D300s and inconsistent focusing.

Discussion in 'Digital Photography' started by wheelhot, Nov 29, 2009.

  1. wheelhot macrumors 68020

    Nov 23, 2007
    Hi, recently I got my D300s + Sigma 18-50 f/2.8 (and a few other accessories). I owned the camera for about 2 weeks and have been testing it in varied conditions. Usually the focusing was top notch and accurate but I recently put the camera to a real test when I use it to photograph a wedding.

    While most of the photos turn out good, I do encounter a problem that are causing me problems during times where I need to get key shots. The focusing seemed off, even-though I double checked to ensure the focusing point is where I wanted (note that I am using single AF point focus)

    I tried stopping down from f/2.8 to f/4 - f/5.6 thinking it was just the lens softness issue at f/2.8 but turns out I was wrong, cause the problem still exists. Some scenes, I asked to have a retake cause of the focusing problem and I still cant get the image to focus properly, so for those photos, I will need to find a solution to make it acceptable.

    Anyone care to help me on this? And I thought it has something to do with Nikon contrast based AF system causing it not to be able to focus accurately on certain scenes, but that's just my guess. I'm not sure why my camera is not being able to focus properly.

    Help pls :rolleyes:
  2. pdxflint macrumors 68020


    Aug 25, 2006
    Oregon coast
    The D300s only uses contrast detect AF in "live view." Anyway, the D300 and D300s have great AF systems, but there are a lot of options of how to set it up for different uses - so it might take a bit of experimenting to find out which settings will yield more 'in focus' keepers for each type of shooting style you use. I know this doesn't help a lot, but I'm still learning myself, how to master the D300 AF system, and the huge customization in the various settings menus that can be assigned in the shooting banks and settings banks, as well as the 'my menu' custom settings. It's practice, practice, practice.

    Here's a snippet from DPReview's review of the D300s discussing the AF:
    Also, here's a link to John Cazolis blog on Nikon gear where he discusses the D300 AF. Actually the entire blog and all the D300 posts, (also applicable to the D300s) especially about how he sets up his camera for different purposes via the shooting and settings banks, make for a good discussion on some various Nikon gear this guy uses. I found it very useful, and more practical than a lot of other "reviews" I've read out there.

    Good luck, and happy shooting!
  3. wheelhot thread starter macrumors 68020

    Nov 23, 2007
    Thanks for the link. It was really useful.

    Right now, I'm thinking of doing a focus check on the lens cause I heard that 3rd party lens is susceptible to focusing problems.
  4. cr2sh macrumors 68030


    May 28, 2002
    I've found that many Sigma lenses that I've owned have had poor focusing performance, especially in low light... I don't buy them anymore because of it.

    Here's a review of that lens noting similar focusing problems.

  5. wheelhot thread starter macrumors 68020

    Nov 23, 2007
    thanks, I've read that too. Too bad I cant find any more similar problems.

    I hope this problem can be fixed though :(

    Damn this sucks, whats the point of getting the lens sharp but cant achieve proper consistent focusing =.=
  6. rhett7660 macrumors G4


    Jan 9, 2008
    Sunny, Southern California
    I was going to comment I would look at the lense first before the camera. I don't have any experience with Sigma lenses thou.
  7. wheelhot thread starter macrumors 68020

    Nov 23, 2007
    Aah, but hmm, I never did any focus test before, anyone care to explain how is the correct technique to measure focusing accuracy (the positioning, aperture settings, does shutter speed make a difference?)? Cause like I said, sometimes it's in focus and some time it's not in focus (but the camera says it's in focus).

    Oh and how far does AF Fine Tune able to...fine tune?
  8. Rondue macrumors regular

    Jul 30, 2008
    Love mine

    I am a new D300s owner and photo n00b I have not had any issues with focusing unless I'm in way to close with my 35mm 1.8 Nikon. I haven't any non nikon lenses though.
  9. wheelhot thread starter macrumors 68020

    Nov 23, 2007
    Good for you, well I remember using my friend Nikkor 24-70 f/2.8 and didn't have any problems with it (well that was my initial test, haven't tried it in real tests) except that it shows more details at higher ISO then my Sigma 18-50! :eek:

    Despite the focusing issue, the D300s performed admirably during the wedding session.

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