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M10M True Base Iso


shirubadanieru

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Hi everyone, reidreviews just tested the M10M (true) base ISO, and it seems to be somewhere between ISO 400 ~ 640. My camera will finally arrive tomorrow so I'll be probably shooting it at ISO 400 by default after reading his review. If you have a subscription, there's way more details about this in the article; for those who don't subscribe my advice would be to keep it at ISO 400 if you want to retain most DR and highlight info, as per reidreviews testing. Just think of it as shooting HP5 or Tri-x, but instead of metering for the shadows, meter for the highlights : )

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Guest Nowhereman

Interesting. Also interesting that some reviewers reported, and praised, the camera for having 160 as the base ISO. Shows how much you can trust those early reviews. Why would Leica not make this information available themselves? Schlock marketing? Just looking at the example images that Leica made available doesn't indicate good marketing.

As I recall, some of the early M10M buyers had issues with the tendency of blowing highlights: I suppose that could have been because they were shooting at ISO 160 rather than at ISO 400 — similar to the introduction of the M10, before people realized that the base ISO of that camera was base ISO was  loser to ISO 200 and not ISO 100. These issues, both at the introduction of the M10 and the M10M, it seems to me, could have been avoided had Leica simply stated in the spec sheet what the base ISO was. Or am I wrong on this?
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Issues with stating a "base ISO."

1) It is not all that well-defined. Reid says "somewhere between 400 and 640," and for the original M10, Stefan Daniels said "somewhere between 125 and 160." And if Reid (a great tester) and Leica themselves can't be sure of what it is, how can Leica "state" anything sensible - or accurate?

2) How do you put "somewhere between..." onto a physical ISO dial, or even into a menu list?

3) Bottom line, the base ISO of a sensor is a case of "cut once, measure twice." Or in another analogy, "throw darts at a blank wall - and then draw a bullseye around wherever most of the darts land."

You forge the silicon, and likely have a rough theoretical idea (a narrow range) of what the quantum physics will deliver as a base ISO. Then you test the silicon, and get some number (ISO "132" or ISO "447"). And then you adjust the processing algorithms to normalize that to the nearest "almost base" ISO that fits the classic 1/3rd-stop progression (e.g. 100, 125, 160, 200, 250, 320, 400....)

Leica could, of course, produce an ISO dial or menu that reads "132, 169, 211, 264, 338, 422...." etc. Except they'd need a whole slew of dials and firmware versions, because some sensors would come off the line with an actual base ISO of 130, and others with a base ISO of 137 and others with a base ISO of 134 (quantum physics and the uncertainty principle - again). H*ll, individual pixels on a sensor probably vary at least that much in their exact response to light.

(Back in the day, Kodak used to test every batch of Vericolor I/II/III Professional 4x5 (or 120 or 35mm) film (nominally ISO 160). And each box would get its own instruction sheet, with the actual tested ISO (but still rounded up/down) overprinted in red, e.g. ISO 160, ISO 125, ISO 200, (plus unique color-filtering corrections for printing each batch, e.g. +05M(agenta)) - and photographers would adjust their handheld meters and their enlarger filter packs accordingly. But the equivalent with digital controls would mean different knobs and/or different firmware menus custom-programmed for each and every body/sensor. Really?)

Bottom bottom line - The difference between the DR of a given sensor shot at ISO 400 and, say, ISO 422 will not be demonstrable outside a fairly sophisticated laboratory. We're talking 1/6th of a stop - can you even set your aperture ring or shutter speed that precisely?

 

 

Edited by adan
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2 hours ago, shirubadanieru said:

 Just think of it as shooting HP5 or Tri-x, but instead of metering for the shadows, meter for the highlights : )

Film speed tests typically prompted me to rate Tri-X at 250, give or take.  I liken Monochrom use to shooting slide film; watch the highlights. In any event, blown highlights are more of a user thing than a film or camera thing... know thy tools.  And know thy own style: I’d often rather have blacks go black than worry about opening up shadows and showing off dynamic range.  Each picture demands its own treatment, and that flexibility is one of the advantages of digital over film.

Jeff

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1 hour ago, adan said:

Bottom bottom line - The difference between the DR of a given sensor shot at ISO 400 and, say, ISO 422 will not be demonstrable outside a fairly sophisticated laboratory. We're talking 1/6th of a stop - can you even set your aperture ring or shutter speed that precisely?

