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Nikon 85mm f/1.8G - Sharp Enough?
  
 
snapsy
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p.3 #1 · p.3 #1 · Nikon 85mm f/1.8G - Sharp Enough?


fetopher wrote:
Focus distance on the hard drive was 9 feet, or thereabouts. Thanks!


Not sure you'll need the raw since mine looks similar to yours. Here it is shot on a tripod, 3-second exposure delay, processed in CS6 with all defaults. My lighting was contrastier thus the fringing.








Jan 08, 2014 at 12:08 AM
fetopher
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p.3 #2 · p.3 #2 · Nikon 85mm f/1.8G - Sharp Enough?


Snapsy, that looks very similar to what I'm looking at in my sample. Perhaps with the +11 fine-tune, I'm right in line with where I should be. I can't shake the feeling that my D800 and this lens just can't produce sharp images based on my real-world session with my wife and son (which prompted this thread), but I'll get out there and shoot in the real world at +11 and see how it goes.

Thanks for your help!



Jan 08, 2014 at 12:28 AM
rbromfield
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p.3 #3 · p.3 #3 · Nikon 85mm f/1.8G - Sharp Enough?


fetopher wrote:
Fantastic shot! Your photo was one I found before purchasing this lens and I was really wowed by it.

I tried to look at the original size on Flickr, but it looks like all I can get to is the large size (2048px wide). Any chance you could take a screen cap of the focused area at 100% and post here?

Thanks!


The following are straight out of camera, minus adding a watermark.
D800e f1.8 sharpness at 3 full size
D700 f2 sharpness at 5 full size
D700 f1.8 sharpness at 5 full size
D700 f2.2 sharpness at 5 full size

Hopefully these helped.



Jan 08, 2014 at 01:59 AM
jbouchard
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p.3 #4 · p.3 #4 · Nikon 85mm f/1.8G - Sharp Enough?


Someone please tell us because I don't know.... when the D800 focuses in Live view, does it use contrast detection off the sensor (like a D3200 does), or does it flip up the mirror and use the regular AF phase detection system (like the D700 does). If contrast detection, I would assume that would be as accurate as most people's manual focus, but is that true?


Jan 08, 2014 at 11:01 AM
fetopher
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p.3 #5 · p.3 #5 · Nikon 85mm f/1.8G - Sharp Enough?


jbouchard wrote:
Someone please tell us because I don't know.... when the D800 focuses in Live view, does it use contrast detection off the sensor (like a D3200 does), or does it flip up the mirror and use the regular AF phase detection system (like the D700 does). If contrast detection, I would assume that would be as accurate as most people's manual focus, but is that true?


As I understand it, live view uses contrast detect (CDAF) where was the view finder uses phase detect (PDAF). Here's a good writeup of the differences if you're interested (I was).

But, this got me thinking, the hard drive comparison between my photo and Snapsy's photo is using live view, or CDAF. Is it possible PDAF introduces my issues? I'm going to take the same hard drive shot again, but using the view finder (PDAF) and see it it compares to the live view shot. I'll post my results soon.



Jan 08, 2014 at 09:49 PM
fetopher
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p.3 #6 · p.3 #6 · Nikon 85mm f/1.8G - Sharp Enough?


Here's a test of roughly the same test as yesterday. First shot is using live view (CDAF), second shot is using view finder (PDAF). To my eye, there's quite a difference and CDAF looks sharper.

Snapsy (or others), is that what you would expect? If so, how much of a variance is there between CDAF and PDAF? I assume fine tune adjusting only affects PDAF. Is that correct?







Live view CDAF

  NIKON D800    85mm    f/1.8    1/60s    100 ISO    0.0 EV  







View finder PDAF

  NIKON D800    85mm    f/1.8    1/60s    100 ISO    0.0 EV  




Jan 08, 2014 at 10:08 PM
jbouchard
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p.3 #7 · p.3 #7 · Nikon 85mm f/1.8G - Sharp Enough?


With the D3200 I believe it says in the manual that CDAF is generally inferior to PDAF. I expect is says the same in the D800 manual.

I think you are right, the fine tuning only applies to PDAF, not CDAF. It makes sense... CDAF is looking at actual data from the sensor and trying to optimize it by getting sharp edges between pixels. Throwing in a fudge factor should only make it worse from there.

I think you owe it to yourself to try manual focus in live view. First use CDAF, then mess up the focus, and then do in manually, zoomed all the way in. There are people who use a magnifying glass to look at the LCD.

If you bought this from a place where you can return it and ask for another copy, I think it's time to do that.

Edited on Jan 08, 2014 at 10:40 PM · View previous versions



Jan 08, 2014 at 10:31 PM
 

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fetopher
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p.3 #8 · p.3 #8 · Nikon 85mm f/1.8G - Sharp Enough?


jbouchard wrote:
With the D3200 I believe it says in the manual that CDAF is generally inferior to PDAF. I expect is says the same in the D800 manual.

I think you are right, the fine tuning only applies to PDAF, not CDAF. It makes sense... CDAF is looking at actual data from the sensor and trying to optimize it by getting sharp edges between pixels. Throwing in a fudge factor should only make it worse from there.

I think you owe it to yourself to try manual focus in live view. First use CDAF, then mess up the focus, and then do in
...Show more

My understanding is CDAF is more accurate, but slower. PDAF is less accurate, but faster (and usable without having to fiddle with live view). Here's a great article that helped me understand how PDAF works (view finder).

As for your manual focus suggestion, I'm willing to give it a go. Do you propose I zoom in live view as much as possible, then focus manually?



