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17-55DX owners -- a little help, please

Discussion in 'General Technical Discussion' started by PhilY, Apr 26, 2005.

  1. Using my D70, I have been a little disappointed with sharpness when shooting landscapes wide (17-20MM) unless I was stopped down to normal the subject range of F11-F16. I decided to do a little testing from tripod to see if I could figure out what was going on and I made an interesting discovery.

    It's a pretty simple check. Set your lens to 17MM and using the center focus bracket in single AF and aperture pri, focus on a far target (say, over 100ft) without taking a shot. After the focus, take a look at the lens focus scale and let me know the reading.

    Mine (and now several on DPR) tends to focus at 8-10ft any time the target is over 40 feet or so and the shot is OOF. I can manually focus at infinity and the target is sharp as a tack. At first I thought I had a lens problem but now am beginning to think it's a D70 focus issue when too much "stuff" is in the bracket and the sensor is seeing it as "close". As I said, this si with the D70 but you "big D" guys may want to check as well.

    Thanks for the help!

  2. dkapp


    Mar 18, 2005
    San Francisco

    Just read you test again, and my first shots were with it at 55mm.

    I re-shot with the lens at 17mm & the lens focused between 10' & infinity on both cameras and the subject was over 100' away. Bringing them into my computer, they are in focus. I shot these at f/2.8.

    I also switched the camera to MF, and was able to move the lens closer to infinity & the focus lock indicator still stayed on. I may have to do some more testing & compare the two side by side. I may be able to get around to it this afternoon.

  3. MontyDog


    Jan 30, 2005
    #1064 - You have an error in your SQL syntax;
  4. Thanks for the reply, Dave. I forget what cam you have -- D2H? I have quite a thread going on DPR and, as it turns out, the vast majority are having the exact same problem I am. Go figure! I would appreciate knowing the results if you do any more tests.

  5. dkapp


    Mar 18, 2005
    San Francisco
    I shoot with the d70 & d2h. I should say that my D70 just came back from Nikon last week after replacing the shutter, adjusting AF and a laundry list of other fixes. I'm not sure how my D70 would have done before the adjustments. It does seem to perform correctly now.

    I just dropped my sister off at the airport after a nice weekend visit, and need to catch up on some work. I hope to get outside & snap a few shots in a couple of hours.

  6. I just checked my 17-55mm out on my D2H and it zips smartly to the center of the infinity symbol.
  7. obelix


    Mar 17, 2005
    Fremont, CA, USA

    I read your threads with great interest. Please keep us posted. I will be very interested in knowing what you find.

    Good luck.

  8. Thanks for the check, Gordon. It's beginning to look like the "focus adjustment" Nikon did on my cam's last trip was a focus maladjustment. :) 

    'Tis strange, though, many people are experiencing the same.

  9. Thanks, Anand -- will do. I have been in an email and phone conversation with the Nikon Tech guys most of the day. They requested sample images and I sent them this afternoon. I pointed them to the thread I started at DRP and, in effect, they said, "holy shat" after they saw how many cams are doing the same. Well, they didn't exactly say THAT but you know what I mean. :) 

  10. obelix


    Mar 17, 2005
    Fremont, CA, USA
    :) . Never under-estimate the power of DPR, I guess.
  11. Using a D2X, distant objects are in focus between the 10ft mark and infinity. Worrying, although I need to test the actual images produced.
  12. dkapp


    Mar 18, 2005
    San Francisco
    My D70 & D2H behave the same way & the images were fine. When I set the lens to infinity, they were horribly out of focus. It was obvious even in the VF.

    I guess the distance markings of the lens are off at 17mm, but fine once you move through the range. I'm not worried about it. It works perfectly. I've got 4.5 years left on warranty, so I'll wait until its really broken before I send my baby away.

  13. Phil,

    I think mine is doing this too. Here are 100% crops, on the new (to me) D2H, first in AF mode (center reticle, single area, f/2.8 at 17mm), followed by manual focus with the focus mark half over the first circle of infinity.

    These are straight from the NEF conversion with normal sharpening in-camera, not altered afterwards. The AF shot was aimed at the gate lock (1/3 right of the picture), from at least 30ft away: remember this is 100% crop.

    Subscribe to see EXIF info for this image (if available)

    Subscribe to see EXIF info for this image (if available)

    (ignore the difference in exposure: I must have locked it, on a different spot.)

    By the way, this only happens with the 3 sensors in the middle row, and not the vertical ones.

    You probably remember what I was worried about with the D70 at infinity before: I think it was a combination of this problem on the 17-55 (all where at wide angle) and a few hazy shots taken with the 24-120.

    Has Nikon gotten back to you about this? Are you sending your lens in for service?
  14. Many, many zooms "focus past infinity" - by design

    I've read about this in two or three places before. Autofocus zooms often have more focusing range around the infinity mark than manual focus zooms. Elements in the lens change with temperatures, the old high school physics of expansion and contraction due to temperatures. It may not seem like much, but when you're dealing with 10 or more elements, and several tubes of different materials... it IS significant.

    The result is that things at infinity often go into focus before the infinity marker hits your "distance is here" notch, and often the lens will continue on past infinity. It's not a fault, but it is weird if you've been around long enough to remember lenses that go "clunk" into place at infinity. Non-zooms usually don't have as much of this built in, if any. And the bigger the zoom range, the more you'll find. My 24-120VR and 80-400VR have a lot more of this play than my 80-200AFS.

