky in my D850 as it was on my D750 but thought it must've just been my imagination so thanks for clarifying that it's not just me So I guess the only mode that's close to guaranteeing it's going to AF on your subject and not the background or whatever is single point? TBH that's what I've find with any camera I've used. I've tried 3D, group, dynamic, (plus the different Sony modes such as flexible spot when I had that) and always revert back to single point as I find it the most accurate and consistent. Fortunately for me I rarely shoot BIF so don't need group etcThe outcome from Nikon was "it's as designed."
With the 153pt AF system in a dynamic mode it releases tracking much sooner and it doesn't function in a "nearest" manner anymore. The "blocked shot delay" is really just a "refocus delay," and it will happily select stuff farther away when it times out. The only slight exception is group mode which does *kind of* perform with a "nearest priority."
Also worth noting is that both the 51pt and 153pt systems are *not* using only the selected point to acquire focus when in a dynamic mode (maybe any mode, I haven't actually tested). It is also using all of the focus points immediately around the selected point... if the selected point fails to find a good focus it will lock on using the surrounding points if it can.
The PDAF system of a DSLR is using the position (phase) of very tiny images to determine focus... it cannot see/resolve very small details in the scene (it functions very much like a split screen viewfinder does).
You are expecting too much, and there are some user error/understanding issues as well I think.
By default, if you are using back button focus Nikons do not really care if the subject is in focus when using a dynamic mode, regardless of the release priority setting (it only cares for the very first initial acquisition).
The distance is too great. As others noted the atmospheric conditions will affect things... it can be heat, moisture, dust, etc, but there is always some crap in the air. Nothing makes as much of a difference as getting closer does, it helps reduce the atmospheric issue, and it makes the details larger so the PDAF system can actually see/resolve them.
Distance also affects SS requirements. If the subject is in motion then you need a higher SS when it is closer. But you also need a much higher SS when the subject is more distant regardless of it's speed. As an example, put your finger over something fairly large and relatively close; something like a chair across the room. Now move your finger around... how far does it have to move before it's not over the chair any more? Now put your finger over something about the same size about 100ft away... how far does it have to move now? That's exactly the same thing that occurs when trying to keep "pixel on detail" to prevent recording motion blur. And that image movement is also affecting the tiny images the PDAF sensor is trying to use.
If Gil sends me the RAW I will check her images, (it's raining today here in sunny SW France and I'm doing very little!!) - she should do this before considering fine tuning the lens, (a Nikon zoom!!), which using FoCal or whatever takes some skill, can be very time consuming and needs good consistant light to perfect - (I went off FoCal and now would always use the Spyder Lens cal manual system - which I may then just check with FoCal, but I have found that FoCal can give simply inaccurate readings, but maybe that's user error!!).
Heat Haze, etc., etc., - we always look for excuses when are images our not sharpe or OOF - but 90% of the time I have found it to be my, i.e. user, error
Back home soon, will send over the RAWs, and some samples with my other lens where AF didn't work out for me at the wedding. With the way things are going, it does look like the failure is down to user error rather than faulty equipment!! Blush.
P.S. I'm a guy
P.S. I'm a guy
Here are the original RAWs for the images posted above as well as a few extras. I haven't yet tried to download and install the AF software suggested. @BillN_33, maybe you could take a look if you have time
https://drive.google.com/open?id=1PuQawjNrSBgIpJzwgwdPbcpnixFMeyiA
sorry about that - I did not know if you were "Gil" or "Bev" - sometimes difficult on these forums - maybe I should use OP.
What I think many people do not realise is that (if you do not practice your technique) the camera (and therefore the focus point) will move when you press the trigger, it's always been like that, but even more so with a SLR - just try it - using the focus point plug in software - focus on a bird - press the trigger then look at your images - when you took the shot you were convinced that you had hit the birds eye - then look at the results in LR - you will be surprised how many times you missed the birds eye, (birds move even when they are still!!!) - but the user moves as does the camera when you press the shutter.
You can try, LV, Mu and remote - but by the time you have set that up the bird has probably gone!!
Give it a go now, I don't think the settings were correct initially to allow everybody access.
IMO, all of these shots are too far away, especially given the atmospheric conditions and shooting over water, to give ideal satisfactory results.
