D800 focus with 1.4 prime lenses is very variable and inaccurate

Started Jan 20, 2013 | Discussions
primeshooter
Senior MemberPosts: 1,937
Like?
D800 focus with 1.4 prime lenses is very variable and inaccurate
Jan 20, 2013

Okay, so many have read my previous thread on my experience with this, I have had alot of pm's about this issue, of people who share my experience.

To re-iterate the problem, the D800 has poor AF accuracy when shooting with a 24-85mm focal length and wide open fast (f/1.4) primes at moderate to far distances, with low contrast subjects. I've found G lenses MAY be a little better but in all honesty D and G lenses have this problem. The camera tends to focus behind or in front of the intended point. AF fine tune is useless because up closer it focuses bang on. Sometimes it grabs correct focus at distance too, but the hit rate is very low.

The settings are AF-S, single, centre point or centre cluster, no area modes, no auto mode no dynamic area, just pure single servo and one focus box.

Now, take my example. For some weird reason this is saying this is a 50mm 1.4D lens. (It's the 1.4G lens, must be a dpreview fault reading the file). Please click for the original versions then +. Focus box was squarely on the child's face, perfectly over his face. But the camera as you can see, has clearly front focused. Infact so much so that the sharpest focus plane is on the man's right arm sleeve of the fleece. I took about 10 shots of this and I got half of them in focus and half like this. The trouble is, whilst his face isn't the highest contrast ever (in high contrast the camera has no problem whatsoever) it should be able to pick this up as the intended focal plane. Trying to focus on something the exact same distance isn't workable, but at this distance at f/1.4 it's noticeable that the child's face is not in focus. This is by far not the worst example I know, and I tried without the hat on the child, with the hat on the child, nothing helps really. I have a whole catalogue of photo's that have this problem now. In low light it's even worse and the hit rate lower. PDAF is terrible in this situation, face's just don't have enough contrast for the D800 unless there is a really contrasty light hitting the subject's face or they are at very close distance to you when shooting. I have extensively tested LV AF. Every time it nails it (as expected) and it can deal with distance and lower contrast as I can zoom in and define edges. But it's too slow, and I shouldn't have to use it on shots like these. If anyone wants to see the full size 36MP shot emailed to them to see how bad it is without dpreview's compression algos and resizing, drop me a pm, and I'll happily send it.



Nikon D800
If you believe there are incorrect tags, please send us this post using our feedback form.
Mauro.B
Senior MemberPosts: 2,343Gear list
Like?
My conclusion after my D800 went 3 times to Nikon service
In reply to primeshooter, Jan 20, 2013

is that AF module cannot perfectly cope with the vary shallow "effective dof" coming out from the combination of 36 megapixels and large apertures. Lenses with "short throw" cam, like the 14-24mm f2.8, suffer as much as, if not more, faster aperture lenses.

If you repeat single focusing at the same target, you will notice that at each half shutter press the distance scale changes a bit. That causes the focus plane to move forwards and backwards, in a way that may throw subjects out of focus depending on lens dof. The effect is magnified by the 36 megapixels.

I came to accept that, in the end. It is not fixable, it is a camera feature.

Best regards,

M

 Mauro.B's gear list:Mauro.B's gear list
Sony RX100 Ricoh GR Nikon D800E Leica M Typ 240 Fujifilm X-T1
Reply   Reply with quote   Complain
primeshooter
Senior MemberPosts: 1,937
Like?
Another example of the D800's poor focus ability:
In reply to primeshooter, Jan 20, 2013

Again, if anyone wants to see the full 36MP uncompressed image I will email it. On here, click original image then press "+".

Full size resized to 20mp:

Focus is clearly in front on his elbow, arm area. Again, true single point, AF-S no area modes, no auto.

