ISO 100 on M10

[otto.f]

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I have to say that to me, these show ISO 100 is NOT a pull-process ISO. Whatever was giving me grayed-out color in other shots was - something else. The DR is virtually indistinguishable from ISO 200.

 

 

Thanks for making this explicit, I copy it here just to diminish rumors.

I do how ever see a less bright highlight at 200, in #40 and at #38, which is in fact contrary to your earlier statement.

I'd say if you want 'pop', stay with 100

[Overgaard]

For me, Auto-ISO is something that happens to other people.

 

 

Ha ha, best ever.

 

Can we get t-shirts, mugs and caps produced with that slogan :-)

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[01af]

I have to say that to me, these show ISO 100/21° is NOT a pull-process ISO.

Huh!?  

 

 

Whatever was giving me grayed-out color in other shots was—something else.

What makes you think so? The graying-out of highlight colour sure is some sort of artifact. But the fact that it happens near RGB 240 at ISO 100/21° and near RGB 250 at ISO 200/24° means that the useful output range is narrower at ISO 100/21° for a given high-contrast input range. If that doesn't mean 'pull' then what would?

 

 

The DR is virtually indistinguishable from ISO 200/24°.

"Indistinguishable"!? The higher apparent contrast in the ISO 100/21° shot is totally obvious—which means narrower exposure range.

 

 

Case 2 (perhaps unnecessary)—medium contrast (sun behind bright cloud).

Medium-contrast test cases are pointless. It's the high-contrast scenarios where pull-processing will do damage.

 

What remains to be tested is—what is base ISO, actually? We all are assuming if it isn't ISO 100/21° then it must be ISO 200/24°, right? Well, it just as well might be ISO 250/25° ... or ISO 320/26° ... or maybe even ISO 400/27°. After all, maximum ISO goes up all the way to ISO 50,000/48° ...

[Leicauser7]

Can't one of the many people that moderate or participate in this forum that are tight with Leica just pick up the phone and find out the answer from Leica? What's the big deal to Leica in letting everyone know, is it a big secret for them?

 

 

Sent from my iPhone using Tapatalk

Edited March 1, 2017 by Leicauser7

[Hoelzi]

The technical data info from Leica (https://de.leica-camera.com/content/download/139047/2224744/version/1/file/Technical_Data_M10.pdf) reads "ISO 100 to ISO 50000, adjustable in 1/3 ISO increments from ISO 200". So I think 200 is base ISO.

Edited March 2, 2017 by Hoelzi

[Dirk Mandeville]

Interesting observation: Horatio Tan has discovered that the M10 sensor underexposes by one stop. In other words, if a scene is metered with an independent light meter, and those settings are used, the photo will be underexposed by one stop. The M10 meter overexposes by one stop in order to correct for this. In other words, the meter of the M10 will give a reading overexposed by one stop compared to any other meter reading of the same scene.

 

I'm curious how this plays into discussions regarding base ISO.

[otto.f]

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Maybe it's just me but I'm coming from an M9 and I mostly underexpose with this camera, about 2/3. I don't do that anymore with my M10, it's perfect as it comes

[adan]

@ 01af:

 

Regarding the grayed-out colors. In the most recent sample I posted, that did not occur, in a reddish highlight. It did occur in some other places with either: highlights that were very close to neutral white/gray to begin with, or slightly bluish (as in edw's samples previously linked to).

 

I had similar graying of high-brightness blue highlights in some early M9 pictures 7 years ago - even at ISO 320. However, I just revisited those pictures, and given additional processing options not available in 2009 a month after the camera's intro (an Adobe profile as well as the Embedded profile, and updated "processes" from Adobe (2010 and 2012)), I can now make them go away with a click of a button.

 

They were artifacts of the raw processing of the moment, not the sensor or the in-camera processing. Therefore, their source in the M10 is a open question. When Adobe gets around to issuing their own profile for the M10 - or Leica adjusts their firmware, who knows what we'll see?