Jan 08, 2014 at 10:37 PM
fetopher
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p.3 #9 · p.3 #9 · Nikon 85mm f/1.8G - Sharp Enough?


Here's my manual focus attempt. Not sure it's any sharper than the PDAF or CDAF shots. Also, I can't manually focus on my moving target (portraits of children, families, etc.), so even if this sample is markedly better, it does me no good. Interesting nonetheless.





  NIKON D800    85mm    f/1.8    1/80s    100 ISO    0.0 EV  




Jan 08, 2014 at 10:41 PM
fetopher
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p.3 #10 · p.3 #10 · Nikon 85mm f/1.8G - Sharp Enough?


Snapsy, would you care to share your thoughts on my FoCal test result chart using at the same focus point distance used to come up with +10.5 with Dot Tune? You can see the quality jumps up at +10 and +11, decreases at +12, then gets even better at +16, +18 and +20. Based on this chart, do you suppose +10.5 is an anomaly and something closer to +16 or +18 is correct, or would you toss out these results and stick with +10 or +11 based on the Dot Tune method?



Thanks!



Jan 09, 2014 at 04:48 PM
Hardcore
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p.3 #11 · p.3 #11 · Nikon 85mm f/1.8G - Sharp Enough?


I think if your 85mm F1.8 is anything like mine, you'll have a hard time calibrating it. While mine seems decently sharp wide open, it suffers from inconsistent focus in differing lighting situations. I struggle to find the right fine tune number because it always changes.


Jan 09, 2014 at 05:00 PM
dougfatheruk
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p.3 #12 · p.3 #12 · Nikon 85mm f/1.8G - Sharp Enough?


The 85mm 1.8G on my D3 is hellish sharp, it lacks pro glass micro contrast and isn't great on moving subjects.

For focus issues I try two things:

1) Download a printable focus chart, snap it wide open on a tripod. If you get loads of CA and blurry lines there's an issue.

2) Do the battery line up test, line up a series of batteries, cascade them adding a cm to each battery. Focus on one near the middle and see which one appears to be in more focus. One in front, one behind or the one you focussed on, very simple.

If your other lenses are fine then get the lens serviced, if it's part of a bigger problem get the body serviced. These types of problems drive you crazy, grrhhhhhh!!!!



Jan 10, 2014 at 10:09 AM
M635_Guy
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p.3 #13 · p.3 #13 · Nikon 85mm f/1.8G - Sharp Enough?


I read an article once by Roger C. from LensRentals where he talked about the fact that very small manufacturing variations in the body (lens mount, etc.) and lenses can produce exceptionally sharp pairings or bad pairings. I wonder if that is at work here. Honestly, your samples don't look very good to me, and at F8 on a tripod you shouldn't see much to complain about.

My 85 1.8G is really sweet on my D300s. (a handheld pic that isn't up to this thread, but is super-sharp when looking at the file - not sure Flickr does it full justice...)

LEE_2433-2.jpg by e24mpwr, on Flickr



Jan 13, 2014 at 02:13 PM
fetopher
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p.3 #14 · p.3 #14 · Nikon 85mm f/1.8G - Sharp Enough?


M635_Guy wrote:
I read an article once by Roger C. from LensRentals where he talked about the fact that very small manufacturing variations in the body (lens mount, etc.) and lenses can produce exceptionally sharp pairings or bad pairings. I wonder if that is at work here. Honestly, your samples don't look very good to me, and at F8 on a tripod you shouldn't see much to complain about.

My 85 1.8G is really sweet on my D300s. (a handheld pic that isn't up to this thread, but is super-sharp when looking at the file - not sure Flickr does it full
...Show more

Thanks for the feedback. I've read Roger's article as well. Actually, I've read dozens of articles (perhaps 50 or more) on focusing, fine tuning, etc. At this point, I feel I have a pretty good understanding of where things could be going wrong for my D800 and this 85mm 1.8 lens. None of it seems to apply to me exactly as my results seem to be inconsistent.

I would happily accept that this copy of this lens doesn't work with my D800, except this is actually the second copy of this lens I've had. The first went back right away as it was measurably bad and could not be fine-tuned into acceptable focus. Is it possible I could have received two "bad" copies in a row? Yes, but it's highly unlikely.

This second copy is better--much better even--but I'm unsure if it's "good enough." I've fine tuned using different methods, tested it in a plethora of conditions and reviewed my photos at 100%. The results leave me wanting more. I can get a sharp image with this lens, but my "hit" rate is really low (perhaps 2%).

I find myself frustrated and fighting to find sharp photos with this lens. To give myself a break from all my testing, I popped on my Nikon 50mm f/1.8D for a few minutes: 10 shots, 8 sharp. Felt good.

Here's a photo I took yesterday with the 85mm f/1.8. It is probably the sharpest I've taken with it yet. When you consider I've taken more than 1,000 frames with this lens, it's not really the best news. All in all, I'd say my 85mm 1.8 can achieve sharp focus, but it's extremely difficult to get it there and often inconsistent.

At this point my period for evaluation is almost up. My return by date is a couple weeks, but I don't know what else I can do to test it. I left deciding if I want the focal length at the cost of a low hit rate, or simply accept my D800 cannot handle longer focal lengths due to its front focusing and return it for a refund.






Focus on subject's right eye, no sharpening applied

  NIKON D800    85.0 mm f/1.8 lens    85mm    f/2.2    1/320s    800 ISO    0.0 EV  







100% crop of previous

  NIKON D800    85.0 mm f/1.8 lens    85mm    f/2.2    1/320s    800 ISO    0.0 EV  




Jan 13, 2014 at 09:12 PM
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