M240 long exposures

[01af]

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Leica should [...]

1) be more aware of what the client wants

2) be receptive to comments, suggestions & also criticisms.

Oh, they are! That's how we lost Auto-ISO

[tundraline]

The M still does a dark-frame subtraction since it is still the best way to deal with the inevitable hot pixels; replacing a CCD by a CMOS sensor doesn’t change that.

 

Are you sure that this is indeed the case with the M240 (i.e., that dark-frame subtraction is carried out)? I have read a number of reports of hot pixels in M240 cameras having to be dealt with by sending cameras back to Solms, where the hot pixels are "removed" using software techniques and programming unique to that camera. These reports would seem to indicate that the M240 camera does not possess the built-in ability to deal with hot pixels as they occur, such as by using dark-frame subtraction techniques. Thanks in advance for any illumination you can provide on this topic.

[Guest Gilgamesh]

I still have auto ISO. Don't you?

 

If Leica have removed it in the new firmware (?) you are thus extrapolating that gesture out as listening to customer feedback (?) or you simply making an assumption, making a supposition based upon…… what exactly?

 

I see no way of turning off the NR / dark slide, which is equal in length, time-wise, to the original exposure when shooting below 1 second.

[jaapv]

Are you sure that this is indeed the case with the M240 (i.e., that dark-frame subtraction is carried out)? I have read a number of reports of hot pixels in M240 cameras having to be dealt with by sending cameras back to Solms, where the hot pixels are "removed" using software techniques and programming unique to that camera. These reports would seem to indicate that the M240 camera does not possess the built-in ability to deal with hot pixels as they occur, such as by using dark-frame subtraction techniques. Thanks in advance for any illumination you can provide on this topic.

Two quite different things. A permanent/hot pixel will also be visible at shorter shutter times. The pixel noise that is removed by the black frame subtraction Leica implements is generated by the heat in the sensor caused by the exposure, so the camera will take a second (black) frame of the same exposure length to recreate the noise it has to remove.

[jip]

So if we would take long exposures while it's -25°C I would have less 'hot pixels' than when I would use the camera at +30°C?

[tundraline]

Two quite different things. A permanent/hot pixel will also be visible at shorter shutter times. The pixel noise that is removed by the black frame subtraction Leica implements is generated by the heat in the sensor caused by the exposure, so the camera will take a second (black) frame of the same exposure length to recreate the noise it has to remove.

 

Interesting, and thanks for the information. I know that some non-Leica cameras have algorithms built into their on-board sensors that detect hot pixels and prevent them from providing output signals to the resulting overall image.

[tundraline]

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Sorry, I meant algorithms built into on-board processors (not sensors).

[John Black]

So if we would take long exposures while it's -25°C I would have less 'hot pixels' than when I would use the camera at +30°C?

 

Yes - because ambient temps cool the sensor. Of course -25º C might lead to power issues. Win one, lose one...

[mirekti]

Actually, the M has only 60 not 100 secons. The quesion, if there is a severe hardware reason, or a firmware update could extend the range.

 

Thomas

 

But if you set to self timer, than it is no longer 60 seconds as in the B mode, right?

What is the time limit in that scenario, and what it the maximum duration of black noise reduction frame for M240?

[jaques]

is there any reason why the 'dark frame subtraction' (DFS) process must occur immediately after the shot is taken?

 

It would be great if you had the option to turn on manual DFS as an option- then you could go ahead and apply DFS to individual shots(or apply to all long exposures) in camera in -playback mode- as you like- and if you want. I shot a series of long exposures over a night on a cold riverbank with the m9 - up to 180 seconds each- and the added DFS time really slowed the whole process and limited the number of shots we could do significantly.

 

If I could have applied the DFS after the shoot that would have been great.

 

I also hope Leica consider increasing the long exposure times- I definitely miss them. If their decision is based in image quality considerations- and not technical limitations of the hardware- then I would like to have the option even with IQ degredation.

[jaques]

But if you set to self timer, than it is no longer 60 seconds as in the B mode, right?

What is the time limit in that scenario, and what it the maximum duration of black noise reduction frame for M240?

 

from what I understand 60 seconds is the limit- no matter the settings used. and you can only get 60 seconds at low ISO