 

As to the dynamic range: As previously noted, the M10 exposed the ISO 200 shot slightly less (equated to ISO) than it did the ISO 100 shot. By a small amount, but on the order of 7% less light.

 

Result, darker highlights that blow out less.

 

I processed the shadow recovery for the two images and got equal brightness via processing, but more shadow noise at 200. Redoing the shadow recovery for equal noise (equal std. deviations in gray patches) at ISO 200 results in darker shadows with less tonal separation. (see attached). And noise has to be factored into DR. cf: "noise floor"

 

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The ISO 200 picture is simply a slightly darker overall exposure, perfectly consistent with the differing exposure given (1/750 at ISO 200, but 1/350 (not 1/375) at ISO 100).

 

The highlights have more tonal detail, the shadows have less tonal detail (unless pulled up to a noisy level). The net range is about identical.

 

However, I have an open mind. I'm willing to listen to or look at new facts. It is certainly suggestive that ISO 100 "stands alone" in the menu, without options for 125 or 160.

Edited March 2, 2017 by adan

[jonoslack]

 

What remains to be tested is—what is base ISO, actually? We all are assuming if it isn't ISO 100/21° then it must be ISO 200/24°, right? Well, it just as well might be ISO 250/25° ... or ISO 320/26° ... or maybe even ISO 400/27°. After all, maximum ISO goes up all the way to ISO 50,000/48° ...

Or possibly ISO 130, or 150, or 175?

 

I've really enjoyed reading this post, especially your contributions Andy, I'm right with you - you spend a few weeks obsessing about what is, and what isn't, and then you take photos . . It's been a while since I've stopped obsessing.

 

It seems to me

 

1. Don't over-expose (it was always thus)

2. ISO 100 is a useful addition, whether or not it's pull. Personally I never used pull on the M240, but now I'm wondering if there were circumstances when I should have.

3. The amount of shadow detail in the M10 files is wonderful, and the colour doesn't get weird either (back to 1).

 

I can say this because I really don't know the actual base ISO either . .

[Overgaard]

Interesting observation: Horatio Tan has discovered that the M10 sensor underexposes by one stop. In other words, if a scene is metered with an independent light meter, and those settings are used, the photo will be underexposed by one stop. The M10 meter overexposes by one stop in order to correct for this. In other words, the meter of the M10 will give a reading overexposed by one stop compared to any other meter reading of the same scene.

 

I'm curious how this plays into discussions regarding base ISO.

 

 

1) The M240 and the M10 reads the exposure the same at 200 ISO using a Grey Card (18% reflective).

 

2) The M10 reads the exposure no differently than expected at 100 ISO (if 200 ISO exposure was 1/1000, the 100 ISO metering will show 1/500)

 

3) Both he M240 and M10 reads the exposure from a Grey Card 1/2 (to 1/1 stop) brighter than an external light meter.

 

4) Changing metering method in the M10 from Center-weighted to Multi-field or Spot Meter does not change the reading of exposure reding from a Grey Card.

 

5) According to Leica, the M10 base ISO is "Somewhere between 100-150 ISO".  

 

 

In this example, the light meter reads 1/750 and the camera reads 1/500:

 

Here is the same photo corrected to 1/750 which gives the correct exposure of the Grey Card (50% Red, 50% Green, 50% Blue):

 

Edited March 2, 2017 by Overgaard

[digitalfx]

Interesting observation: Horatio Tan has discovered that the M10 sensor underexposes by one stop. In other words, if a scene is metered with an independent light meter, and those settings are used, the photo will be underexposed by one stop. The M10 meter overexposes by one stop in order to correct for this. In other words, the meter of the M10 will give a reading overexposed by one stop compared to any other meter reading of the same scene.

 

I'm curious how this plays into discussions regarding base ISO.

 

 

Huh??

This makes absolutely no sense.

[Dirk Mandeville]

Huh??

This makes absolutely no sense.