I also have many that are badly focused behind the intended point. It seems the camera really has no idea where to focus alot of the time. (D and G lenses suffer - so please don't chime in and tell me it won't happen with a G lens). I own the 24mm 1.4G and the 50mm 1.4G and they both have it. I retook the next shot with contrast LV autofocus. Perfectly in focus, and the resolution of this camera allowed me to clearly see his big long eyelashes from this distance. With the PDAF I might as well put butter over my lens. This is not camera or subject motion, nor me moving or toddler movingout of the plane of focus when pushing the shutter. Like I said LV af gets it most of the time (much more than pdaf) and it takes about 3 seconds to take the picture in which alot of more movement could happen. Literally have so many shots like this now that aren't focused correctly.

Reply   Reply with quote   Complain
Art Jacks
Senior MemberPosts: 1,552
Like?
Re: My conclusion after my D800 went 3 times to Nikon service
In reply to Mauro.B, Jan 20, 2013

My recent experience using a couple of 1.4 G lens has shown that my slightest movement of the camera either by breathing or pressing  the shutter release after getting the green dot focus confirmation can cause OOF shots due to the very small amount of DoF at 1.4 but that may be my old age issues

Reply   Reply with quote   Complain
gl2k
Veteran MemberPosts: 3,232
Like?
Re: D800 focus with 1.4 prime lenses is very variable and inaccurate
In reply to primeshooter, Jan 20, 2013

Was there any movement involved ?  1.4f is very picky about every centimeter as your images show. At least to me it is hard to believe that a man holding a toddler is standing absolutely still  and the child is not moving at all.

Reply   Reply with quote   Complain
primeshooter
Senior MemberPosts: 1,937
Like?
Re: My conclusion after my D800 went 3 times to Nikon service
In reply to Art Jacks, Jan 20, 2013

Art Jacks wrote:

My recent experience using a couple of 1.4 G lens has shown that my slightest movement of the camera either by breathing or pressing the shutter release after getting the green dot focus confirmation can cause OOF shots due to the very small amount of DoF at 1.4 but that may be my old age issues

The issue is worse with AF-C. And I am very very steady...I have shot on a tripod with static subjects too. When I use LV autofocus and handhold I get a 100x better in focus result where intended in this situation. It's not subject movement or camera movement that is causing my issues, believe me I wish it was because I could fix that through practice.

Reply   Reply with quote   Complain
primeshooter
Senior MemberPosts: 1,937
Like?
Re: D800 focus with 1.4 prime lenses is very variable and inaccurate
In reply to gl2k, Jan 20, 2013

gl2k wrote:

Was there any movement involved ? 1.4f is very picky about every centimeter as your images show. At least to me it is hard to believe that a man holding a toddler is standing absolutely still and the child is not moving at all.

No, look at my second shot, same issue perfectly stationary staring at me. LV autofocus always nails it even when handholding I get a better result, and it takes about 3 seconds to take the picture in which the subject could have moved a foot out of the focal plane, yet it seems to nail focus much better. It's not subject movement or motion sorry, I can tell you this with certainty.

Reply   Reply with quote   Complain
Daniel Lauring
Veteran MemberPosts: 7,435Gear list
Like?
Re: My conclusion after my D800 went 3 times to Nikon service
In reply to Mauro.B, Jan 20, 2013

Mauro.B wrote:

is that AF module cannot perfectly cope with the vary shallow "effective dof" coming out from the combination of 36 megapixels and large apertures. Lenses with "short throw" cam, like the 14-24mm f2.8, suffer as much as, if not more, faster aperture lenses.

I've begun to wonder the same thing.  Perhaps in the past, we'd not have expected a perfect focus on such a small point and not have even tried F1.4 at this distance.  Or, perhaps we couldn't have noticed because we didn't have the resolution to notice the difference.  We are talking a entirely different pixel peeping level at 36 megapixels that wasn't possible with all but the slowest, most high end equipment years ago.

Having said that, with shallow depth of field, I often have to "tweak" the focus of the D600 too, despite the focus point looking like it is landing on the subject.  I go as far as to take multiple shots, turning the focus ring a tiny amount each time, knowing one of them will be optimal and I'll throw out the rest.

