Shutter Speed Limitations at Higher ISO

[teids]

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Hi

 

While shooting in Bulb mode I realised that at higher ISO s the M limits you for shooting at certain shutter speeds:

 

For Example

 

ISO 200- 60 Sec

ISO 250 up to ISO 400 - 32 Sec

ISO 500 up to ISO 800 - 16 Sec

ISO 1000 up to ISO 3200 - 8 Sec

 

I am currently running firmware 2.0.3.0

 

Based on Leica website I found this information:

"These limits have been set to prevent uncorrectable imaging errors caused by longer exposure times."

 

I find this a bit furstrating but I guess nothing can be done...?

 

It seems that this does not apply on the SL nor on the Q, does it apply as well on the M 10

 

Thank you

[adan]

M10 is similar, but with a bit more range

ISO 3200 = 16 seconds

ISO 1600 = 32 seconds

 

SL goes to 30 Minutes at any ISO, C has a fixed 30-sec. limit at any ISO (I believe).

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[jdlaing]

Heat

[adan]

The deal - of course - (as jdlaing says, even as I write) is that long time-exposures produce two kinds of image noise on top of the basic ISO noise. Fixed noise (stuck pixels) that can be detected by the following "dark" exposure and removed by in-camera noise removal processing - and also thermal noise (the sensor heats up if it is "on" for a long time) which is photons of infrared light produced by the warm chip itself, which show up as additional noise that is totally random from exposure to exposure, and thus cannot be detected and removed by a second "dark" exposure.

 

ISOs are, of course, simply "amplification" or "pushing" of the sensor output. The noise that would occur with a 32-second exposure is "acceptable" (in Leica's opinion) when the ISO is set to only 1600, but would be "unacceptable" if increased by the extra stop's-worth of amplification to get to 3200, thus 3200 is limited to 16 seconds (and low-ISO-200 exposures with less amplification can run to 60 seconds).

 

The SL's larger body probably incorporates a larger heat sink to conduct away sensor heat in long exposures and reduce the thremal radiation, thus it can get to 30 minute exposures. In the smaller M bodies, there is less room for ventilation and "wicking away" the heat build-up (unless one sacrifices something else, like the size/capacity of the battery).

Edited May 7, 2018 by adan

[Echo63]

A handy tip to know - if you set the shutter speed dial to "B" (bulb mode) then press and hold the front focus assist button, a menu will pop up on the rear LCD that will allow you to select a shutter speed to use.

If you are using higher ISOs the unavailable options are greyed out.

makes it a bit easier to do long exposures - set the self timer to two seconds (to give the camera a chance to stabilise after pressing the shutter) and preset the right exposure - no need to dig the cable release out of your bag.

[jmahto]

A handy tip to know - if you set the shutter speed dial to "B" (bulb mode) then press and hold the front focus assist button, a menu will pop up on the rear LCD that will allow you to select a shutter speed to use.

If you are using higher ISOs the unavailable options are greyed out.

makes it a bit easier to do long exposures - set the self timer to two seconds (to give the camera a chance to stabilise after pressing the shutter) and preset the right exposure - no need to dig the cable release out of your bag.

I didn't know this. Thanks.

[Echo63]

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I didn't know this. Thanks.

I actually found it by accident, while taking the camera off a tripod after a shoot where it would have been really helpful....