400mm f5.6 lens vs 200mm f2.8 lens with 2x teleconverter

Discussion in 'Digital Photography' started by greg, Aug 29, 2004.

  1. greg

    greg Guest

    Hi folks, I have a question about quality.

    I have a Sigma 135-400mm f4.5-5.6 lens (it's 5.6 at over 200mm). I almost
    always only use this to shoot motorsports outdoors.

    I also have a Nikon 80-200mm f2.8 lens.

    I'm considering selling the Sigma lens, and buying a Nikon TC-20E II
    teleconverter (the money should be comparible). This would, effectively,
    turn the Nikon lens to a 160-400mm f5.6 lens for those times I need a longer
    lens. One less heavy lens to schlump around the track, and from a strict
    numbers point of view, it should give me the same lens length and speed as
    the Sigma.

    But I'm wondering about quality or other detrimental effects of using the
    teleconverter. I've never used one before. Will the image sharpness,
    contrast, colour, etc. be comparible to the Sigma lens, or do I pay a cost
    besides the stops?

    Thanks in advance!
    Greg
     
    greg, Aug 29, 2004
    #1
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  2. You have my deepest sympathy.
    You're best to avoid converters with anybody's lens.
     
    Randall Ainsworth, Aug 29, 2004
    #2
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  3. << Will the image sharpness,
    contrast, colour, etc. be comparible to the Sigma lens, or do I pay a cost
    besides the stops? >>

    Greg-

    Of course you pay a cost. The question is whether that cost results in
    acceptable images compared to images from the Sigma lens. It could go either
    way.

    Do you use the Sigma at maximum zoom most of the time? If not, then use of the
    Nikon alone may meet most of your needs and probably produce better images.
    Use of the teleconverter would then be an option.

    Fred
     
    Fred McKenzie, Aug 29, 2004
    #3
  4. greg

    AstroPax Guest

    AstroPax, Aug 29, 2004
    #4
  5. greg

    JPS Guest

    In message <[email protected]>,
    Compare the MTF charts. If the nikon is about half as far as the sigma
    is from the top of the chart, then the combo should be about equally
    sharp. If the MTFs are about the same, then you will go much softer
    with the combo.
    --
     
    JPS, Aug 30, 2004
    #5
  6. greg

    JPS Guest

    In message <>,
    Are those crops of original pixels?

    If not, we can't tell anything about your TC from a shrunk-down image.
    You've then shrunk away most of its effect!
    --
     
    JPS, Aug 30, 2004
    #6
  7. greg

    greg Guest



    Sorry... MTF charts?
     
    greg, Aug 30, 2004
    #7
  8. greg

    AstroPax Guest

    Sure, I know what you mean. Sorry about that.

    Anyway, with a Nikkor VR 70-200mm f/2.8 & TC-14EII @ 240mm, spot
    metered and focused on the eagle's eye.

    Original image is 3008x2000 (2,464KB).

    Here is a 100% crop to 1280x1024, with no additional post-processing
    (260KB):

    http://www.xmission.com/~hound/astropax/temp/Dsc_0263_cropped.jpg

    Original EXIF data:

    http://www.xmission.com/~hound/astropax/temp/Dsc_0263.txt

    -Astro
     
    AstroPax, Aug 30, 2004
    #8
  9. greg

    Aaron Ng Guest

    MTF charts show sharpness at infinite focus. The X-direction scale is radial
    distance (distance from the center), while the Y-direction is pair lines per
    mm. The 3 lines show different contrast levels (highest contrast is the one
    with the highest lines per mm), but I forgot what the dashed line
    represents.

    Here's the chart for the Sigma AF 135-400 f/4.5-5.6 APO Aspherical RF, which
    is the lens I assume you have:
    http://www.photodo.com/pix/lens/mtf/SIAF13540045APO.gif

    And here's the chart for the Nikkor AF 80-200 f/2.8ED (2 ring version):
    http://www.photodo.com/pix/lens/mtf/NIAF8020028D.gif

    I wouldn't say that the Nikkor has 2 times the sharpness of the Sigma, but
    from a weight reduction point of view, the tradeoff might be acceptable if
    you use the TC-20E II (I remember that you have to file off a tab on the
    teleconvertor if you using non-AFS lenses)

    Aaron
     
    Aaron Ng, Aug 30, 2004
    #9
  10. greg

    brian Guest

    These are MTF vs image height plots. Vertical coordinate is contrast,
    not spatial frequency. In these plots there are only small number of
    discrete spatial frequencies shown, each showing how the contrast at
    that spatial frequency varies as a function of image height. In the
    photodo charts the solid and dashed lines represent the sagittal and
    tangential directions, respectively.

    Brian
    www.caldwellphotographic.com
     
    brian, Aug 30, 2004
    #10
  11. greg

    Aaron Ng Guest

    Thanks Brian!
     
    Aaron Ng, Aug 31, 2004
    #11
  12. Get the Simga 70-200 EX, all the 70-200 class lenses rate the same
    optically, and the Sigma is much better built and much less expensive
    than the plastic Nikon...

    http://www.photozone.de/2Equipment/easytxt.htm#Ztelef

    Also the Sigma 1.4X TC has almost no image degradation at all, using
    it is not noticable. The others' TC's degrade image quality
    dramatically, much like the Simga 2X.

    Also, the Sigma 80-400 OS is much sharper than the 70-200 EX at 200mm.
    Forget about any TC besides the Sigma 1.4X EX APO, and don't consider
    the Simga 2X either. Better idea is to get the Sigma 80-400 OS, it
    is significantly sharper than any of the above and a lot stronger. If
    you have to shoot at f/2.8, the Sigma 70-200 EX is the best buy, about
    $800 less than your lower optically rated Nikkor.
     
    George Preddy, Aug 31, 2004
    #12
  13. greg

    Aaron Guest

    Alas, your logic is flawed. He already has the 80-200mm f/2.8. So if he were
    to follow your advice, he would end up spending more than if he purchased
    the TC...
     
    Aaron, Aug 31, 2004
    #13
  14. greg

    Summitar Guest

    Shut up, Preddy.
     
    Summitar, Sep 5, 2004
    #14
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