Banding on long exposures: lens or camera?

Started Jul 15, 2013 | Discussions thread
Anders W
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Re: Banding on long exposures: lens or camera?
In reply to Ncedra, Jul 15, 2013

Ncedra wrote:

Hello all.

I was at a festvial this weekend and took some long exposures with my OMD in Live Bulb mode at base ISO (200) and with a small and very flimsy tripod. I used the 20mm/1.7 lens, which is known for banding issues at high ISOs. On the computer I saw that the long exposures show quite some banding in the sky, which gets worse when PostProduction is not applied very carefully. The live bulb mode als introduces some noise as I have read.

Do you know if this problem is due to the lens or due to the live bulb mode?

The kind of banding you show here is due to the lens and the camera combined but has in all likelihood nothing to do with live time/bulb, nor with the long exposure per se. The 20/1.7 is prone to cause banding but only on the E-M5 and other cameras with the same sensor (including the GH3 according to the GH3 manual). So both the lens and the camera is to blame.

The most likely cause is some kind of electrical interference between the circuitry of the lens and the circuitry of the camera (with the 20/1.7 being an unusually strong source of such interference and cameras with the latest sensor unusually sensitive to it). As Bob pointed out, it may help to "warm up" the 20/1.7 a bit before use (give it a few AF cycles) but the exact nature of the problem is hard to nail and I am still not sure this always helps with my own copies of lens and camera, let alone that of others.

Note also that the 20/1.7 is not the only lens that can give rise to banding with the latest sensor generation. I have seen examples of it with other lenses too but the 20/1.7 is in all likelihood the worst "sinner" in this regard.

Live time/bulb will generate slightly more read noise than would the same exposure if shot without the live feature but the difference is fairly small. Further, there is no evidence that I am aware that live time/bulb generates pattern noise (banding), just that the overall noise level increases slightly. More info on the ins and outs live time/bulb here if you are interested:

http://www.dpreview.com/forums/post/50399103

If it is the camera, is there a work around? Maybe less captures during live bulb mode?

It was my first try of long exposures with this camera, so I haven't tried other lenses. The pictures were taken in RAW and I tried to be carefully with PP, so the banding is not too prominent on websized pictures. If you look closely, you can see it in the skies on the left and right side.

Wetterleuchten Festival

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