I don't understand it either. Basically, he did a comparison, metering the same scene with his M10 and half a dozen other cameras as well as an independent light meter. He found that the M10 meter consistently read the scenes 1 stop overexposed compared to every other meter. He then found that when he shot the scene according to the independent light meter reading, shooting the scene in all half dozen cameras and M10 with the same settings, the M10 consistently rendered the scene a full stop underexposed compared to all the other cameras.

 

What does it mean? That's beyond my technical expertise. It could just be his camera. But Thorsten's comments above seem to confirm the behavior and say it extends to the M240 as well.

[adan]

3) Both [t]he M240 and M10 reads the exposure from a Grey Card 1/2 (to 1/1 stop) brighter than an external light meter.

 

Yep.

 

I won't bore everyone with a shot of an even-toned, evenly-lit gray sidewalk, but the M10 meter overexposed it so that with default ("0") raw exposure settings, it comes out at a level/brightness of 137 (46% gray). Brighter than the nominal median gray (50%=128) on the 8-bit scale (0-255 levels). Thorsten's M10 meter seems to be running a bit brighter yet (around 151, 41%) - just eyedroppering his M10-exposed gray card.

 

That should not have anything to do with dynamic range directly, though, except to introduce experimental error. The meter reading may be imperfect, and the actual technical ISO in use may be unknown (by small amounts)

Edited March 3, 2017 by adan

[Sharpdressed]

I don't understand it either. Basically, he did a comparison, metering the same scene with his M10 and half a dozen other cameras as well as an independent light meter. He found that the M10 meter consistently read the scenes 1 stop overexposed compared to every other meter. He then found that when he shot the scene according to the independent light meter reading, shooting the scene in all half dozen cameras and M10 with the same settings, the M10 consistently rendered the scene a full stop underexposed compared to all the other cameras.

What does it mean? That's beyond my technical expertise. It could just be his camera. But Thorsten's comments above seem to confirm the behavior and say it extends to the M240 as well.

M240 (and probably M10 too as the sensor is a lot similar) iso 200 is in reality ~140, that's why it will slightly underexpose compared to an external meter set to the same value. Edited March 3, 2017 by Sharpdressed

[olgierdc]

I have a difference between M240 and the lightmeters about 1 1/3 EV (Gossen Starlite 2 and Seconic L-478DR).

Edited March 3, 2017 by olgierdc

[gpwhite]

I have a difference between M240 and the lightmeters about 1 1/3 EV (Gossen Starlite 2 and Seconic L-478DR).

 

Yes!  With a Bayer filter on the sensor to give you RGB, you lose 1 stop. So an M10 monochrome, without this filter, will have a native ISO equivalence similar to your hand meters.

 

Additionally, the M has a mild IR cover glass on top of the sensor, so you lose another bit. All things considered, your tests have validated and replicated the EV precision of the Leica M light meter. Congratulations 

[adan]

Yes!  With a Bayer filter on the sensor to give you RGB, you lose 1 stop. So an M10 monochrome, without this filter, will have a native ISO equivalence similar to your hand meters.

 

Additionally, the M has a mild IR cover glass on top of the sensor, so you lose another bit. All things considered, your tests have validated and replicated the EV precision of the Leica M light meter. Congratulations 

 

I'm sorry, gp - but that is just not correct. Leica changes the ISO range and the metering to go with it, when they remove the Bayer filtering.

 

Your statement amounts to saying that ISO 100 color film must be a stop slower than ISO 100 B&W film (because color film also has light-robbing color filters to distinguish colors in the various layers).

 

In either film or digital, the underlying material (silicon or silver) has a basic sensitivity to visible light. The manufacturers do understand that if they add filtering** to distinguish colors (per pixel in Bayer-digital, per layer in film) - then the final sensitivity will be lower. The M Monochrom silicon is ISO 320. The M9 silicon is identical, but the filtering reduces its effective ISO to 160 - just as it says on the box. And when you set the M9 to ISO 160, the meter reduces the shutter speed by a stop, compared to using 320.