    I've experienced times when I noticed that the camera was placing infinity at a different place than usual - once in Sri Lanka on the coastal game preserve around 3pm when I was drinking a litre bottle of water every hour and still losing ground. Not sure what the temp was, but HOT will suffice. And the other time I noticed was on a scary trip down from Mt St Helens in a blizzard when all my lenses were grinding to a halt because the cold was solidifying the lubricants. COLD.

    The other issue with autofocus lenses that you should remember is that autofocus works on detection of contrast differences, so at the point that the lens is zipping around and detects a sudden pop in contrast, it stops. Now, given DOF for any lens, there's obviously a RANGE of areas where the lens could stop. It doesn't stop in the center of the focus range, it stops when it detects it. That means that sometimes ALL of your DOF is behind the focus point the lens selected; sometimes all in front. Sometimes it comes to rest just past because of momentum and then your DOF is distributed. That means that sometimes you'll think the lens is not focusing properly, but it is - it's just not autofocusing the way YOU want it to. (Hey, it's a dumb machine.) It's more pronounced with longer lenses and less DOF; having shot with a number of 80-400VRs that people told me "didn't focus correctly" and finding that in my hands they DID focus just fine, I can attest to this phenomenon. (I learned that mine focused correctly from someone else who gave me the demo...and have been passing it along.)

    How that two or three inches of depth of field gets distributed can make the 80-400VR AND/OR the photographer look pretty awful if you don't pay attention. That's why the AF lenses allow you to touch focus the last bit without them second guessing you. It's a good habit to learn.

    And sometimes you get a bad camera, or a bad lens. But as a doctor friend of mine told me once about diagnoses, if you hear hoofbeats, odds are you should start by assuming it's a horse coming, not a zebra, unless you're on the veldt... In my experience, bad lenses and bad cameras are a really small problem. (Maybe I've just been lucky.)
  15. Flew


    Jan 25, 2005
    Excellent analysis Ed.


  16. Do I have a problem?

    Good morning, Philippe

    Sorry for my delay in reply. I have been frustrated beyond description by this issue and have been too busy grinding my teeth down to reply. I apologize.

    Yes, Nikon finally got around to responding. Their lack of response has been part of my frustration and I will never again contact Level 3 Support. It went something like this:

    Customer Service suggested I give them a call with the issue. I did so and promptly got an email requesting info and samples which I sent right away.

    Wait some days.

    Give them a call and ask what's going on. They stated the guy handling my issue left the office on a business trip THE DAY HE SENT HIS REQUEST TO ME and wouldn't be back for another week. Got an email from a different guy requesting info and samples and I promptly sent them in.

    Wait some days.

    Give them a call and ask what's going on. The guy now handling my issue is too busy to talk to me but will send me an email. He does so the next day and it says, "Got your samples -- is your camera set right?". I freak out and threaten to molest my neighbor's wife but calm down and reply to his ******* question.

    Wait some days -- five, to be exact this time.

    Was in the process of calling them again when my email notification popped up. The email said, "I think something is wrong with your camera so you need to send it in -- send your lens, too". I go off looking for my neighbor's wife again. (if you could see her, you would understand why that's an option) hehheh

    So, yeah -- my cam and lens is back at Melville as of yesterday.

    Let me see if I can figure out how to post an image here to demo my problem. Keep in mind my D70 and 17-55 focused PERFECTLY before they "adjusted" my auto-focus. These images are test shots *only* with no artistic intent or merit intended. Shots are at F2.8, 17MM, and from a solid tripod timer released and have no post processing except resize for the first one and 100% crops for the other two. In-cam sharpening set to "Off"

    Here is the full frame resized to set the scene for you. In each shot, the little pavilion was the focus target using the center sensor.

    Subscribe to see EXIF info for this image (if available)

    Here is the 100% crop from the auto-focused image.

    View attachment 7794

    Here is the 100% crop from the image I manually focused to infinity -- what the camera *should* have done.

    View attachment 7795

    Remember, this cam/lens focused perfectly before. Do you think I have a problem now? :lol:

  17. Re: Many, many zooms "focus past infinity" - by de


    Thank you for your detailed reply. I appreciate your help. Even though all my previous SLR experience has been split ring/split prism type manual focus, I am well aware of the behavior of zooms and the infinity mark. The focus point will be different even on the same lens from wide to full zoom and can vary according to temp. This cam/lens combo auto-focused perfectly before Nikon adjusted it and, since the problem reared its ugly head, I have tested literally 100s of different targets at various distances using all sensors after my original post. My engineer side demanded I perform critical tests. I will ask you trust me when I say there *is* a problem this time. :wink:

  18. There is definitely a problem with this lens and my D70. Same exact behavior as Phil's.

    I cannot reproduce this problem using my D2X. Seems to me it is something about the D70's autofocus.

    I never knew this to work correctly on my D70, then again I haven't really used the wide end of this lens very much.
  19. There's always a chance of bad lenses

    And I understand your threatening your neighbor's wife given that Nikon adjusted your camera and it produced the problem. I must have missed that in the original post.

    I have not had great experiences with Melville - not that they screwed up work, but they're not very good at reporting processes. Ride them close to make sure that you know where your lens is in the process. And in my case, after fixing my lens mount, they gave me a complimentary sensor cleaning - which meant that my camera was returned with enormous amounts of what looked like polar fleece all over the sensor. Took me five swabs to get it all off. Good thing it was "complimentary."
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