 Daniel Lauring's gear list:Daniel Lauring's gear list
Fujifilm XF 55-200mm F3.5-4.8 R LM OIS
Reply   Reply with quote   Complain
primeshooter
Senior MemberPosts: 1,937
Like?
Re: My conclusion after my D800 went 3 times to Nikon service
In reply to Daniel Lauring, Jan 20, 2013

Daniel Lauring wrote:

Mauro.B wrote:

is that AF module cannot perfectly cope with the vary shallow "effective dof" coming out from the combination of 36 megapixels and large apertures. Lenses with "short throw" cam, like the 14-24mm f2.8, suffer as much as, if not more, faster aperture lenses.

I've begun to wonder the same thing. Perhaps in the past, we'd not have expected a perfect focus on such a small point and not have even tried F1.4 at this distance. Or, perhaps we couldn't have noticed because we didn't have the resolution to notice the difference. We are talking a entirely different pixel peeping level at 36 megapixels that wasn't possible with all but the slowest, most high end equipment years ago.

Having said that, with shallow depth of field, I often have to "tweak" the focus of the D600 too, despite the focus point looking like it is landing on the subject. I go as far as to take multiple shots, turning the focus ring a tiny amount each time, knowing one of them will be optimal and I'll throw out the rest.

Try this when shooting a wedding

Reply   Reply with quote   Complain
primeshooter
Senior MemberPosts: 1,937
Like?
AF-C, and those suggesting it
In reply to primeshooter, Jan 20, 2013

To those posting about AF-C sorry to burst your bubble. It's the same or worse. Also to those suggesting the subject moving out of the focal plane during the time the button is pressed between focus, can you explain to me why the hit rate is 100x better when I switch LV contrast AF that takes about 3 seconds to lock focus then take the picture? Come on...it's pretty clear what we are dealing with here. The D800 has a focus system built to pull 12mp to focus, no more no less. Luckily half my work is large landscape prints. The 36MP resolution really shows the weakness of this PDAF system. The D700 concealed this quite well as it was only 12MP.

Reply   Reply with quote   Complain
Horshack
Veteran MemberPosts: 4,100
Like?
Can you enable 100% viewing in the gallery?
In reply to primeshooter, Jan 20, 2013

Focus is hard to evaluate without a 100% review.

Reply   Reply with quote   Complain
primeshooter
Senior MemberPosts: 1,937
Like?
Re: Can you enable 100% viewing in the gallery?
In reply to Horshack, Jan 20, 2013

Horshack wrote:

Focus is hard to evaluate without a 100% review.

pm me your email, I cannot enable 100% view as far as I can see without doing it for all my photographs.

Reply   Reply with quote   Complain
Daniel Lauring
Veteran MemberPosts: 7,435Gear list
Like?
Re: My conclusion after my D800 went 3 times to Nikon service
In reply to primeshooter, Jan 20, 2013

primeshooter wrote:

Having said that, with shallow depth of field, I often have to "tweak" the focus of the D600 too, despite the focus point looking like it is landing on the subject. I go as far as to take multiple shots, turning the focus ring a tiny amount each time, knowing one of them will be optimal and I'll throw out the rest.

Try this when shooting a wedding

Definitely less than ideal.  

I often use this procedure with the D600.  Meter lock with thumb, recompose.  Focus lock with shutter, recompose.  Fire off shot.  Switch to manual focus.  Fire off a few more tweaking the focus both ways from auto.  Too many times the first shot, isn't the best.  With some lenses the procedure is different.  For example the Sigma 70-200 doesn't seem to like to use it's close range focus so I manually focus it inside 3 feet.  If I don't, it often just hunts and doesn't focus at all.

 Daniel Lauring's gear list:Daniel Lauring's gear list
Fujifilm XF 55-200mm F3.5-4.8 R LM OIS
Reply   Reply with quote   Complain
rtf
rtf
Regular MemberPosts: 256Gear list
Like?
Re: I'm not surprised.
In reply to primeshooter, Jan 20, 2013

Hi. Maybe my views with regard to what I would personally expect from my camera equipment, are outdated, but what I see is a 36 million pixel sensor, f1.4 - with very limited depth of field, camera hand held, and a subject that is not 100% still. Your lens will not perform at it's best at f1.4 either. Why did you need to shoot at f1.4? You would still have isolated the background at f2, but gave yourself a fighting chance with a little bit more depth of field. I have a D800/D700/D7000 and I would not expect any of them to be at their best at f1.4. It's a big ask.

