Possible faulty AF, or am I expecting too much?

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Gil
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#1
After realising that many of my photos have been way off the mark in terms of AF accuracy, with 2 seperate lenses on my D500 - I'm wondering if I potentially could have a AF issue in-body.

I took over 400 pictures today with my 200-500 in excellent conditions on a mono-pod and after tweaking the fine tune settings throughout all 40 possible settings, I was unable to achieve much difference in overall sharpness. In fact, I found that using Manual Focus, I was able to get better results that using Auto Focus. The reason I question my AF is I also recently took pictures at a friends wedding, and found that consistently through a number of the same photos, ie bursts, my focus would be out, even although my camera is set to only shutter release when in focus.

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 - I'm just wondering if I'm expecting too much from my combo? I just find that if birds are this far away, I just pretty much give up, as I'm not going to get the results I'm looking for.

Here's probably the very best I got with AF, but I would say it's too soft to keep? What are your opinions? How many in focus photos should I be getting? 5 out of 10, 9 out of 10? I'm lucky to get 1 in 50 at the moment.

Full image


HSC_5904_full
by Gilbo B, on Flickr

Cropped image


HSC_5904_full 1
by Gilbo B, on Flickr
 
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#4
I think your too far away and any softness most likely heat haze ,what iso /shutter speed - single focus point ?
Rob.
 
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Gil Bev
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#5
I think you are right regarding the heat haze, I wasn't at the edge of the water, some way back. I was getting an iso of between 100 and 500, so quite low. Shutter speed ranged from 1/500 up to 1/1250. Yes, single focus point
 
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#6
I really do think distance and heat haze going on that info top pic quick edit sharpened and a little lighter.
Rob

42062989621_8b0a3e61d7_b.jpg
 
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#7
I think Rob is probably correct regarding distance/heat haze, but also I see you are shooting at f8/f11 in the above shots.
My 200/500 on my D500 is very sharp at f5.6, might be worth upping the shutter speed and shooting at f5.6.
Could be worth a try before blaming the camera body and also filling more of the frame with the subject if possible.
I mainly shoot aircraft and the keeper rate is very good, hope you get it sorted as the combination of the D500 and 200-500 (for the price) is excellent.

Cheers - Paul.
 
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Gil Bev
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#8
Perhaps I'm expecting too much from subjects too far away!! I have been getting much better results with subjects that are much closer.

My thinking was that by stopping down - it increases the DOF increasing the likely hood of a sharp image, but having had a look at the DOF calculator, even at f5.6 the DOF is 13m for a subject 100m away

Maybe the AF is not designed to work to that level of accuracy for subjects so far away, or perhaps the slight movements on my mono-pod are enough to throw any AF out when I come to take the picture.

It was pretty hot, so heat haze probably as you both have said had an influence too
 
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Gil Bev
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#10
OP - I can understand your frustration.

Ideally, using a focus chart or even a stationary target with a ruler beside so we can get an idea as to how far out this is. At your friends wedding, which lens were you using?

For the birds - are you using AF-S or AF-C?
Yes, I'm considering trying Lensalign or Reikan FoCal as my attempts with a ruler weren't conclusive enough. It just wasn't giving me solid results. At least when properly tuned, I can eliminate that from possible reasons for soft images. I always shoot AF-C for my birds

I was using the 16-80. Again not fine tuned - but the majority of photos were very acceptable, but I just got more than I'm happy with that were way out - and had to be thrown away - not just 1, but a whole burst. I'm going to review the settings I used in case I had switched over to AF-S when using my 16-80, which would explain why the bursts were sometimes consistently out of focus. I used BBF, and shooting AF-S would have meant that the autofocus wouldn't have tried to correct the focus in-between shots
 
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Gil Bev
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#11
I went through my AF settings and found that under a3 - Focus tracking with lock-on, my 'Blocked shot AF response was set to a value of 2. I'm wondering that for subjects further away, if I were to AF on the background inadvertently, any images in the burst to follow would still be locked onto the background even with the focus point on the subject. I'm wondering if this could be the culprit!! I've set it to 1 now. I'm also set to 'Subject motion' - erratic.

I had a look through my pictures from the wedding - and I was using AF-C. Some of the bursts where I missed focus started with a photo where the focus point was half on the subject, half on the background. I'm wondering if the above blocked shot setting could have caused the camera to remain on the background throughout the burst even although the focus spot was then properly placed on the subject for the remainder of the photos.
 
