Banding on long exposures: lens or camera?

Started Jul 15, 2013 | Discussions
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Ncedra Forum Member • Posts: 73
Banding on long exposures: lens or camera?
1

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?

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

s_grins
s_grins Forum Pro • Posts: 11,024
Re: Banding on long exposures: lens or camera?

I think this is a sensor + over PP that transferred a night into a day.

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Ncedra OP Forum Member • Posts: 73
Re: Banding on long exposures: lens or camera?

The problem is I didn't do a lot of PP: some white balance and only slight changes to exposure and contrast, because I saw that this just emphasises the banding. What turned the night into a day is the 30s exposure and the light pollution in the Innvalley.

s_grins
s_grins Forum Pro • Posts: 11,024
Re: Banding on long exposures: lens or camera?

Ncedra wrote:

The problem is I didn't do a lot of PP: some white balance and only slight changes to exposure and contrast, because I saw that this just emphasises the banding. What turned the night into a day is the 30s exposure and the light pollution in the Innvalley.

Did you try to reduce exposure during PP (one stop maybe)?

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Bob Tullis
Bob Tullis Forum Pro • Posts: 31,946
Re: Banding on long exposures: lens or camera?

Nice photo.

The 20/1.7 can produce banding, particularly. Anders has found out if one tries to AF the lens for a few seconds before executing the shot the banding may be avoided.

Banding like that may be tamed with a NR app like Dfine (I don't know if other NR apps as of late also have a banding correction feature).

Live Time/Bulb modes can tend to be a little noisier than the standard long exposure, but that's a different matter.

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Ncedra OP Forum Member • Posts: 73
Re: Banding on long exposures: lens or camera?

Thanks for your input! Tonight I will give the pic a PP rerun with lower exposure settings and look for some NR software.

s_grins
s_grins Forum Pro • Posts: 11,024
Re: Banding on long exposures: lens or camera?

Ncedra wrote:

Thanks for your input! Tonight I will give the pic a PP rerun with lower exposure settings and look for some NR software.

This is my take of your photo:

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Ncedra OP Forum Member • Posts: 73
Re: Banding on long exposures: lens or camera?

I don't manage to open it in a bigger size, but judging from the image in the thread you are right, there is more night in your pic. Did you just reduce general exposure? Or did you do some more refined PP-magic? I'd like to keep the outlines of the tents in the shadows visible and the bright trace of the headlamp to pop out, so I have to mask these areas for exposure reduction.

s_grins
s_grins Forum Pro • Posts: 11,024
Re: Banding on long exposures: lens or camera?

Ncedra wrote:

I don't manage to open it in a bigger size, but judging from the image in the thread you are right, there is more night in your pic. Did you just reduce general exposure? Or did you do some more refined PP-magic? I'd like to keep the outlines of the tents in the shadows visible and the bright trace of the headlamp to pop out, so I have to mask these areas for exposure reduction.

I did reduce general exposure. Also I've applied a little of blur to reduce noise. All this took not more than 15 sec. You can do it better if you can spend 2 minutes

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Ncedra OP Forum Member • Posts: 73
Re: Banding on long exposures: lens or camera?

Thanks! I will give it a go tonight!

Anders W Forum Pro • Posts: 21,466
Re: Banding on long exposures: lens or camera?
1

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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Ncedra OP Forum Member • Posts: 73
Re: Banding on long exposures: lens or camera?

Thanks for your extensive reply!

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.

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.

inasir1971
inasir1971 Veteran Member • Posts: 3,462
Re: Banding on long exposures: lens or camera?

Did you have IBIS on? For long exposures remember to switch off IBIS/IS.

As someone above suggested, exposing to the right and dropping the exposure in post will help with any banding...

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Anders W Forum Pro • Posts: 21,466
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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Ncedra OP Forum Member • Posts: 73
Re: Banding on long exposures: lens or camera?

This is how it looks now. The banding is a lot better. I think the Lightroom import settings went a bit crazy.  Corrected that and reduced the exposure. Thank you for your input!

I accidentally left the IBIS on, but I corrected this for the following pictures. I cannot see a difference in sharpness. The tripod was very small and shaky, so all pictures are not supersharp at greater magnification.

s_grins
s_grins Forum Pro • Posts: 11,024
Re: Banding on long exposures: lens or camera?

Good to know. Thanks for informing.

S.

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