Some M Monochrome (Typ 246) Measurements

Started May 16, 2016 | Discussions
bclaff Veteran Member • Posts: 4,850
Some M Monochrome (Typ 246) Measurements
3

I have complete measurements for the M Monochrome (Typ 246).
Some of the results are "interesting".

Since this sensor in monochrome the Quantum Efficiency (QE) is much higher than that for an ordinary sensor with a Color Filter Array (CFA).
Since more electrons are produced for the same amount of light the base ISO is higher than "normal" at ISO 320.

The sensor seems to use dual conversion gain technology.
This kicks in at ISO 800 as is evident by the Read Noise in DNs :

As well as the Photographic Dynamic Range (PDR) :

It looks like ISO 800 is a good place to be and the sensor is pretty much ISO Invariant above that.

Fixed Pattern Noise (FPN) is somewhat unusual:

Left: Dark Signal Non-Uniformity (DSNU) Right: Photo Response  Non-Uniformity (PRNU)

(This visualization has been manipulated to make the patterns stand out more distinctly.)

DSNU is not likely to appear in any real photography since Leica clips raw data very severly at 0.

The PRNU is very subtle unless pushed hard and is also not likely to appear in normal photography.

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Bill ( Your trusted source for independent sensor data at http://www.PhotonsToPhotos.net )

Leica M Monochrom (Typ 246)
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User5114438916 New Member • Posts: 1
Re: Some M Monochrome (Typ 246) Measurements

Hi Bill,

first of all I would like to thank you for your great work for all of us who are interested in sensor analysis and performance.

I happen to have bought the M246 just last week and was a bit unhappy that there was no test out there, especially because monochrome sensor is quite different from the usual color filtered.

I made myself a simple test for ISO invariance (a quality that I appreciate very much in modern sensors); this is something I do empirically by taking different shots, pushing exposures and judging the increase in noise, and my finding is that invariance starts from ISO 1600 rather than 800. All the exposures look the same (ISO 12500, 6400 pushed 1 stop, 3200+2, 1600+3) but the 800+4 looks distinctly worse, also with a lot of white spots appearing.

What do you think? Here is a screenshot:

Many thanks

Michele

OP bclaff Veteran Member • Posts: 4,850
Re: Some M Monochrome (Typ 246) Measurements

User5114438916 wrote:

Hi Bill,

first of all I would like to thank you for your great work for all of us who are interested in sensor analysis and performance.

I happen to have bought the M246 just last week and was a bit unhappy that there was no test out there, especially because monochrome sensor is quite different from the usual color filtered.

I made myself a simple test for ISO invariance (a quality that I appreciate very much in modern sensors); this is something I do empirically by taking different shots, pushing exposures and judging the increase in noise, and my finding is that invariance starts from ISO 1600 rather than 800. All the exposures look the same (ISO 12500, 6400 pushed 1 stop, 3200+2, 1600+3) but the 800+4 looks distinctly worse, also with a lot of white spots appearing.

What do you think? Here is a screenshot:

What you might be seeing is that Fixed Pattern Noise (FPN) becomes less visible as you raise the ISO setting.
It is true that shadow performance rises slightly from ISO 800 to ISO 1280 :

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InTheMist
InTheMist Veteran Member • Posts: 3,078
Re: Some M Monochrome (Typ 246) Measurements

Great analysis, Bill. Most curious.

-Tim H.

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Leica M Monochrom (Typ 246) Leica M-Monochrom Nikon 1 AW1 Nikon Df Nikon D810 +18 more
InTheMist
InTheMist Veteran Member • Posts: 3,078
Re: Some M Monochrome (Typ 246) Measurements

I did some test scenes at ISO 320 and ISO 800 if anyone wants to see them.  Definitely at base ISO, pushing the shadows ends up in smearing, while at 800, it's more salt-and-pepper, which I prefer.

It's going to change how I shoot, I think.

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Leica M Monochrom (Typ 246) Leica M-Monochrom Nikon 1 AW1 Nikon Df Nikon D810 +18 more
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