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#12
I do think heat haze is affecting these. I have seen some stunning wildlife shots with this lens. The Nikon 200-500 is renowned as an excellently sharp lens but at closer focal distances. It’s infinity performance isn’t as good and is poor in the corners at longer focal distances.

You will never be able to properly adjust the focus on a Nikon lens because the bodies will only allow a single adjustment i.e at one focal length and one focus distance where in reality you have numerous focal lengths, 200,300,400,500 and focus distances from mfd to infinity.
 
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#13
Shooting a bird from 100m away and then cropping to 1:1 you’re never going to get great image quality tbh, and you’re not going to see fine feather detail. If you have haze or any other atmospheric aberrations then this is only going to compound the issue.

I’m only on the phone at the mo so can’t properly critique the photos but my initial thoughts looking at the pics is that they are just suffering from being heavily cropped.

Yes I can crop my D850 (and before that D750) to 1:1 and get usable images, but they are just that usable rather than being great. Of course, shooting a close subject and cropping 1:1 generally yields better results than shooting distant subjects and cropping. I wouldn’t want to crop to 200% or 300%, even for small screen viewing though.

DSC_5895 looks like it’s focussed on the water rather than the bird though so this isn’t going to help obviously.

And lastly most lenses are generally sharper stopped down a stop or two so I would expect your lens to be sharper at f8 & f11 than f5.6.
 

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#14
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#15
but the majority of photos were very acceptable, but I just got more than I'm happy with that were way out - and had to be thrown away - not just 1, but a whole burst.
Here you go!
If the camera is capable of producing acceptable results, it’s not the cameras fault.
 
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#16
Just been through your Flickr stream and your close up shots are spot on ,but anything over a distance is a mush . Which leads me to suspect there is a resolution problem with that lens at longer ranges . I had similar with the sigma .you can only blame heat haze on one particular day place .so it’s worth going back through your files picki out the long range pics .... especially the winter ones ..... and be brutally honest with yourself . Then decide what to do
 
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#17
I went through the flickr too and I agree - the shots closer up look better.... it's hard to diagnose a potential lens issue remotely but it could be technique that is causing some of this.

One thing i found to help whilst hand holding long lenses on distant, moving subjects is set the AF tracking sensitivity to low so it holds the AF point slightly longer, that may help.
 
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#18
It could well just be that the lens is spot on for close work but needs af adjustment for distance. This will be the same with any Nikon lens though as I alluded to above and nowt you can do.
 
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#20
Are you using the built-in fine tune system as i found it to be rubbish on my D500, think i read Nikon can fine tune at different FL but i could be wrong.
One of the reasons i got rid of my D500 was i could only manage a 400mm lens on it and i didnt like the large crop results.
 
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#21
Don't forget that any movement will be amplified at the distance of the subject. so with a shutter speed that slow any movement will show up like it has.
Plus Inc all the other reasons people have said.
 
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#23
Very long lenses are just a lot harder to use well than some folks think. The lens must obviously be properly calibrated, the camera must be capable (D500 certainly is) and AF settings must be optimally selected. Knowledge, practise, and more practise.

- Atmospheric pollution kills sharpness over distance - heat haze, moisture and general crap in the air. With wildlife, getting as close as possible is probably rule number one and just throwing more and more focal length at it just makes things worse.
- Dull light, eg on an overcast day, produces flat looking images.
- Cropping severely reduces all aspects of image quality.
- Use high shutter speeds, even if that means shooting at maximum aperture and high ISO.
- The popular hand-holding rule (shutter speed = one over effective focal length) is a very rough guide at best, it's a minimum and not a recommendation, everyone is different, long/heavy lenses are harder to hold steady.
- When shutter speeds are marginal, every shot will be affected differently - some badly blurred, some acceptable, some good. There's safety in numbers, so shoot lots.
- Effective focal length is the actual focal length x crop factor (1.5x on a D500). Then if you crop the image, that is another increase in effective focal length. Use a monopod and have image stabilisation on.
- Image stabilisation does nothing for subject movement and birds, even when apparently moving slowly, tend to use short, fast, jerky movements.
- Nobody, even the most experienced with the best equipment, will nail critically sharp images every time. Success is about knowing the limitations, minimising the pitfalls, and tipping the odds in your favour.
 