 

As to the IR cover glass - its affect on visible light is roughly equal to a UVa filter placed over the lens. Neglible to zero. No "filter factor." Or at least not more than glass alone. Glass absorbs light, which is why motion picture cameramen refer to "T/stops" - transmission stops, or how much light a lens passes, considering not just the aperture, but also the losses to reflections and absorption by the glass itself. I hate to break it to Noctilux f/0.95 users, but a cinematographer would consider that just a lowly T/1.01 lens.

________________

 

**technically speaking, in film the "filtering" may be achieved with sensitizing dyes rather than filters, but the net result is the same - each color layer only responds to about 1/3rd of the incoming light, thus the ISO is reduced.

Edited March 3, 2017 by adan

[gpwhite]

I'm sorry, gp - but that is just not correct. Leica changes the ISO range and the metering to go with it, when they remove the Bayer filtering.

 

Your statement amounts to saying that ISO 100 color film must be a stop slower than ISO 100 B&W film (because color film also has light-robbing color filters to distinguish colors in the various layers).

 

In either film or digital, the underlying material (silicon or silver) has a basic sensitivity to visible light. The manufacturers do understand that if they add filtering** to distinguish colors (per pixel in Bayer-digital, per layer in film) - then the final sensitivity will be lower. The M Monochrom silicon is ISO 320. The M9 silicon is identical, but the filtering reduces its effective ISO to 160 - just as it says on the box. And when you set the M9 to ISO 160, the meter reduces the shutter speed by a stop, compared to using 320.

 

As to the IR cover glass - its affect on visible light is roughly equal to a UVa filter placed over the lens. Neglible to zero. No "filter factor." Or at least not more than glass alone. Glass absorbs light, which is why motion picture cameramen refer to "T/stops" - transmission stops, or how much light a lens passes, considering not just the aperture, but also the losses to reflections and absorption by the glass itself. I hate to break it to Noctilux f/0.95 users, but a cinematographer would consider that just a lowly T/1.01 lens.

________________

 

**technically speaking, in film the "filtering" may be achieved with sensitizing dyes rather than filters, but the net result is the same - each color layer only responds to about 1/3rd of the incoming light, thus the ISO is reduced.

 

I understood the post to say that when he took a reading with the M, he got, for example, ISO 100 125th @ f/2, but when he carefully checked with his hand meters, he got 250th and some change for reflection off the same spot.

 

Did I not understand his circumstances correctly? 

 

In other words, his light meters gave the actual EV. But, his M meter said it needed another stop plus for the sensor to accommodate its Bayer filer, etc., at that EV.

 

My comparative comments had to do with the filtration on the M and lack of it on the Monochrome. Nothing at all to do with film emulsions. But maybe you know...  in designing a color reversal emulsion, are they typically less sensitive to daylight spectrum than say Scala? In other words, in achieving comparable DR and grain, are color reversal emulsions likely to rate at a lesser ISO than something like Scala? 

 

Regarding the IR filter, there is so much variability in highly technical comparisons on line. I do read your posts and have alwasys assumed you have deep technical skill, but I would also relate my experience with the M8 IR cut filters, btw, which did not always have zero effect. Of course we could examine this point more closely by having the OP above take the IR filter out of his M,  , and test it in front of his light meters.

 

Whatchyathink?

[olgierdc]

I just don't understand why they push exposition ca. +1 EV. It is so easy to burn highlight.

Comparing with light meter having ISO 200 in M, I have to set ISO 80 or 100 in light meter to have the same time in given aperture.

It means that real ISO is 100 and the real lowest ISO is 50 (setting 100 in M camera). 50 ISO must be PULL.

 

Am I wrong?

Edited March 3, 2017 by olgierdc

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[adan]

@gpwhite

 

You are just fine on the circumstances.

 

It's quite possible, and even normal, that any two meters will give different readings and suggest different exposures.

 

I would not assume that an external meter gave "the actual EV" - just "a different EV."

 

But that has nothing to do with the Bayer pattern. It's just that Leica's idea of a "good" exposure, and Sekonic's idea of a "good" exposure, and an expert photographer's idea of a "good" exposure, can all be different.

