Banding on long exposures: lens or camera?

Started Jul 15, 2013 | Discussions thread
Anders W Forum Pro • Posts: 21,468
Re: Banding on long exposures: lens or camera?

Ncedra wrote:

Thanks for your extensive reply!

You are welcome.

Before I took this picture, I took some others as well and I had to fight a bit with the focussing because it was so dark, so I think the circuits were warmed up.

Yes, as I said, I am far from sure that the solution I have suggested is a cure-all. In spite of many long threads on the subject with quite a bit of experimentation, I don't think anyone has quite nailed the causal pattern, let alone found a really good remedy yet. It will be interesting to see if the PCB of the new version of the 20/1.7 that has just been announced will look any different from the old. One might hope that Pany has done something to eliminate the ultimate source, most likely a noisy voltage regulator on that PCB.

I read about the high ISO banding of the 20/1.7, but I wasn't aware that it can occur at low ISO as well.

If the banding is there, it is there at any ISO but will show less and less the lower you go (since the ratio between signal and read noise gets larger and larger). As a rule of thumb, I'd say it's rarely visible at ISO 1600 or lower and ISO 3200 may not be much of a problem either. At ISO 6400 and higher, there is a fairly high likelihood that you see it.

Did you push the sky of that ISO 200 shot a bit in post-processing? It looks a bit more noisy in the sky than I'd normally expect an ISO 200 shot to be.

Of course, the fact that you used the live time/bulb feature might contribute slightly to the visibility as well, not because the live exposure feature itself causes the banding but because it increases the noise level slightly, thus making any read noise pattern more visible than it would otherwise be.

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