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#24
Long lens technique needs practice (and a good set-up)

with the images in question - if you are using single cell focus on the birds head at a distance - it is very easy to mis the focus when you press the shutter

before diving into lens calibration etc., you should always check your focus point on any images that you feel are OOF - as I said this can be shown quite easily using software that is available

many "problems" are usually user error
 
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#25
Long lens technique needs practice (and a good set-up)

with the images in question - if you are using single cell focus on the birds head at a distance - it is very easy to mis the focus when you press the shutter

before diving into lens calibration etc., you should always check your focus point on any images that you feel are OOF - as I said this can be shown quite easily using software that is available

many "problems" are usually user error
That will tell you which AF point was used, but not necessarily where it was when the focus was set.
 
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#27
Looking at the images - it will tell you if the OP got her focus correct, which should be a basic starting point - certainly to be checked before considering "possible faulty AF"
This is the first thing that I would check - was focus achieved? - it's all in the EXIF

My images not the OP's - both distance shots




 
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Gil Bev
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#28
Thanks for the input guys. All of my photos were centre focused - the single focus spot was not moved from the very centre of the frame. Camera was set to focus priority so wouldn't fire unless focus was achieved.

Out of curiosity @BillN_33, what software and how did you get the above photos to show with their focus point selection?
 
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#29
Thanks for the input guys. All of my photos were centre focused - the single focus spot was not moved from the very centre of the frame. Camera was set to focus priority so wouldn't fire unless focus was achieved.

Out of curiosity @BillN_33, what software and how did you get the above photos to show with their focus point selection?
Hi Gil,

As Bill is offline, he (and I) use this plugin for Lightroom : http://www.lightroomfocuspointsplugin.com/

It's very handy.

Btw, on your images above, looks like atmospheric haze to me. It's so often overlooked by people that use long lenses!
 
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#30
Thanks for the input guys. All of my photos were centre focused - the single focus spot was not moved from the very centre of the frame. Camera was set to focus priority so wouldn't fire unless focus was achieved.

Out of curiosity @BillN_33, what software and how did you get the above photos to show with their focus point selection?
Aaah the penny drops .this in fact means that your focus point is focussing beyond the bird in most cases ,and as the focus point area sees the water as in focus you get a confirm .in my book this is entirely wrong and user error ,you need to take more time and ensure the birds eye is critically sharp ,and depending on your camera a smaller focus point would help .
 
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#31
Thanks for the input guys. All of my photos were centre focused - the single focus spot was not moved from the very centre of the frame. Camera was set to focus priority so wouldn't fire unless focus was achieved.

Out of curiosity @BillN_33, what software and how did you get the above photos to show with their focus point selection?
You can get a focus point plug in for Lightroom which shows this info. Just google focus point plus gin for Lightroom and you should find it.
 

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#32
All of my photos were centre focused - the single focus spot was not moved from the very centre of the frame
I don't have the Lightroom plugin but I've overlaid the D500 focus point pattern onto a couple of the OP's images.

Some things that spring immediately to mind:
  1. The central focus points are on the bird's body, not its head.
  2. At that range, the focus points are quite large relative to the bird and it's not clear exactly what the camera has focused on.



 
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#33
Thanks for the input guys. All of my photos were centre focused - the single focus spot was not moved from the very centre of the frame. Camera was set to focus priority so wouldn't fire unless focus was achieved.

Out of curiosity @BillN_33, what software and how did you get the above photos to show with their focus point selection?
Just because you think you have achieved focus confirm, (on the Heron's head), it does not mean that you have - when you press the shutter if you do not have good technique the focus point will move slightly especially on distance shots - certainly enough to push your image OOF. (If the subject is nearer the target area is bigger and if the point moves when you press the trigger it may still stay on the target)

Now you have a link to the plug in re post your images showing the focus point and you will see if it is confirmed or not - if it is then look at other possible areas for the OOF images

As I said do not dive into in-camera lens adjustments until you have check several areas of your photography as many problems are simply user error. In camera lens adjustment are more difficult on zoom-lens and you could, will, just go around in circles

We have discussed this (free) plug in - in the past - it also gives you information about your shot
 
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#34
I don't have the Lightroom plugin but I've overlaid the D500 focus point pattern onto a couple of the OP's images.

Some things that spring immediately to mind:
  1. The central focus points are on the bird's body, not its head.
  2. At that range, the focus points are quite large relative to the bird and it's not clear exactly what the camera has focused on.



