Banding with the Panasonic 20/1.7 Lens

Started Jul 27, 2015 | Discussions thread
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Egregius V
Egregius V Regular Member • Posts: 253
New test results, E-M5 II and 20mm f/1.7 II
1

OK, I just completed a set of tests of the 20mm lens on my E-M5 II. Here are the specifics and my findings.

Test parameters: Aperture priority, ISO6400, exposure ranging from 0EV to -7EV to compensate for blown highlights without crushing any shadows. Shutter automatic (ranging from very fast at f/1.7 to 1/80s at f/8).

Variables: four apertures (f/1.7, 2.8, 5.6, 8.0), IBIS=1 or 0, Flicker reduction=off/Auto/60Hz, shutter mode (single mechanical, 0s antishock, single silent), presence or absence of artificial light (room chandelier, an LCD clock, and a power LED located outside the camera's field of view but still in front of the camera).

Results:

1. Effect of flicker reduction mode with any lighting, shutter mode, etc.: NONE. The problem is no longer reproducible. (What changed since my last test? Only two things, I think: a new SD card and a firmware upgrade to v1.2.)

2. Effect of aperture on noise pattern: At f/1.7, the banding is not really perceptible when pixel-peeping; however, it is somewhat visible when the image is scaled down. Banding becomes more visible, consisting of thinner and more dense horizontal bands as aperture value increases (and vignetting decreases).

3. Effect of IBIS: none that I can see.

4. Effect of time elapsed (warming up the lens): none that I found so far.

5. Effect of ambient light: NONE. Banded noise pattern was visible in brightly-reflected room light as well as in shadows, as long as the high-contrast test scene was used. What does this suggest? (A) While banding is not visible in the highlights, it is also not limited to dark shadows. (B) Banding occurs regardless of exposure, provided that the scene has high contrast.

5. Effect of shutter mode: (A) Mechanical shutter ALWAYS produced banding in my tests. (B) My limited test of the 0s antishock mode (owing to fast shutter speeds with wider apertures) indicates that it makes little to no difference. (C) Electronic shutter yields no noise-pattern banding that I can see.

6. (EDITED AFTER POSTING) Did the electronic shutter show any banding at all? YES, the broad bands imparted by the flicker of artificial light. I thought I saw a second kind that also occurred in the other shutter modes, but it appears now to be nothing of significance. Here's what I'm referring to. In some of my tests, the lower corner of a picture frame cast a shadow on the wall, which in the JPEG and RAW images seemed to extend horizontally as a faint dark stripe halfway to the window nearby. Some other details also extended in this way. A minor, barely visible aberration in the noise pattern that I can't attribute to anything. It went away in subsequent tests in which I varied exposure, metering, ISO, and aperture while more strictly controlling the ambient light.

I'll post some samples to Flickr when I have time. Right now, I have to get back to work.

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Olympus E-M5 II Panasonic Lumix DMC-GX85 Olympus M.Zuiko Digital ED 9-18mm F4.0-5.6 Panasonic Leica Summilux DG 25mm F1.4 Olympus M.Zuiko Digital ED 40-150mm 1:4-5.6 R +11 more
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