Help please! Horizontal 'noise' as lines

[BFMount]

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I took a very underexposed shot and tried raising the exposure 3.4 stops, and I expect noise, but what are these horizontal lines? Is it normal? This was taken with my 'new' used LeicaQ. Is this expected? I've never seen this before, and I've definitely shot underexposed before. Should I return this camera? Is it defective? Thank you!

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[jaapv]

LED lights, I suppose...

[happymac]

This is normal if you have severely underexposed the picture.

[BFMount]

There is an LED lamp behind me in the corner, and the TV I suppose. Thanks!

[Leica Guy]

I’d say it’s normal. The Q is known for having some banding when raising shadows in a very underexposed image. Normally this is not a problem or at least not a significant one. Expose to the right. Shoot RAW. You’ll love the images from the Q. 

[jaapv]

Given the relatively low level of noise for the situation here, I do think that the banding we are seeing is (local) light contamination by a LED source, not noise banding.

[antigallican]

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There's no magic in digital cameras, despite what manufacturers claim. My understanding is that if you are trying to raise the sensitivity by 3 or 4 stops you are trying to extrapolate information from the exposure by index 3 or 4. If we give the exposure a nominal value of 2, that means you are trying to extract 2x2=4, 4x4=16, 16x16=256 times the information from your base exposure. Of course this doesn't work with a value of 1 and no doubt one of the engineers or mathematicians who post here will quickly correct me if I'm wrong. In any case, it's a hell of a task you're setting for a file which has a fixed value.

Edited August 25, 2020 by antigallican
clarification

[Siriusone59]

Should be fairly easy to recreate and test both with and without the TV and LED light and with exposure increased to normal.  I think both the 3-4 stops under and the blown out TV light source are the main problem.  Your camera and software is just doing all it can to correct it.

[BFMount]

7 hours ago, antigallican said:

There's no magic in digital cameras, despite what manufacturers claim. My understanding is that if you are trying to raise the sensitivity by 3 or 4 stops you are trying to extrapolate information from the exposure by index 3 or 4. If we give the exposure a nominal value of 2, that means you are trying to extract 2x2=4, 4x4=16, 16x16=256 times the information from your base exposure. Of course this doesn't work with a value of 1 and no doubt one of the engineers or mathematicians who post here will quickly correct me if I'm wrong. In any case, it's a hell of a task you're setting for a file which has a fixed value.

Yeah, the underexposure was not intentional, believe me. I had mounted a used SF24d for the first time and was trying to figure it out without reading the manual. It's just that I've never seen this banding before in all my years of lightroom, since the original canon digital rebel. Noise, sure, and it's expected, but not banding. I believe the other responders are correct, had something to do with lighting from the TV and my lamp in the corner, it's an led bulb. Thanks for responding!

[Miltz]

your camera is NOT defective and 100% normal. What you are seeing is the property of the sensor when underexposed to that degree in the shadows. 

[jaapv]

Make no mistake - extreme underexposure will result in banding or even tartan patterned noise. Leica cameras use relatively light noise reduction, leaving much of the choice between loss of detail and colour versus noise to the photographer in postprocessing, so may well produces more noise at first sight. Other brands can be somewhat more heavy-handed, which can give a false impression of "no noise" .

BTW, a cell-phone next to the camera can, in some cases, lead to banding as well.

[jaapv]

1 minute ago, Miltz said:

your camera is NOT defective and 100% normal. What you are seeing is the property of the sensor when underexposed to that degree in the shadows. 

Not of the sensor - a property of the in-camera processing pipeline creating a pattern out of random  noise. - If this is noise banding, which I doubt.

[Miltz]

3 hours ago, jaapv said:

Not of the sensor - a property of the in-camera processing pipeline creating a pattern out of random  noise. - If this is noise banding, which I doubt.

Well the pattern is not random. The exact same pattern appears when an image is underexposed and then boosted. The darker the shadows the most you see it. 

[Jared]

Pretty sure it’s not an artifact of LED lighting or the TV screen. The stripes are too narrow for thata d are much worse in deep shadows. It’s just from the under exposure.  Totally normal (if occasionally annoying).