M9 constantly underexposes

[SJP]

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see dxo measurents (click iso sensitivity tab)

 

M8 is spot on and M9 underexposes about 1/3 stop

 

comparison graph Compare cameras

 

Edit: I must admit that I do not find this a major problem (er even at all): 1) absolute intensity mesurement is not easy, and you see variation between all cameras, also depending on the metering method (spot, centre weighted etc.), 2) initially I had my M8 set at 0EV and was blowing the highlights all the time, then I set it to -2/3 EV and all was well for some time, but now I am back to 0EV as I am measuring more towards the highlights instead of "the average". So exposure measuring technique is a larger factor than any built in bias.

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[mby]

(...) Would someone check baseline exposure bias for M8? Or point me to a Mac-compatible EXIF reader? (...)

 

Dear Howard,

 

I'd recommend ExifTool by Phil Harvey, it's also available for Mac...

 

Best regards,

Michael

[diogenis]

But presumably you have been happy with the output so if it works.........

 

Andrew

 

Yea I am happy, but 1) I don't use EV compensation -it is 0 and 2) I don't own a M9 -yet

[jaapv]

I suspect that every camera maker will put a value in this field, as it obviously has to do with the sensor character. Can anybody check some other brands? To interpret it as a simple built in underexposure is simplistic to the point of incorrectness.

[diogenis]

see dxo measurents (click iso sensitivity tab)

 

M8 is spot on and M9 underexposes about 1/3 stop

 

comparison graph Compare cameras

 

Edit: I must admit that I do not find this a major problem (er even at all): 1) absolute intensity mesurement is not easy, and you see variation between all cameras, also depending on the metering method (spot, centre weighted etc.), 2) initially I had my M8 set at 0EV and was blowing the highlights all the time, then I set it to -2/3 EV and all was well for some time, but now I am back to 0EV as I am measuring more towards the highlights instead of "the average". So exposure measuring technique is a larger factor than any built in bias.

 

DxO compares ISO and sensor sensitivity as given by manufacturer(specs) and as found by their test equipment (true with whatever method they use to find ISO), not how well the meter performs, or am I mistaken?

[SJP]

I checked my M8 exif data using "photoME" (for PC) but the baseline exposure bias is not listed at all - does this depend on the type of exif reading software?

 

I will check if there is a more recent version of the software to see what that brings. EDIT: I am using the latest version

[SJP]

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DxO compares ISO and sensor sensitivity as given by manufacturer(specs) and as found by their test equipment (true with whatever method they use to find ISO), not how well the meter performs, or am I mistaken?

Mmmm, interesting point. If the camera ISO is set at 1280 but it actually is only ISO 1097 sensitivity (as the graph is suggesting) then images will be underexposed. What I assume they do is set the camera to the ISO value to be measured and compare a standard exposure taken at that setting to what it should have been. But indeed this is assuming that the meter is actually exactly calibrated to the ISO value that the camera claims to be set to. If that is not true then you will get and additional bias on top of the native sensor sensitivity.

[57andrew]

Leica is making sure that, more often than not, the average user obtains usable pictures.

 

Nicolas

 

If that were the case I think the average user would feel a bit insulted as it implies an inability to expose correctly.

[mjh]

I checked my M8 exif data using "photoME" (for PC) but the baseline exposure bias is not listed at all - does this depend on the type of exif reading software?

BaselineExposure isn’t part of the EXIF standard; it is specific to DNG files.

[SJP]

BaselineExposure isn’t part of the EXIF standard; it is specific to DNG files.

I read a DNG file obviously, I also checked if the software was suppressing anything but as far as I can see it is not.

[adli]

Dear Howard,

 

I'd recommend ExifTool by Phil Harvey, it's also available for Mac...

 

Best regards,

Michael

 

Nice tool. Do you know if it possible to change exif data on batches of files?

 

I would like to change the date on my scanned files back to the date when the picture was taken.

[mby]

Did you also see strange local effects in the green channel?

Bayer Green Split               : 500

 

All kidding aside, all those fields describe sensor/camera characteristics and are defined in the DNG specs (http://www.adobe.com/products/dng/pdfs/dng_spec.pdf), which is a highly recommended reading.

 

The DNG-compatible (post-)processor is supposed to take all those fields automatically into account to create a correct picture. - To me, it does not make any sense to peek into the middle of the format definition as long as the post processor is capable of supporting DNG; of course, if the processor does ignore some fields, the resulting picture will - for example - be under-exposed...

