Strange noise pattern when shooting with LENR

[Aktenschrank]

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Hi everyone,

I recently noticed a strange noise pattern appearing in one of my long exposures shot with LENR switched on and did some investigation afterwards (basically taking it to the extreme to find the cause). The pictures below are both 6min exposures in nearly total darkness. The first one is shot without LENR (and thus shows a lot of hot pixels), the second one in the next post is also a 6min exposure (exact same settings) shot with LENR on. Both shots have been brightened quite a bit to exaggerate the effect. Any idea why LENR seems to treat the left/right parts of the image differently and is actually more noisy than the image without LENR? Have you also experienced something like this?

Disclaimer: These pictures are test pictures taken while investigating. Obviously this effect is way less obvious in any real world scenario😀 I´m just testing out the boundaries of the new camera in order to get to know it´s capabilities and limitations.

Edited January 7, 2020 by Aktenschrank

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shot without LENR

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shot with LENR

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Edited January 7, 2020 by Aktenschrank

[thighslapper]

You need to read the noise primer ..... 

http://www.photonstophotos.net/Emil Martinec/noise.html#thermalnoise

Similar effects were noted on the M9 ..... basically due to data being read from each half of the sensor separately to speed up the process. If you search the various forms of noise and their causes you will find a solution ....

Edited January 7, 2020 by thighslapper

[jaapv]

At this level of amplification, the signal amplifiers on the motherboard cannot be 100% in sync, making this centerfold inevitable. I have the impression that the power supply fluctuated halfway the readout of the sensor right half as well.

Another aspect: RFI (radio interference) can easily cause pattern noise in these extreme conditions ( and even in "normal" high-ISO shots). Even if it may be  going a bit far to encase your camera in a cage of Faraday, it is wise to keep strong sources well away - like your cell-phone or wifi.

[Aktenschrank]

Thanks for your answers @thighslapper & @jaapv . I was reading through the noise primer and doing some more tests, however, I´m not able to find out why this only happens when LENR is set to on. There's not even a glimpse of this sensor "division" when LENR is off, even if the exposure without LENR matches the total "exposure" time of a shot with LENR (12min LENR off, 6+6min LENR on). Anyway, I´ve done more real world test now and I´m pretty confident that I´m never going to see this issue in actual photographs On a side note, those tests also confirmed to me why LENR is there and that I´m definitely going to be using it all the time for longer exposures. Otherwise I would spent hours cleaning up the image afterwards 😀

[jaapv]

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Consider the LENR technolgy. At long exposures there wiil be hot pixels The camera takes a black exposure of the same length and applies it inverted, which eliminates the hot pixels. But it does not eliminate the random noise, in fact it adds it. So the random noise is increased.