You say that your rig isn't very stable, so you would need very good long lens technique and I would be inclined to raise the SS to a minimum of 1/2000
Admittedly today - my subjects were rather far away, however I would have expected to see sharp results at 100%? I know with the D850 (a much more expensive camera I know) I've heard you can achieve pretty sharp results even at 200%, and even 300% with a prime
And just to prove this point. Here's a shot with the D850 and then a 1:1 crop. Whilst not too bad, it's not stellar either. Usable though imo.You may have heard this but I've seen absolutely no evidence of any shots being posted that are sharp at 100% crop, never mind 200%/300%
Looking at the the images sent one of the main problems is (too low) shutter speed and movement, (by the subject and probably camera movement)
all shots are at low ISO's and most at 1/800th sec
as Wez says use much high shutters speeds and push the ISO higher to get shots that have less "blur"
Practice long lens technique and then lower shutters speeds will be possible
all shots seem to have been taken at the same distance, but strangely enough the image with no focus point info is the only one that is half decent - apparently Gil use manual focus for this image!
and on many occasions you just can't get close enough - particularly when there is no cover without interrupting that behaviour you want to record. I'd like to be able to have the skill to take good pictures both distant, albeit not as detailed as well as the more pleasing photos when you do get the opportunity to get close enough, or be close enough. I also find myself in the position of being far away from the subject more often than close-by
TBH I'd have thought 1/800 would be more than enough even if used on a crop body, assuming VR was active of course. I can hand hold my 150-600mm at 600mm at 1/160 quite comfortably with VC enabled.Looking at the the images sent one of the main problems is (too low) shutter speed and movement, (by the subject and probably camera movement)
all shots are at low ISO's and most at 1/800th sec
as Wez says use much higher shutters speeds and push the ISO higher to get shots that have less "blur"
Practice long lens technique and then lower shutters speeds will be possible
all shots seem to have been taken at the same distance, but strangely enough the image with no focus point info is the only one that is half decent - apparently Gil use manual focus for this image!
TBH I'd have thought 1/800 would be more than enough even if used on a crop body, assuming VR was active of course. I can hand hold my 150-600mm at 600mm at 1/160 quite comfortably with VC enabled.
VR should be activated early enough that it stabilizes before taking the image. A stabilized image also helps the PDAF module...Also, my experience with VR is that when I have it on - when I activate the shutter, I notice that the view through the viewfinder 'jumps' and when it returns to normal, the focus spot may have 'jumped' from the intended initial placing before activating the shutter. At first I thought that might have been the cause of missed focus.
This would suggest to me that you're not half pressing the shutter first to acquire focus before taking the shot. At half press (or full press if you don't get focus first) the image can sometimes 'jump' when VR kicks in, however after this is should be stable. Whether shooting AF-S or AF-C I would always recommend half pressing the shutter first to acquire focus (and activate the VR) and then fully pressing the shutter (without releasing if first from the half press position). This should give you much better focus accuracy/hit rate, and will also avoid any issues when VR activates.Also, my experience with VR is that when I have it on - when I activate the shutter, I notice that the view through the viewfinder 'jumps' and when it returns to normal, the focus spot may have 'jumped' from the intended initial placing before activating the shutter. At first I thought that might have been the cause of missed focus.For that reason I have had it switched off, only switching it on when light is poor, and I have to drop my shutter speed below 1/focal lengh. Should I be using VR in circumstances like this when I have my shutter speed up above 1/800. Do you use VR when shooting BF at 1/1250 and above using dynamic AF?
Cheers!!
Whether shooting AF-S or AF-C I would always recommend half pressing the shutter first to acquire focus
And for those that don't like BBF?This is not what I recommend my students that setup up
BBF and deactivated focusing through half pressed SR
as its only function is to wake up and start the metering.
And for those that don't like BBF?
I'm always in favour of embracing new tech and ideas, but I am yet to prefer BBF no matter how much opportunity I give it But either way, my point was that (imo) it is better to lock/activate AF whether by means of BBF or half press shutter prior to taking the shot to allow time for the AF to acquire a better lock on, and also give time for the VR to become active and stable.Legitimate question, Toby!
Everyone has a favourite approach to the AF situation. Mine is
that I should be able to do anything, everything, any/every time
so I can increase the keepers. A ratio 10:500 as mentioned be-
fore is not a viable solution for one (me) to make an income of it.
Cameras come with fantastic integrated features that allow one
to perform the way it is required. In my book, not liking or refusing
to adopt an available technology that would make possible many
pictures that were not before, is as understandable as not lacing
one shoes before going out… my sons went though that!
my point was that (imo) it is better to lock/activate AF whether by means of BBF or half press shutter prior to taking the shot to allow time for the AF to acquire a better lock on.
I never use VR… almost taboo in my book.and also give time for the VR to become active and stable.
Some Nikons if you use BBF it overrides the focus acquisition before shutter release setting, dont know about the later ones though.
If it's set to AF-C focus should be constantly 'changing' whether using BBF or half shutter press, or do you mean the shutter release on focus setting?Some Nikons if you use BBF it overrides the focus acquisition before shutter release setting, dont know about the later ones though.