 

Best,

Michael

[mby]

Nice tool. Do you know if it possible to change exif data on batches of files?

 

I would like to change the date on my scanned files back to the date when the picture was taken.

 

Sure, there is an extensive documentation on Phil's website (like http://www.sno.phy.queensu.ca/~phil/exiftool/#shift); in an other thread, we used it to copy the Leica-spoecific fields for Aperture and Lens into fields that Apple's Aperture can read.

 

Best,

Michael

[mby]

I'm not sure my opening post was clear enough. Shooting a wide variety of fairly normal subjects my M9 consistently produces under exposed images when exposure is determined by the camera's built-in meter (A mode). It never produces over-exposed images but at least 90% of all images produced are too dark.

 

Here's a snap I took a few days ago with no PP at all.

 

 

Same pic with just +1 stop of exposure applied in Lightroom.

 

 

Maximus, I wonder why your pictures' tags show

ExposureCompensation: -0.332

 

My M9 sets this _always_ to 0 if I've put it to 0 via the menu/dial.

 

Could you post the RAW file?

 

Best regards,

Michael

[diogenis]

Mmmm, interesting point. If the camera ISO is set at 1280 but it actually is only ISO 1097 sensitivity (as the graph is suggesting) then images will be underexposed. What I assume they do is set the camera to the ISO value to be measured and compare a standard exposure taken at that setting to what it should have been. But indeed this is assuming that the meter is actually exactly calibrated to the ISO value that the camera claims to be set to. If that is not true then you will get and additional bias on top of the native sensor sensitivity.

 

ISO is another pillar that if you ask me, also needs be accurate and according to the standard, because then you have a foundation you can depend on and you can use whatever external exposure meter and still be accurate within reasonable limits. Imagine if ISO 320 is not 320 but say, 250, then when you try to find EV you need to compensate for ISO250 as well. Even more parameters to look out, even bigger complexity, unless 1/2 a stop difference is not that important (and it isn't really with the DR of modern cameras).

Personally, I bypass all these factors, just check histograms and when the scene is demanding and contrasty I expose to the limit of burns.

[mjh]

I read a DNG file obviously

Sure, but since BaselineExposure isn’t part of the EXIF standard, there is no guarantee an EXIF reader would display it. There is a wealth of metadata in image files, some defined in the TIFF standard, some in the EXIF standard, and still some more as part of the various raw file standards (or JPEG/JFIF, for that matter). As the basic structure of all these metadata fields is the same, an EXIF reader may decode many more fields than those defined in the EXIF standard proper, but then again, it may not. (If you want to look more closely – maybe your EXIF reader is displaying, but not decoding the data –, the tag value for BaselineExposure is 50730 and the value is of type SRATIONAL.)

[SJP]

Sure, but since BaselineExposure isn’t part of the EXIF standard, there is no guarantee an EXIF reader would display it. There is a wealth of metadata in image files, some defined in the TIFF standard, some in the EXIF standard, and still some more as part of the various raw file standards (or JPEG/JFIF, for that matter). As the basic structure of all these metadata fields is the same, an EXIF reader may decode many more fields than those defined in the EXIF standard proper, but then again, it may not. (If you want to look more closely – maybe your EXIF reader is displaying, but not decoding the data –, the tag value for BaselineExposure is 50730 and the value is of type SRATIONAL.)

Thanks I converted this to hex C62A & looked there but indeed it seems to be missing from photoME (all hide options are off)

 

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[mjh]

Thanks I converted this to hex C62A & looked there but indeed it seems to be missing from photoME (all hide options are off)

It certainly looks like PhotoME doesn’t show all the meta data. BaselineExposure must be there; its value is –1.5 for shots taken at ISO 80 and –0.5 for all other ISO settings.

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Hallo,

Look here: Leica M

[adli]

Sure, there is an extensive documentation on Phil's website (like ExifTool by Phil Harvey); in an other thread, we used it to copy the Leica-spoecific fields for Aperture and Lens into fields that Apple's Aperture can read.

 

Best,

Michael

 

Thanks, this was very useful!

 

Arne Adli

[Jamie Roberts]

Maximus, I wonder why your pictures' tags show

ExposureCompensation: -0.332

 

My M9 sets this _always_ to 0 if I've put it to 0 via the menu/dial.

 

Could you post the RAW file?

 

Best regards,

Michael

 

I noticed this awhile back, too That could certainly explain almost a stop underexposure on an average scene if Leica is also "setting" a -.5 adjustment as a baseline.