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Archive 2012 · D800 problems. FocusTune, Nikkor 24-70 f/2.8 :(
  
 
kazinvan
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p.1 #1 · p.1 #1 · D800 problems. FocusTune, Nikkor 24-70 f/2.8 :(


Purchased FocusTune, tested my 24-70 on the D800. This D800 has already been to Nikon to fix the left AF issue.

I tested a few things using the software, which is great to automate the analysis and take the guesswork out of this testing.

1. AF adjustment 24mm : Best at +20 but unknown if it should actually be higher than that. Even at +20 my best sharpness value is just under 17000 (not sure what units are used).

2. AF adjustment at 70m: Best at 0 and sharpness value at 38000. Image is MUCH sharper at 70mm.

So my lens is much sharper at 70mm than at 24mm. I'm not sure if that is the lens design or if I just can't go high enough on the AF fine tune to get a sharper image at 24mm. I suppose I can test this with some live view manual focus shots, and I may do that.

The problem is that there isn't a good AF fine tune setting for me at this point. 0 gives me best sharpness at 70mm, +20 best at 24mm. Setting to +10 just makes them both bad.

3. Aperture comparison, 24mm. Best at f/7.1 but fairly even from about f/5 to f/8. Stopping down the lens helps sharpness so shooting at f/5.6 is likely best bet for me.

4. Focus point comparison. I still have the left AF problem There is a huge difference in sharpness between the left AF points and the Center/Right/Top/Bottom.

Bottom line, lens and camera need to go back to Nikon. Joy.



Nov 29, 2012 at 12:54 AM
Lance B
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p.1 #2 · p.1 #2 · D800 problems. FocusTune, Nikkor 24-70 f/2.8 :(


A few comments:

The 24-70 is supposed to be sharper at 24mm than at 70mm, but only by a smidgen.

See this on DP Review:
http://forums.dpreview.com/forums/post/42121375

In other words if you need more than -/+20 in AF Fine tune, then use the "Default" AF setting in AF Fine tune, not the "Saved Value" and delete the entry in the list of saved values. The "Default" setting is basically for the camera and is 2.5x coarser than the AF Fine tune setting. So, if you need -25 in AF Fine tune, then you only need -10 in the "Default" fine tune.

Unfortunately, this cannot help with the huge disparity between the 24mm setting and the 70mm settings.



Nov 29, 2012 at 01:23 AM
kazinvan
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p.1 #3 · p.1 #3 · D800 problems. FocusTune, Nikkor 24-70 f/2.8 :(


Here are the actual results.

1.


2.


3.


4.

Disregard the fact that left side is sharper, body not tuned for center focus point. Left side is clearly different than center, right, top, and bottom.

My sharpest 24mm shot (fine tune +20)


My sharpest 70mm shot (fine tune -5)



Nov 29, 2012 at 01:30 AM
 

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kazinvan
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p.1 #4 · p.1 #4 · D800 problems. FocusTune, Nikkor 24-70 f/2.8 :(


Lance B wrote:
A few comments:

The 24-70 is supposed to be sharper at 24mm than at 70mm, but only by a smidgen.

See this on DP Review:
http://forums.dpreview.com/forums/post/42121375

In other words if you need more than -/+20 in AF Fine tune, then use the "Default" AF setting in AF Fine tune, not the "Saved Value" and delete the entry in the list of saved values. The "Default" setting is basically for the camera and is 2.5x coarser than the AF Fine tune setting. So, if you need -25 in AF Fine tune, then you only need -10 in the "Default" fine tune.

Unfortunately, this cannot
...Show more

Lance, thanks for the info. I didn't realize that default was more coarse. However, that applies to any lens you mount on the camera, right? I haven't tested my other lenses, so that may not be a good setting for me to go with.




Nov 29, 2012 at 01:32 AM
Lance B
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p.1 #5 · p.1 #5 · D800 problems. FocusTune, Nikkor 24-70 f/2.8 :(


kazinvan wrote:
Lance, thanks for the info. I didn't realize that default was more coarse. However, that applies to any lens you mount on the camera, right? I haven't tested my other lenses, so that may not be a good setting for me to go with.



It does apply to any lens you mount on the camera, but this can be circumvented if you enter it into the Lens List of 20 memorised lenses. The point of the Default setting is that it adjusts the camera to a set point if the camera's AF is out by a certain amount. You only use the memorised list of lenses for those lenses that do not fit with the global alteration of the Default (camera) setting.

So, let's assume the camera's AF is out by +5 and affects all your lenses by this amount. You would not enter any of your lenses into the Saved List of Lenses. However, if one or more of your lenses is affected differently than the camera's global Default setting of +5, then you would set your individual lenses to the AF Fine tune that suits that lens best and then save it to the Saved List of Lenses.

Unfortunately, the Default value is not additive to the Saved value. I think it probably should be due to the fact that if the camera is out by +5 (in reality 2.5x that figure due to it's coarse value = +12.5), I think it would stand to reason that all lenses would be affected by the camera being out by this amount as most lenses are probably close to the correct AF fine tune in the first place. You may only then need a small tweaked amount in the Saved Value in order to "fine tune it" or possibly none at all.

The point of the fine tuning adjustment is to adjust for the tolerances of the whole system and is to be expected as tolerances occur. If we assume that Nikon has a +/-5 or +/-10 as their tolerance for both the manufacture of camera and lenses, than even at +/-10 lenses should, and I think mostly do, fall into the +/-20 range of the AF Fine tune as this would allow for a +/-10 for the lens and for the camera being additive as a worst case scenario.




Nov 29, 2012 at 01:58 AM
kazinvan
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p.1 #6 · p.1 #6 · D800 problems. FocusTune, Nikkor 24-70 f/2.8 :(


Good to know, thanks Lance. I still have the issue of the wildly different fine tune settings for the extreme ranges of the 24-70 range. I sorted my images in LR by that lens, then took a look at the focal lengths I shoot at. Seems to be about an even split between 24mm and 70mm, so that isn't much help

I think I'll test my other lenses then send the whole mess to Nikon to deal with. The body still has the left sensor AF issues it did so Nikon didn't fix it.



Nov 29, 2012 at 04:02 AM





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