Regards.

RTF.

 rtf's gear list:rtf's gear list
Nikon D700 Nikon D7000 Nikon D800 Nikon AF-S Nikkor 16-35mm f/4G ED VR Nikon AF Nikkor 50mm f/1.8D +4 more
Reply   Reply with quote   Complain
rivercanyon
Junior MemberPosts: 27
Like?
Re: D800 focus with 1.4 prime lenses is very variable and inaccurate
In reply to primeshooter, Jan 20, 2013

primeshooter wrote:

The settings are AF-S, single, centre point or centre cluster, no area modes, no auto mode no dynamic area, just pure single servo and one focus box.

Hi,

Please clarify what your settings were.  AF-s has no center cluster option and no area mode option.  It is always a single pont only.  Are you using the focus and recompose technique?

Reply   Reply with quote   Complain
primeshooter
Senior MemberPosts: 1,937
Like?
Re: I'm not surprised.
In reply to rtf, Jan 20, 2013

rtf wrote:

Hi. Maybe my views with regard to what I would personally expect from my camera equipment, are outdated, but what I see is a 36 million pixel sensor, f1.4 - with very limited depth of field, camera hand held, and a subject that is not 100% still. Your lens will not perform at it's best at f1.4 either. Why did you need to shoot at f1.4? You would still have isolated the background at f2, but gave yourself a fighting chance with a little bit more depth of field. I have a D800/D700/D7000 and I would not expect any of them to be at their best at f1.4. It's a big ask.

Regards.

RTF.

Sorry I don't rate your questions. Lv contrast af works fine, at 1.4 so why not pdaf? The d700 had no trouble. I shot at f/1.4 because I wanted to. Also a slight front focused f/2 would still not have looked as nice as f/2 properly focused. If you can understand that live view autofocusing works for this type of shot, and usually takes at least 3 seconds with greater ability for movement of the subject and photographer then your argument is invalid Of why this isn't working with PDAf autofocus.

Reply   Reply with quote   Complain
primeshooter
Senior MemberPosts: 1,937
Like?
Re: D800 focus with 1.4 prime lenses is very variable and inaccurate
In reply to rivercanyon, Jan 20, 2013

rivercanyon wrote:

primeshooter wrote:

The settings are AF-S, single, centre point or centre cluster, no area modes, no auto mode no dynamic area, just pure single servo and one focus box.

Hi,

Please clarify what your settings were. AF-s has no center cluster option and no area mode option. It is always a single pont only. Are you using the focus and recompose technique?

I choose the centre point or one of the central cross sensors. Always single point, no area modes, no dynamic modes. No, I am not focusing and recomposing.

Reply   Reply with quote   Complain
rivercanyon
Junior MemberPosts: 27
Like?
Re: D800 focus with 1.4 prime lenses is very variable and inaccurate
In reply to primeshooter, Jan 20, 2013

It would be very helpful if you woud post screen shots of your with the focus point displayed.  That will allow others here to troubleshoot your issue for you.

On you second photo the child's lips do appear to be the are of best focus in the image.

Reply   Reply with quote   Complain
inasir1971
Senior MemberPosts: 3,187
Like?
Re: D800 focus with 1.4 prime lenses is very variable and inaccurate
In reply to primeshooter, Jan 20, 2013

Which lenses are you having trouble with apart from the 50 1.8G and what distances (in meters/feet)?

Reply   Reply with quote   Complain
primeshooter
Senior MemberPosts: 1,937
Like?
Re: D800 focus with 1.4 prime lenses is very variable and inaccurate
In reply to rivercanyon, Jan 20, 2013

rivercanyon wrote:

It would be very helpful if you woud post screen shots of your with the focus point displayed. That will allow others here to troubleshoot your issue for you.

On you second photo the child's lips do appear to be the are of best focus in the image.

in both images the focus point is perfectly over both faces. In both images the centre af point was used.

Reply   Reply with quote   Complain
Keyboard shortcuts:
FForum MMy threads