After I wrote about the Voigtländer optical viewfinder or OVF on the Panasonic GF1 yesterday, our friend Edward Taylor, who has written several reviews of small cameras for us, wrote a comment to the effect that his Lumix 20mm ƒ/1.7 lens was giving him a lot of trouble with flare. "I have never had a lens that suffers as much from flares or backlighting or even light coming around a corner. Contrast is ruined," Ed wrote. When I emailed him and asked him to clarify, he said, "I love the lens, but if a subject is backlit or if there is a bright light source even outside the frame of the photo, contrast is lost and the photo looks washed out. It almost looks like the lens is fogged and a lot of detail is lost so it can’t be fixed in post. It is not an exposure problem as no amount of bracketing will correct it. I have noticed this since I got the camera, and I use it virtually every day."
That didn't sound right to me at all, and I know Ed knows what he's talking about, so I wandered around this morning and snapped off a few quick "flare and glare" tests to help him troubleshoot. (For the terminologically fastidious, "flare" refers to ghosts and other visible artifacts caused by spurious reflections inside the lens or camera; overall hazing or loss of contrast is technically "veiling glare." Hence "flare and glare.") All these shots except the last one are default JPEGs right out of the camera, resized and converted to sRGB for the web but otherwise untouched.
Nine a.m. sunlight on a dirty window, at ƒ/2.8. Not the worst case for backlighting, maybe, but I'm not seeing any problems.
A "100-watt equivalent" compact fluorescent, shot handheld with –3 stops of exposure compensation, with the lens wide open at ƒ/1.7. The picture looks quite a bit darker than the visual impression. No flare except for very slight haloing around the fluorescent coil, which is to be expected. The contrast in the pull chains is fine.
A picture with the sun in the frame, but placed off-center—it's at the edge of the trees but not obscured by branches. This shot was exposed (maybe even a little overexposed) for the foliage (ƒ/2.8). There's a little flare here, finally, but you can see it better...
...in this shot, the same scene exposed (maybe even a little underexposed) for the sky (ƒ/7.1). This is the only flare I was able to get this morning—that purple blob just to the left of the orb of the sun is a so-called "ghost." But the branches show good detail even very near the sun; that deteriorating contrail wasn't visible to the naked eye, as it was lost in the brightness of the sun. Also, if I goose the contrast and brightness a bit...
...you can even see a little detail in the foliage quite close to the sun.
That all looks like extremely good flare 'n' glare performance from the Lumix 20mm to me. In fact, it's one of the standout qualities of this fine little lens, in my opinion. I never worry about flare when I shoot with it.
When I sent him these test shots, Ed realized immediately that there is something definitely wrong with his copy of the lens. He's going to send his back to Panasonic.
If you're having flare 'n' glare trouble with the Panasonic Lumix 20mm ƒ/1.7, you shouldn't be. And if you read out in the wilds of the internet of people having such trouble, you should clue 'em in that their results are not what they have a right to expect.
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Original contents copyright 2010 by Michael C. Johnston and/or the bylined author. All Rights Reserved.