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Does my d800 have a focus issue?
  
 
avyaktha1
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p.1 #1 · p.1 #1 · Does my d800 have a focus issue?


I recently bought a used d800 and wanted to test its auto focus. I put my camera on a tripod and used live view autofocus and remote trigger , this is what I got

The photo is of a hindu deity krishna







I shot this with a d600 (borrowed from my friend) and used the same settings and the same lens (105mm 2.8).







The focus point was on the eye of the deity playing the flute for both the images.

I felt that d800 image isnt as sharp as the d600 image , as I notice only a slight difference . I wanted get an opinion from others if my camera has a AF issue or if this sharpness is generally acceptable?



Edited on Apr 06, 2014 at 01:11 AM · View previous versions



Apr 05, 2014 at 05:10 AM
Bob Jarman
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p.1 #2 · p.1 #2 · Does my d800 have a focus issue?


Can you change the links to display the images?

I've never had much success with Flickr links -gave up on that

Bob



Apr 05, 2014 at 02:15 PM
avyaktha1
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p.1 #3 · p.1 #3 · Does my d800 have a focus issue?


Thanks Bob for pointing it out

Changed https to http works now. Can someone please take a look and comment



Apr 06, 2014 at 01:12 AM
RustyBug
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p.1 #4 · p.1 #4 · Does my d800 have a focus issue?


If you check the RGB values of the two images, you'll notice that they are not the same. For instance the tip of her nose is about 15 point brighter in the D600 and her forehead (inside the red) is about 20 points difference greater than the D800.

Since sharpness is about perceived contrast, the higher tonal values of the D600 will create a perception of greater sharpness compared to the lower values of the D800. I suspect that the camera contrast/sharpening algorithms are slightly different or the jpg processing settings are different between the two cameras. Also,working from different file sizes can require different sharpening parameters to achieve the same perceived sharpness.

That being said ... from these pictures alone ... I don't think you have a focus issue, just a processing one (at least to a certain degree).





D800




Apr 06, 2014 at 04:51 AM
 

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Bob Jarman
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p.1 #5 · p.1 #5 · Does my d800 have a focus issue?


First, coming from someone whose visual acuity is sometimes in question and with my having been told cataract surgery is 5 or 6 years down the road, the first image appears marginally sharper to me. I am basing this on the area of the blossoms on the leftmost figure.

Frankly, I don't see a whole lot to be concerned about. Having been able to resist the calling of a D700 and D800 over the years, and having ultimately settled for another form of camera, I will note that everything I've read about the D800 is that it is a superb machine (often mentioned as the standard for IQ comparison), but it is unforgiving. That is, proper technique is an absolute requirement to achieve optimal results. Assuming no variance in technique, you could perceive a difference in performance in the lens across two platforms.

Or, as Kent points out, underlying differences in the renditions produced by each unit are at work. Truth is, if any of the above, or other variables (MP count etc.) are at play, we'll never know.

Relax and enjoy the new gear!



Bob

<later> In addition - for a fair comparison an even baseline is necessary; two D800's - one a known performer and your acquisition.



Apr 06, 2014 at 01:22 PM
avyaktha1
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p.1 #6 · p.1 #6 · Does my d800 have a focus issue?


thanks a ton for the comments


Apr 06, 2014 at 06:07 PM
FarmerJohn
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p.1 #7 · p.1 #7 · Does my d800 have a focus issue?


Also, if you haven't read about it already, autofocus is variable in performance shot-to-shot, even on perfectly micro-adjusted camera/lens combos. I'd suggest some of the Lens Rentals blog articles by Roger Cicala - http://www.lensrentals.com/blog/2012/07/autofocus-reality-part-1-center-point-single-shot-accuracy




Apr 07, 2014 at 06:14 AM





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