Pana 7-14 issue: field curvature?

Discussion in 'Native Lenses' started by mftlandscaper, Apr 25, 2013.

  1. mftlandscaper

    mftlandscaper Mu-43 Regular

    Feb 6, 2013

    I am using the Pana 7-14mm lens on my GX1 and GH2 cameras. I find the image quality superb over most of the frame (better to my eyes than my Oly 12mm). However, I am seeing one recurring issue that is driving me crazy.

    Typically I shoot wide-angle landscapes with a significant amount of foreground included (usually from a tripod). The closest foreground elements are usually 1-2m from the camera. In this case, if I focus 'normally' (i.e. on the main subject, or roughly 1/3 of the way into the frame) the bottom corners of the image are noticeably out of focus, whereas the bottom edge is pin sharp. If I manually focus the lens on the closest part of the foreground (right at the bottom of the frame) this effect is reduced drastically and the corners look quite good. This seems to happen at all focal lengths, even when stopped down to f/8 (where the depth of field should be enormous). The corner blurring is noticeable in prints (although admittedly I am fussy and I'm sure most people wouldn't notice).

    I suspect it is a case of strong field curvature at close range. I realise this is inherent with most wide zooms, but it has spoiled a lot of my images and I haven't seen this issue reported by any other users. I don't see this effect with the Oly 12mm lens - the focus field seems totally flat at close range with that lens. If I photograph more distant subjects with the 7-14mm (without very close foreground) then the images seem fine.

    Does anyone else notice this? Or have I got a dud? The lens has been like it since new (6 months ago). Everything else about the lens seems fine - it's razor sharp (when in focus), CA is extremely well-controlled, and it appears to be well-centred. I know it's capable of incredible results, but I can't stand having to manually focus on the immediate foreground for every shot to get the sharpest results.

    Can anyone confirm whether or not this field curvature at close range is normal behaviour?

  2. mattia

    mattia Mu-43 Hall of Famer

    May 3, 2012
    The Netherlands
    Mane try focussing at the hyper focal distance, which is less than a meter from the front of the lens at f8?