Colour Banding Issue

[stuck]

...I remember reading a conversation on another Photo Forum around 2009 ??? (ref: EOS 5DMkII) concerning colour banding issues - the gist was the (contaminated) images were taken near a military site and the conversation went into depth on that matter.

I have been looking but can't find the thread - maybe because the indexing of old threads is a bit haywire at the moment. The site is Photo.net.

Anyway - perhaps researching (documented?) effects of RF and other high band interference on EOS DSLRs might spring fruit - we need a resident expert in this area to offer ideas - any takers? Where's Ted?

I am still searching . . .

WW

A Google search on:

effects of RF and other high band interference on EOS DSLRs

returns this page as the first hit:

https://www.photo.net/forums/topic/2...on-movie-sets/

Is that what you are looking for?

Edited to add: The problem image looks like it was taken at Pico do Areeiro, Madeira. I was there in Sept 2022 with my Canon 90D. None of my shots have any banding in them but the 90D is a more recent camera than the 5D mark IV so maybe Canon have fixed the shielding problem alluded to in the photo.net thread??

[DanK]

The combined shutter speed of the six images 104 seconds. I had the camera set to Aperture Priority, with the metering mode as centre weighted average. Shooting height was 1801.6 metres above sea level.

If the issue is LE noise--which at this point I don't believe is the case--the only variables that would matter are the length of time the shutter was open and, secondarily, the overall exposure level.

This is why I think trying to replicate this under other circumstances is the key. If you can replicate it, I think you may have a sensor problem. If you can't, that suggests something context-specific.

[ST1]

A Google search on:

effects of RF and other high band interference on EOS DSLRs

returns this page as the first hit:

https://www.photo.net/forums/topic/2...on-movie-sets/

Is that what you are looking for?

Thanks for the link, unfortunately the post on that site doesn't include any images, or at least I couldn't see them

Edited to add: The problem image looks like it was taken at Pico do Areeiro, Madeira. I was there in Sept 2022 with my Canon 90D. None of my shots have any banding in them but the 90D is a more recent camera than the 5D mark IV so maybe Canon have fixed the shielding problem alluded to in the photo.net thread??

You're correct regarding the location, given the text in the post on Photo.net it would seem that the issue I had may have been caused by the HF output from the nearby radar/telescopes.
Interesting that you 90D images didn't display any banding, though I don't believe that the 90D has GPS built in, does it?.

Personally I'm leaning towards the issue being created by me having the GPS enabled in my camera.
The affected images are all strangely in portrait mode!, so the camera orientation coupled with the GPS functionality of the camera may have somehow created the issue.

The only way to prove my rather airy fairy theory would be to return to the Island and shoot again.

[stuck]

...I don't believe that the 90D has GPS built in, does it?...

No.

...The only way to prove my rather airy fairy theory would be to return to the Island and shoot again.

That sounds like an excellent plan

[pnodrog]

My concern with some of the hypotheses is that usually Radar and GPS signals are not continuous so unless they were synchronized with the camera I would expect that banding would occur at random places. If you were standing near a microwave or some other communication installation it's possible there is a continuous carrier frequency that caused the problem. It's outside my area of knowledge but I suspect if it is an emi caused problem it's from a continuous source.

[BobGilbody]

I don't think it is useful to bring in extra things to try to resolve the 'mystery' until the more obvious things have been fully addressed.
1. The problem is associated with relatively long shutter times. It seems to me that the issues associated with type of shutter can be ignored.
2. From limited understanding of how a sensor functions I assume that the functioning is the same for all shutter speeds. That is the sensor does not 'pass on' its information, clear itself then start again during the exposure.
3. If 2. is correct the loaded pixel of whatever filtered quality has to hold the 'charge' for the full duration of the exposure.
4. I assume the orientation of the camera was in landscape as opposed to portrait.
5. I assume that readout from the sensor takes place at the end of the exposure.

The colour band is blue [ or cyan ]. It is vertical. It 'disappears' in the well illuminated area of the image.

Peter is the one that has the camera that produced the image. Perhaps if he could repeat a similar image [ high dynamic range ] at shutter speeds of 5 sec, 10 sec, 30sec, and sixty seconds, and manages to capture the 'blue band' we might close in on the problem.

I suggest this is the way to go before we head off to the MoD demanding info on experimental yobba rays.

Just my take on things.

All the best Bob

Sorry senility again. It seems that the image was captured in portrait mode. That suggests to me that it is sensor problem. If the effect were to originate in the yobba ray realm then the question arises 'Why isn't the full frame affected?'.

[stuck]

...If you were standing near a microwave or some other communication installation...

In case it helps, the location looks like this:

[DanK]

It seems to me that the first step is to see whether the issue is the camera or the location. Until Peter has had a chance to try to replicate this in another setting, we're all just guessing.

[William W]

Is that what you are looking for?

Hi,

Thank you, however, it was not that thread.

I am reasonably sure it was later than that date and also longer conversation and that it included an image displaying colour banding in the sky area of the image - it is this last bit that I do remember.

I have searched using many key words, both external (i.e google) and internally on the site using other methods but have had no joy, I suspect it might have been deleted. This old thread had no resolution to "the problem" and was mainly conjecture, but it did have some interesting points on "external interference".

***

Yes I agree with Dan that we are guessing and a first step would be to rule out camera or location.

I'll also add, replicating the fault may be difficult: further I add - NOT being able to replicate it at the same location, does not rule out the location as a cause: I think we all might be guessing for a long time.

It is interesting.

WW

[ST1]

In case it helps, the location looks like this:

For clarity he radome in the image is part (one of four installations)of the Portuguese Military Radar network.


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[ST1]

It seems to me that the first step is to see whether the issue is the camera or the location. Until Peter has had a chance to try to replicate this in another setting, we're all just guessing.

Hopefully over the weekend I'll get time to carry out Dan's suggestions to try and replicate the issue/eliminate the camera from the issue.


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