 

The Bayer pattern losses are taken into account in specifying the ISOs available. An M240 can be set to ISO 200; an M246 can't be set to lower than 320 - that right there takes care of the Bayer color filter effects. Set to any ISO that they have in common (say, 400) - the Leica built-in meters will give the same exposure with either camera. And the two images will be equally bright, but the M240 will have more noise (that's where the Bayer filtering losses will show up). And quite probably, if you metered with the M246 @ ISO 400, and then set the M240 to the same shutter speed and aperture (just using the Monochrom as your "meter"), that the picture brightness would be the correct (but the 240 would still show more noise). And a third-party meter may still recommend something different that the Leica camera meters.

 

As to a color slide film vs. Scala:

 

First, you must understand that film makers are allowed some "artistic license" to create a film they believe is more attractive, or tuned for portraits, or tuned for landscapes, or tuned for clothing colors (fashion). There was Kodak E100VS, with more contrast and saturation and grain, and less DR, and there was plain E100. There was E100N, which was specifically tweaked to handle a certain kind of blue analine clothing dye, that was rendered too purple on regular films (Kodachrome 25/64, or the original 1980's E100). Fuji makes their own creative choices - which is why Velvia or Astia or Provia don't look like any Kodak film. One can presume that Agfa made similar "creative decisions" in engineering Scala - "This is how we want Scala to look."

 

And some people like Velvia 50 exposed at 50 ISO, and some at 40, and some at 32. (And some don't like it at all )

 

Which of those did you want me to compare, again?

 

But as general principles:

 

• ISO is ISO - an ISO 100 color slide film, an ISO 100 color neg film, an ISO 100 B&W slide film, and an ISO 100 B&W negative film should produce "equal" exposures, with the same lighting, shutter speed and aperture.

 

• Color films will generally have more grain at a given ISO than B&W films. Just as an M240 at ISO 800 will have more noise than an M246 Monochrom at ISO 800. There is a cost in quality, to get the same brightness, due to the color-capture filtering, in either film or on sensors. Roughly speaking, an ISO 400 color film will have the grain of an ISO 800-1600 B&W film (depends on how good the company's chemists are).

 

• Slide films always have less latitude or DR than negative films. That is not required by the process, it is required by the fact that most people would find a slide with gray blacks and gray whites unpleasant-looking (unless the subject was a foggy day). So slide films (and the E6/K-14 processes) are intentionally engineered to produce pure blacks and whites, clipping the DR. The slide is the final picture, and must include all the tones from black to white - a negative (color or B&W) is just a step in the process, and thus can have a lower contrast, Dmax and Dmin - which look ugly on their own, but produce more DR once printed or scanned to a positive.

 

Kodak used to make an E6 slide-duplicating film 5071 (ISO 6-8) with an extra-large dynamic range, since it was intended to be used for photographing contrasty slides to make identical copies. Used for normal photography, it looked weird and dull (not counting the blue cast - balanced for light bulbs, not flash or daylight). https://farm8.static.flickr.com/7565/26844990146_6bf96ed5c3_b.jpg

 

So color slides could have more DR than they usually did - but it was not what most people wanted. Certainly not Ernst Haas, who did love his punchy Kodachrome slides, even if his shadows went inky black: http://fadedandblurred.com/wp-content/uploads/2014/05/ernst-haas-featured-2.jpg

 

I never shot enough Scala to know if it had more DR than 5071, or Provia, or Velvia, or E100VS.  But if so, that is not because it was B&W as such, it was because that is how the Agfa chemists chose to engineer the proprietary process and fim. It did certainly have less noise and more DR than an ISO 400 color slide film.

 

As to the add-on M8 IR filters - well, yes, those were denser than Leica's sensor filters. That was kind of the point - the Leica sensor filter blocked too little IR light. But what is on an M9 or M240 or M10 sensor is still far less dense than those external filters. I believe the M9 filter was only 40% thicker/denser (0.7mm vs. 0.5mm). And most of that only in the IR band. Transparent to blue, green, and most visible red

Edited March 3, 2017 by adan