Interesting... even wide open, surely the depth of field would be sufficient on that lens at this distance for an AF point on the body of the bird?
 
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#35
Interesting... even wide open, surely the depth of field would be sufficient on that lens at this distance for an AF point on the body of the bird?
The software shows ALL focus points even if only a single cell is used - if the OP used the spot, (single cell) method - she probably missed the head - (easy to do) and the focus point was not on the head - unless Gils post an image, (or sends me the RAW file), we just do not know were the camera was focused - if no RED confirm then the camera just did not focus accurately as it uses contrast detect, (or phase detect?), to focus.

The above must be just an example - you need the original file to show the accurate position - this will also give the distance and DOF
 
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#36
Interesting... even wide open, surely the depth of field would be sufficient on that lens at this distance for an AF point on the body of the bird?
Yes, if the AF point is on the body of the bird, which appears to be the case here.
 

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#37
unless Gils post an image, (or sends me the RAW file), we just do not know were the camera was focused ....
I don't think it's possible to know for certain what the camera was focused on. All you can say is which focus point was used, but you can't be sure exactly what was under that focus point when focus was acquired. Can you?
 
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#38
Interesting... even wide open, surely the depth of field would be sufficient on that lens at this distance for an AF point on the body of the bird?
That was my belief too. At f8 the depth of field at that distance should mean that by getting the body in focus the entire bird should be in focus too. Even at f5.6 the DOF is much greater than the size of the bird.

My worry when the head is smaller than the focus square and when it moves the most I'd miss focus and get the water behind - so I had been aiming for the body for distant subjects, and the eye for close subjects.

I noted that the image looked much better through the viewfinder compared to the resulting image but I guess that's because you can't zoom in until after the photo is taken

I'm going to use FoCal to fine tune and try again with a tripod instead of a monopod.

At higher shutter speeds is it necessary to use VR when on a tripod? My tripod is aluminium and there is noticeable shake when viewing through the viewfinder. Would a remote shutter be a good idea? I'm also going to try on a less hot day to try and reduce heat haze. I would have expected heat haze to have been more apparent through the viewfinder or on liveview.

Also going to download that plugin and try using it on quite a few of my RAWs. Will update soon
 
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#39
That was my belief too. At f8 the depth of field at that distance should mean that by getting the body in focus the entire bird should be in focus too. Even at f5.6 the DOF is much greater than the size of the bird.

My worry when the head is smaller than the focus square and when it moves the most I'd miss focus and get the water behind - so I had been aiming for the body for distant subjects, and the eye for close subjects.

I noted that the image looked much better through the viewfinder compared to the resulting image but I guess this is normal on mirror cameras.

I'm going to use FoCal to fine tune and try again with a tripod instead of a monopod.

At higher shutter speeds is it necessary to use VR when on a tripod? My tripod is aluminium and there is noticeable shake when viewing through the viewfinder. Would a remote shutter be a good idea? I'm also going to try on a less hot day to try and reduce heat haze. I would have expected heat haze to have been more apparent through the viewfinder or on liveview

I can't comment on the specifics - as I don't shoot birds - it looks too hard :D

I personally would have focused on the body at long distances and relied on the depth of field to carry me through - the risk of missing focus on the head is too high in my opinion.

There are a lot of users on here that will be able to comment on the specifics of VR use whilst on a tripod and remote release, it all sounds like good fun!

I would definitely try the AF fine tune, I do on my lenses and see a big difference. - I started a thread a few months ago when i was pulling my hair out over a prime lens I was struggling with. - Nailed it in the end.

On the AF fine tune methods, there are a few to try out. I found a cereal box and ruler to be the best way for me, but using live view and the dot tune method are also accepted practices.
 
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#40
I don't think it's possible to know for certain what the camera was focused on. All you can say is which focus point was used, but you can't be sure exactly what was under that focus point when focus was acquired. Can you?
The software shows the focus point - in the two examples I posted I used single cell and the red square indicates the focus point and focus confirm - (with shots like the Kingfisher I would have taken maybe 10+ images and being a very small bird would automatically check if I had got the focus spot on when I got back to my computer - at least 50% would have been slightly off, because of slight camera movement - when you press the trigger and even mirror slap) - if no RED confirm is given it indicates that focus was not confirmed and the image will be OOF, to a more or a lessor degree.

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
 
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