 

 

luckily this is not in the SL thread ;) those threads would carry on forever with DR/test shots :)

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I am waiting for Bill Claff's measurements (photonstophotos.com) before I can understand the full picture of ISO behavior on M10M. If Bill's analyses show that the dynamic range is better at lower ISOs (ISO < 400), then it may still make sense to use lower ISOs while applying negative exposure compensation (similarly to what is happening with Q2 with ISO 50).

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With almost 41 MP the M10M sensor is able to gather much more light than the previous 24 MP sensor in the 246. If ISO 320 was the base ISO for the 246, then it seems to be obvious, that the M10M has an even higher base ISO. My guess is, that it will be above 500, resp. between 500 and 640.  Maybe a few of us, me included, must give up old thinking from film days, when 50 or 100 ASA Films delivered the best image results with lowest grain.

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Not sure I understand this. Is the OP saying that the M10M’s base ISO is actually 400ish and that the settings of 100 and 200 are actually pulled in firmware thereby degrading quality or is it that the setting of 100 on an M10M is comparable to 400 on a light meter? 

If the former, as I read the post, then this really would make little sense. Why would Leica degrade their image quality by listing ISO 100 and 200 as true base ISOs and not pulled ones? 

Edited by AceVentura1986
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8 minutes ago, AceVentura1986 said:

Not sure I understand this. Is the OP saying that the M10M’s base ISO is actually 400ish and that the settings of 100 and 200 are actually pulled in firmware thereby degrading quality or is it that the setting of 100 on an M10M is comparable to 400 on a light meter? 

If the former, as I read the post, then this really would make little sense. Why would Leica degrade their image quality by listing ISO 100 and 200 as true base ISOs and not pulled ones? 

It says that true ISO is 400ish and that 160~320 seem to be pull settings. the quality is not that reduced looking at the testing to be honest, so I'd be comfortable shooting at 160 if required, but ISO between 400~640 show less highlights clipping.

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One can blow highlights at any ISO as I have unashamedly discovered in my “working” this camera. I call this M10M a Hyper Camera and like any performance equipment there are ways an operator must learn to get the most from it. 
 

I love the results at 160 ISO and also at 10,000. I never used the 160 Pulled iso of MM1, it is pretty crap but not so with the M10M. 
 

 

 

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1 hour ago, Jager said:

Rather like suggesting that a car has a propensity to drive off bridges.

Would you say that a Jeep Wrangler has the same cornering ability as, for example, a Lamborghini?

I did a little testing of the "highlight cornering ability" of the basic M10 compared to the M240 - the M10 tends to blow straight through "255" a little more steeply than the 240. Its highlights aren't blown - until suddenly they are. The 240 sneaks up on "255" with a shallower curve. (BTW, still waiting to find a CCD Leica to add to my data. And, for that matter, the various flavors of Monochrom).

That is not strictly a characteristic of the silicon. It also depends on the tone-curve set in the firmware by Leica. But unless you can hot-rod a camera by writing your own firmware, it is a built-in camera characteristic that comes in the box.

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41 minutes ago, adan said:

Would you say that a Jeep Wrangler has the same cornering ability as, for example, a Lamborghini?

 

 

The point, though, is that the driver is responsible, not the car. And the driver must be wise enough to understand the difference, without having an automotive degree.  Proceed slowly to learn behaviors, and use common sense. Some who can afford Lamborghinis have more money than common sense.  

Jeff

 

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Interesting thread and food for thought.  I'm a few days into getting to grips with my M10M (first Monochrom), have the camera in 'A' mode and ISO set to Auto.  In my limited outings so far (hampered by Storm Ciara) I have set exposure comp to -0.3 (which I always do with my M240 anyway) with an occasional  -0.7 dialled in.  Looking at the exif for my typical landscape-type photos, ISO is shown as mostly 160 and highlights are not being blown.  Next outing I'll try 400 and possibly 800.  (The dial has hard stops at the designated numbers and intermediate settings (i.e. 640) are not selectable).

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vor 3 Minuten schrieb Keith (M):

 Next outing I'll try 400 and possibly 800.  (The dial has hard stops at the designated numbers and intermediate settings (i.e. 640) are not selectable).

Why don`t you go into the menu. You don`t need to use the dial. In the menu you should find more variables. 

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