SL2: Excessive noise on long exposure?

[PhotoCruiser]

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So I went a few days ago to shoot some long exposure sunset photos and when I checked them at home on the computer I found this strange noise as on the screenshots below.

Noise get worst as higher f/stop is what should point towards a dirty lens, but honestly I don't find lens or sensor dirty.
As exposure time rises up to 60 seconds at f/16 I start to believe that it's the sensor itself, maybe overheating?
I got one year warranty by Leica shop in Zurich and I would to settle this before warranty becomes due in January.

Any suggestions if this is normal or if I should discuss this with Leica?
 

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Edited 11 hours ago by PhotoCruiser

[PhotoCruiser]

About 10 minutes earlier same f/16 did not show such much colour spot noise either at ISO1 00 or ISO 6400

 

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[PhotoCruiser]

This is the whole photo where obviously the spots are not visible.
The one screenshots is lower left corner, but spots are all over the affected  photo.

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[EUSe]

I think these are hot pixels. You cannot totally avoid them, the worst can be mapped out.

[jaapv]

Hot pixels can be corrected on sensor level by switching on LENR ( not sure if this is available on the SL2) 

But why should you use f16? You are well into diffraction IQ degradation. 

[LocalHero1953]

I'm looking at this on my greasy and speckled laptop screen so can't easily see what you mean. But are you running your exposures with LENR? 

Edit. I see Jaap has mentioned the same issue. The SL2-S certainly had LENR - it was more a matter if it could be switched off (I can't remember).

Edited 10 hours ago by LocalHero1953

[PhotoCruiser]

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vor einer Stunde schrieb jaapv:

But why should you use f16? You are well into diffraction IQ degradation. 

I did some quick tests with long exposure as sky was nice for that so i went to the beach nearby.
As i still don't have a ND filter so i needed to use f/16 to get very slow shutter speed to make the sea looking as a blanket.
Chris

 

Edited 9 hours ago by PhotoCruiser

[PhotoCruiser]

vor einer Stunde schrieb LocalHero1953:

I'm looking at this on my greasy and speckled laptop screen so can't easily see what you mean. 
But are you running your exposures with LENR? 

Huhh, then you have a very dirty screen, have you checked the last photo of my first message and maybe clicked on the photos to see them bigger?
I think i switched LENR off for the test environment/purpose, but not 100% sure.
 

vor 1 Stunde schrieb EUSe:

I think these are hot pixels. You cannot totally avoid them, the worst can be mapped out.

That would be a very high number of hot pixels and as shown on the various photos, they disappear at wide open.
Would hot pixels not appear always, independently of f/stop?

 

Thanks for the replies, I see, i need to repeat the photos with LENR activated and off not to see if this helps and/or makes any difference.
Chris

Edited 9 hours ago by PhotoCruiser

[jaapv]

No, because it depends on the temperature of the sensor. 

[PhotoCruiser]

vor 9 Minuten schrieb jaapv:

No, because it depends on the temperature of the sensor. 

The hot pixels i guess?
So hotter sensor = more hot pixels?

One doubt i have is that it was the heat leading to this excessive amount of coloured spots, but that would be a serious issue for night and astro photography. I probably should conduct a test with even longer shutter times to see if problem get worse.
I took 12 minutes before 3 thirty second long videos but camera was off between series i shot every approx 5 minutes.
The affected photo is the last i took, but took others with same 60 sec shutter time and much less coloured spots.
Below a detail how they look
Chris

 

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Edited 7 hours ago by PhotoCruiser

[LD_50]

I’m confused by the exposure choices. 60 seconds at f/16 and ISO 6400?

This looks to me like the type of long exposure noise I’d expect without LENR on. I don’t know why you’d choose those settings though. You mentioned f/16 to run a longer exposure, so why then run ISO 6400?

[PhotoCruiser]

As i wrote, i conducted some tests with different camera settings.
The ISO 6400 was to test how much noise the high ISO will produce and if 6400 can be used for darker situations.
I like to conduct (extreme) tests on my cameras to know how to get the best out of them and their settings.
Chris

[LD_50]

I understand testing. I don’t understand testing setups for which I can see no application. 

