How to find out if lens is too soft/bad copy ???

Discussion in 'Photography Beginners' Forum' started by YoungRebel, Apr 13, 2008.

  1. YoungRebel

    YoungRebel TPF Noob!

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    Hey guys...

    In 2007 I bought the Canon EF 24-70 f/2.8 L.
    As you know it's not a cheap one and so I am a little worried about the quality that it produces...

    I researched online and so many shots from others (same lens) looked just way sharper at almost all f/stops as in the different focal-lenghts...

    I'd like to know if there is a "best way to" to test a lens on softness!?

    To just give you an example:
    70mm - 1/400 - f/5 - ISO200

    100% crop


    I updated from a canon 28-105 $300 lens and I honestly gotta say that when I look at pictures like this I regret that I bought the L lens... :(

    That's why I posted this thread, maybe it's "just" a bad copy and I should send it in for recalibration....

    Thanks for your time!

    I appreciate every answer :)
     
    Last edited: Sep 11, 2009
  2. KhronoS

    KhronoS TPF Noob!

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    Well if you want to test the lens, try using an object to take photos of, then a tripod, and double check the focus... might be a focus problem... try testing with a focus chart... :)
     
  3. evo5gsr

    evo5gsr TPF Noob!

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    I'm curious, how often do people get bad copies?
     
  4. JerryPH

    JerryPH No longer a newbie, moving up!

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    With Canon? Quite rare. With Sigma? It was a lot more common a year ago than it is now, and it was specific to only a few models (first and second generations of the 18-50mm, 30mm and a few others). It was not a softness issue, it was a front/back focus issue.

    95% of the time, sharpness issues are related to poor shooting technique, poor understanding of the basics, poor post processing techniques or a combination of the three.

    For the lens front/back focusing issues, you can google focus chart and use that. It's results are good ONLY if you use it following the instructions 100%.

    In your case, Patrick, I am pretty confident that its a 75% post processing and 25% shooting technique issue and not the lens. If your picture had more EXIF camera related info, I could tell you a touch more.
     
  5. Garbz

    Garbz No longer a newbie, moving up!

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    With every company it's quite rare. Some people will sware black and blue various things do this or that but they just forget basic laws of diffraction or it's outright user error that the image is backfocused.
     
  6. soylentgreen

    soylentgreen TPF Noob!

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    Do a search for lens sharpness chart. Someone posted one a couple of months back. Print it out and follow the instructions. I used it for my 70-200 f/2.8L IS because I thought it was "soft". Way wrong on my part. Lens is ridiculously sharp. It was me. :mrgreen:
     
  7. MX962

    MX962 TPF Noob!

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    http://focustestchart.com/chart.html

    Here is the focus test page it has a mixed review but may come in handy for you, also a simple ruler laid out flat and camera at a 45 degree angle works pretty well also .......Be sure to use alot of light ! and dont under expose its easier to see the results;)
     
  8. CWA_JGEISINGER

    CWA_JGEISINGER TPF Noob!

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    How are you planning on making the image more sharp in post .....

    The only way I know is to use smart sharpen or something like that in PS and with that you can only do so much before the image starts to distort.


    Is there another way?
     
  9. JerryPH

    JerryPH No longer a newbie, moving up!

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    There are several ways.
    - The basic sharpen in PS
    - The smart sharpen in PS
    - NIK software Pro sharpener
    - In camera sharpening
    - Adobe Camera RAW sharpener

    I use three methods, dpending on the results I want:
    - Camera RAW sharpening
    - NIK Sharpener Pro v.2.0
    - Smart Sharpening in Photoshop

    Like everything else in life, too much of anything is not good. It will not correct for a picture blured by bad technique. It will sharpen a well focused picture for a nice improvement in crispness.
     
  10. RyanLilly

    RyanLilly No longer a newbie, moving up!

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    Plus, if you shoot raw, there is no in-camera sharpening applied sharpening(among other adjustments) is required in post.
     
  11. YoungRebel

    YoungRebel TPF Noob!

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    Thanks guys! I will totally try it out with that chart....

    Another question:
    Under the same circumstances, just changing aperture-settings, f/4-f/5 is sharpest, everything else looks softer, even when shooting with tripod.
    Isn't f/22 supposed to create an overall sharper image than f/4 ? Or at least the same sharpness on the focused spot? - looks way softer with mine....
     
  12. soylentgreen

    soylentgreen TPF Noob!

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    Not so. Almost all lenses will start to degrade past f/11 or so. With the higher quality of L lenses, they retain optimum performance from wide-open to 1-2 stops down. That's the premium you pay for such a lens. Your 24-70 should perform just as well at f/2.8 as f/4-5.6. My 70-200 is only slightly sharper at f/4 or f/5.6. Only major diference in the DOF. My 400 practically stays at f/2.8. I only stop down when the shutterspeed is too high for the camera to cope or the 1.4x TC is attached.
     

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