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Tamron 28-75 2.8 Question

Discussion in 'Lens Lust' started by smodak, Jun 25, 2007.

  1. smodak

    smodak

    Jun 11, 2007
    Franklin MA US
    I just bought a tammy 28-75 used off of ebay. the seller is great and would take the lens back if I am not happy. I am not a test chart shooter (not now anyways) but I am noticing some weird backfocus issues on the lens (so far tried on the D1H only, I will try on D200 and D200 later). This is no sceintific test anyway but just some quick snaps on a new lens...(please do not look at my wonderful composition and subject choice :wink:) 

    The lens seems to backfocus only at 75mm open wide unless I focus on a flat subject). Or is it a deapth of field control?
    This may as well be me but your input is really appreciated.

    All 100% crop, no in camera sharpening, an USM of 50-5-4 is applied in NX (to null the effect of the AA filter), no tipod used. Exif is in the oimages.

    f2.8
    http://i109.photobucket.com/albums/n43/smodak/DSC_0120.jpg
    http://i109.photobucket.com/albums/n43/smodak/DSC_0104.jpg
    http://i109.photobucket.com/albums/n43/smodak/DSC_0092.jpg

    f4
    http://i109.photobucket.com/albums/n43/smodak/DSC_0105.jpg
    http://i109.photobucket.com/albums/n43/smodak/DSC_0099.jpg

    Am I imagining things?
     
  2. smodak

    smodak

    Jun 11, 2007
    Franklin MA US
    Pics..

    f2.8


    DSC_0120.
    NIKON D1H    ---    75mm    f/2.8    1/80s   

    DSC_0104.
    NIKON D1H    ---    75mm    f/2.8    1/1600s   

    DSC_0092.
    NIKON D1H    ---    75mm    f/2.8    1/320s   


    f4
    DSC_0105.
    NIKON D1H    ---    75mm    f/4.0    1/1000s   

    DSC_0099.
    NIKON D1H    ---    75mm    f/4.0    1/125s   
     
  3. I don't think you are imagining it. The difference between the 2.8 and 4.0 is pretty drastic. (This assumes you were focusing on the exact same spot.)

    Craig


     
  4. smodak

    smodak

    Jun 11, 2007
    Franklin MA US
    Thanks Craig. Yes the focus was same...but it is unbelievebable that the difference is so drastic between 2.8 and 4. What is the point buying a 2.8 lens then?

    Also if you see the railing shot at 2.8, you would see the stump on the back (to which the railing is attached) has the focus...is this not a typical example of back focus?
     
  5. I think you're right. The focus is on the stump on the back. How were the reviews on this lens? And, did the guy say why he was selling? My biggest fear when buying on Ebay is that people are selling because the lens has issues. I just bought a Tamron (labeled Promaster) 11-18 used, but I met up with the guy and tried it out first.

    I would probably send yours back, unless someone with more experience can gives you better advice.

    Craig
     
  6. smodak

    smodak

    Jun 11, 2007
    Franklin MA US
    The seller did not notice it but he is a very good seller. He said that there was a 7 day full-refund warranty on the lens. After I told him about the front focussing, he extended the warranty for a month and said he wants me to be fully happy with the lens....
     
  7. smodak

    smodak

    Jun 11, 2007
    Franklin MA US
    False Alarm

    The lens works fine on my D200

    100% crop
    DSC_0019.
    NIKON D200    ---    75mm    f/2.8    1/1250s    ISO 200



    DSC_0014.
    NIKON D200    ---    75mm    f/2.8    1/125s    ISO 200
     
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