[jaapv]

Still this is a fact.  Sensors heat up during longer activation, adding pseudo-photons so some pixels become over saturated (hot); and you were working cumulatively. In astrophotography sensors have active cooling precisely because of this. 
https://www.skyatnightmagazine.com/advice/why-do-i-need-to-cool-my-camera

This can start at exposures over one second and increases for longer exposures. 
Thus Leica even had mandatory LENR  until forced to make it optional for users who were not familiar with with this. Heat noise cannot be eliminated satisfactorily by any other method. 

[PhotoCruiser]

If i would have waited for another 30 minutes or a hour in the cold i could have shoot with F1.8 and 6400, but i preferred to go home so i cranked up ISO and aperture.
However, my question was not about ISO 6400 or my test methods, the noise is in the photo with ISO 400 and same in a lower quantity in a photo with ISO 100.
Chris

[PhotoCruiser]

vor 3 Minuten schrieb jaapv:

Still this is a fact.  Sensors heat up during longer activation, adding pseudo-photons so some pixels become over saturated (hot); and you were working cumulatively. In astrophotography sensors have active cooling precisely because of this. 
https://www.skyatnightmagazine.com/advice/why-do-i-need-to-cool-my-camera

Thanks Jaapv.
Then it's probably that what i guessed, the sensor getting hot.
I know the problem of overheating sensor from underwater video where many had mostly problems with camera switching off that during longer recordings using digital cameras instead of video cameras. What i am surprised that this happens on my SL2 after such short time of use.
If weather gets better before i leave i will redo the tests but next time concentrating on

• if and how much LENR set to on will mask the hot pixels and if there is a recording quality loss
• verify if longer shutter times and/or video clips to see if i can repeat the visible number of this noise
• use my 28mm 1.4 DG HSM to see if there is a difference between both lenses
• dress up better to avoid getting cold and be able to use normal apertures for night photos

Chris

 

[LocalHero1953]

LENR kicks in after a few seconds: 3-7 depending on ISO in the SL3-S, according to the manual.
You may want to check the manual for the SL2, but from recollection it was similar.

TL:DR
This is normal behaviour, not a fault.

[PhotoCruiser]

vor 20 Minuten schrieb LocalHero1953:

You may want to check the manual for the SL2, but from recollection it was similar.

Thanks!
The SL2 Manual does not state after how much seconds LENR kicks in, just that time remainig will be shown on the display.
Reading the manual i realized that i mixed jpg noise reduction with LENR, my fault and thats the reason i conduct some tests as i learn better doing them as reading a manual what i always do.
Next test i will switch it on as it would have probably eliminated the coloured pixels as this is what it's made for.
Chris

 

Edited 5 hours ago by PhotoCruiser

[LD_50]

54 minutes ago, PhotoCruiser said:

Thanks Jaapv.
Then it's probably that what i guessed, the sensor getting hot.
I know the problem of overheating sensor from underwater video where many had mostly problems with camera switching off that during longer recordings using digital cameras instead of video cameras. What i am surprised that this happens on my SL2 after such short time of use.
If weather gets better before i leave i will redo the tests but next time concentrating on

• if and how much LENR set to on will mask the hot pixels and if there is a recording quality loss
• verify if longer shutter times and/or video clips to see if i can repeat the visible number of this noise
• use my 28mm 1.4 DG HSM to see if there is a difference between both lenses
• dress up better to avoid getting cold and be able to use normal apertures for night photos

Chris

 

I get what you’re saying about limited time and it being cold during testing, but I think I’m still missing something on the need for high ISO in combination with f/16. I’m not trying to argue with you, just sharing that there are options to get what you said you wanted (long shutter speed) without having both the high ISO and the small aperture. 

Example of roughly equivalent exposures:

- f/16 + 60” + ISO 6400

- f/2 + 60” + ISO 100 

- f/8 + 60” + ISO 1600

- etc

So to get the look you’re after, you could shoot a much lower noise photo without the high ISO setting.

Edited 5 hours ago by LD_50

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[jaapv]

The first two tests are superfluous. LENR works by taking a second equal exposure, determining which pixels are affected and mapping them out. It cannot be compared to other systems of noise reduction as those work by a blurring algorithm and/or AI driven pattern recognition. BTW the colour of the pixels does not come into it; a sensor does not record colour. That comes later in the process, after LENR. The only thing a sensor pixel does is count photons.