D90 back focusing?

Discussion in 'Nikon' started by francis_d, Jan 4, 2010.

  1. Hi,
    I would like to get some experienced user opinions on whether my D90 has back focusing issues.
    BACKSTORY
    I got my D90 in Oct 2009 (first DSLR) and picked up a fair amount of knowledge in that short time IMO. I understand DoF concepts (where aperture, focal length, and subject distance affect DoF) and also having a fast enough shutter speed to avoid motion blur.
    I wanted to be able to shoot indoors in lower lighting conditions, so I picked up a Tamron 17-50mm f/2.8 Di II (non-VC model). Shooting people wide open (f2.8) I wasn't able to get very many shots in focus. It seemed to be focusing a little behind the subject, so I'd have their hair on the side of the head in focus with the eyes blurred. I even used single point focus and focused on the eyes without recomposing to eliminate the possibility of the plane of focus being shifted. I read about people having front/back focus issues with the Tamron 17-50, so I ended up returning it because of that and the 2/3 of a stop didn't really let in that much more light.
    I ended up getting a Nikon 35mm f/1.8G AF-S DX and discovered I was having the exact same back focus issues AGAIN while shooting wide open. I tried stopping down to 2.8 with no luck. Only when stopped down to about 3.5-5.6 was I able to get the subject's eyes in focus. My problem shots were even in the 1/60-1/80s shutter speed range for relatively still subjects (people). This led me to believe that it's not the two lenses with the back focus problem, but the D90 itself. I realize that each lens may not be perfectly calibrated with +/- variances (Ref: http://www.lensrentals.com/news/2008.12.22/this-lens-is-soft-and-other-myths).
    In comparing my printed photos with my relative's D40 with the 18-55mm f/3.5-5.6 kit lens and his photos were MUCH sharper around the edges of people and eyes compared to mine.
    TEST CHART SHOTS
    I printed out a focus chart (from here) and ran the test on the 35mm and 18-200mm lenses. Of course with the latter I can't get as shallow DoF.
    I mounted my camera on a tripod and set a 2sec countdown with the shutter delay on and flash fired. I tried my best to eyeball a 45 degree angle down towards the paper on the floor. I even did some shots hand held at varying angles and in those cases, I still had back focus problems.
    All shot with AF single point center, focused on the letter "h" in "Focus here").
    Nikon AF-S 35mm F1.8G DX
    35mm f/1.8, 1/80s, flash, tripod, Aperture Priority http://i265.photobucket.com/albums/ii240/dialeleven/D90%20test%20chart/DSC_4311.jpg
    35mm f/2.5, 1/80s, flash, tripod, Manual Mode http://i265.photobucket.com/albums/ii240/dialeleven/D90%20test%20chart/DSC_4319.jpg
    35mm f/3.5, 1/80s, flash, tripod, Manual Mode http://i265.photobucket.com/albums/ii240/dialeleven/D90%20test%20chart/DSC_4322.jpg
    35mm f/1.8, 1/80s, flash, handheld, Aperture Priority http://i265.photobucket.com/albums/ii240/dialeleven/D90%20test%20chart/DSC_4342.jpg
    Nikon 18-200mm f/3.5-5.6G IF-ED AF-S VR DX
    18mm f/3.5 1/30s flash, tripod, Aperture Priority http://i265.photobucket.com/albums/ii240/dialeleven/D90%20test%20chart/DSC_4312.jpg
    18mm f/3.5 1/30s flash, handheld, Aperture Priority http://i265.photobucket.com/albums/ii240/dialeleven/D90%20test%20chart/DSC_4333.jpg
    From the samples, do you think the D90 has back focus issues and should be sent into Nikon for calibration?
    P.S. I bounced back from Aperture Priority to Manual to see if I could get the 35mm shots brighter.
     
  2. Camera's do not have focus issues (unless the film holder/sensor is off axis or improperly distanced,)lenses are the culprit when talking about back/front focus.
     
  3. I moved from a D80 to a D200. After the move I could not get a sharp picture with any of my lenses. Sending the D200 camera body to Nikon for service was the only way to get it resolved. I wish I had done it sooner. Send the Body to Nikon for cleaning and adjustment.
    Dave
     
  4. I agree with David. Send your camera and lens to Nikon and they will correct it for you.
    "D40 with the 18-55mm f/3.5-5.6 kit lens and his photos were MUCH sharper around the edges of people and eyes compared to mine" This is to be expected as the DOF is significantly greater. If you shot with your 35mm at the same aperture as the 18-55mm, the results would be virtually identical.
     
