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Sharpest f stops on 20mm?

Discussion in 'Panasonic Cameras' started by Jamus, Apr 24, 2010.

  1. Jamus

    Jamus Mu-43 Regular

    131
    Apr 18, 2010
    Peter Jamus
    Just curious, I know some lenses have 'sweet spots', so I was wondering what f stops are particularly sharp on the 20mm f1.7.
    Thanks.
    :redface:
     
  2. Jonas B

    Jonas B Guest

    91
    Apr 23, 2010
    Gothenburg, Sweden
    I would say the lens is sharp enough from f/1.7-f/5.6. Maybe the sweet spot is around f/3.5 but then you are chasing that little extra which in this case is such a small extra that it doesn't matter. For real good center sharpness stick between f/2 and f/5.6.

    Or, go play with the lens test widget at DPR here.

    my cents,

    /Jonas
     
  3. vincechu

    vincechu Mu-43 Regular

    I tend to use it roughly arround f/3 where it seems sharpest to me but wide opens pretty sharp too - but its such a great lens I find i don't have to worry too much about sharpness - unless u're stopping down massively that is ;-)
     
  4. PeterB666

    PeterB666 Mu-43 Top Veteran

    780
    Jan 14, 2010
    Tura Beach, Australia
    Peter
    Probably around f/4 to f/5.6. Most lenses are pretty weak full-open and getting beyond f/8 you start to get the impact of defraction caused by the small aperture.

    There are a number of reviews on the internet showing graphs of sharpness of this lens so if you want a more definitive answer, try Googling 'Panasonic 20mm reivew' or similar.
     
  5. Iansky

    Iansky Mu-43 Hall of Famer

    Dec 26, 2009
    The Cotswolds, UK
    Traditionally and as I was taught when studying, the optimum aperture for sharpness on any lens is 2 full stops down from wide open.

    The 20mm is an outstanding lens that if used carefully can produce some superb images with a great bokeh, the lens is very sharp wide open so much so that it is often just a case of deciding on depth of field requirements!
     
  6. kwaphoto

    kwaphoto Mu-43 Regular

    55
    Jun 4, 2010
    Colorado, USA
    I have found that f/2 yields a great results but I don't hesitate to use it wide open either. Otherwise, I just adjust based on the desired DOF rather than "sharpness" or a sweet spot. I shoot my images for the image sake and not the lens' desires :2thumbs:
     
  7. Grant

    Grant Mu-43 Veteran

    Traditionally the teaching is that tie sweet spot is in the mid point of the f/range. From all the test I have read Panasonic has bumped there sweet spot closer to the wide side of the lens. My 20 mm is very good wide open although there is a softening further off axes, still not very bad. At 2.8 it seems to generally behave very well. My 20 mm is good even at f/16 but not perfect there. On the other hand my 14-45mm is almost too soft at f/16 although still usable.
     
  8. Jamus

    Jamus Mu-43 Regular

    131
    Apr 18, 2010
    Peter Jamus
    Thanks, Bill!
     
  9. BillN

    BillN Mu-43 All-Pro

    Jan 19, 2010
    SW France
    I always thought - use f8

    the 20mm only needs around f3.5 - f4.5 ...... so it would seem
     
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