  5. 'D40 with the 18-55mm f/3.5-5.6 kit lens and his photos were MUCH sharper around the edges of people and eyes compared to mine' "This is to be expected as the DOF is significantly greater. If you shot with your 35mm at the same aperture as the 18-55mm, the results would be virtually identical."​
    Elliot, sorry I should have specified that my shots with my 18-200mm f/3.5-5.6 lens (shot in P mode as I was first learning) were not as sharp as my relative's D40 with the 18-55mm f/3.5-5.6 kit lens where he shoots in AUTO mode. To me that would seem like there's something off with either my lens (both of them though?) or the body in which case I think sending it in to Nikon would be a good idea.

    It seems that shooting the test chart may not be the best test, so next time I'll try taking shots with my lenses on the D40 to see if I'm able to shoot a real subject (people) wide open and get the eyes in focus vs on the D90.
     
  6. You're comparing apples and oranges. Shoot raw and then compare the two after adjusting equally in NX Capture or ViewNX.
    BTW: the 18-55 outperforms the 18-200 easily! Don't be mistaking about the price. Ken Rockwell calls it his sharpest lens; just as sharp as the 17-55 2.8 that costs at least 10 x more. At low ISO tha D40 is excellent as well, with a native 100 ISO versus 200 for the D90.
     
  7. francis, try shooting test shots on a wall and not on the floor. that way your lens is perpendicular to the target. i can say that the culprit wasn't the lens nor the camera.
    or if you want your approach, simply use 3 soda cans lined up away from you in an offset. then focus on the middle can. the sheet that you used i believe, is only good mounted flat on a wall.
     
  8. Francis, I also noticed similar problem, especially when comparing pictures between the D90 and D40. I raised the issue here: http://www.photo.net/beginner-photography-questions-forum/00VLOE
    Although I dont have the 18-200 lens, I would agree that the 18-55 is a very good lens. I did further testing using different lenses as well, however, I kind of concluded that 1) the default settings between the D90 and D40 are not the same, and that if I increase the sharpness setting of the D90, I get similar results as compared to the D40. That was just my quick and dirty conclusion....you may have a different result/reason.
     
  9. I thought I was going crazy or I have really bad technique when I got a lot of soft shots with my D90 and the 50mm 1.4G wide open. I performed a lens focus test found here http://regex.info/blog/photo-tech/focus-chart and it's pretty evident that it's back-focusing for me. I also tried the same test on my 35mm 1.8 and my kit lens 18-105. Surprisingly, all of them back-focused and it was even more evident when I was shooting at F/4.0. I am going to be dropping off the body with all 3 lenses at Nikon this week for them to calibrate since everything is under warranty.
     
  10. I'm having back and front focus issues with various lenses on my d90. I do have all of the same issues with my d300 or d700, but I was able to fine tune them with those cameras. Specifically I had issues on all these cameras with the 85/1.8D and the 50/1.4D.
    To the person who said that lenses are always the culprit I say: b***s**t. I've gotten the two lenses above to work properly--in fact insanely well. Just needed to set adjustments in the body.
    Here's where things get interesting: I tried several d90 bodies and they all had trouble with those two lenses. But the new 50/1.4G and 35/1.8G work just like they're supposed to. You could say it's just slop in the screw drive mechanism...but if that were the case, why would I be able to fix it on the D300 and D700?
    This would be easily fixable if I could perform the same calibration on the d90 that I can with my other cameras.
    You might say "well that's just a feature you lose on the lower end cameras. Buy a more expensive camera and it all just works".
    Well, I want a light quiet body. And the d90 has a screw drive to use those older lenses that I love so much. If it has the capability of focusing screw drive lenses, shouldn't they focus properly out of the box?
    Here's my theory. The issues I've seen are so consistent that they have to be intentional. Why would Nikon do that? So that you will try the old lenses, think they're crap, and instead buy new ones. Planned, retroactive obsolescence.
    Well eff dat.
    It's going back to Nikon with a list of EVERY chipped AF lens for calibration.
    In closing, yes, the D90 has definite consistent focus issues with particular lenses. Those lenses are perfectly fine. It's the body, not the lenses.
     
  11. Oh, also I've noticed a discrepancy between the center cross point and the outer ten points. The outer ten are consistently better, but still not quite hitting the proper plane.
     

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