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M9 ISO Performance - New Life


colonel

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Tell me if I am wrong. The sensor only works at base iso. All other settings are amplified by the camera electronics.

 

Should I be surprised a computer can amplify with less noise than a crumby small amp in the camera?

 

I don't fully understand how it works but at some point the signal to noise ratio of the amplifier exceeds what can be done in software. Here is a good article:

ETTR — just crank up the ISO? Not so fast. | The Last Word

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Yes I know this has been a much discussed topic and most of the talk has shifted to the M240, however Lightroom since version 3.6, boosted again by 4 has made the M9 good at 2500....

 

As you say, this has been a much discussed topic, and I think instinctively many of us have been doing this in post anyway.

 

What I'm curious to see though is the impact on dynamic range and colour saturation... Are they impacted less through post or through in-camera ISO increase, and to what extent I wonder...

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What I'm curious to see though is the impact on dynamic range and colour saturation... Are they impacted less through post or through in-camera ISO increase, and to what extent I wonder...

 

Because Lr's PV2012 compresses (like film), rather than clips highlights as the internal amplifiers do, pushing in post will give greater dynamic range -- you will have usable output over a greater range of light levels.

 

Outside the region of compression, I've not found any effect on color saturation. Within the region of compression, saturation is reduced. Of course, clipping reduces saturation, as well as causing color shifts if one or two channels clip before the third.

 

The M240 is an exception to the statement about color saturation. Because of nonlinearities at extremely low signal levels at ISOs of 200, 400, and 800, pushing M240 raw images made at those ISOs in post can result in shadow casts (usually green), and loss of saturation as the red and blue raw channels are depressed.

 

Jim

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Under exposing and pushing in post will give similar results as film in that the highlights are pushed more compared to the shadows and you end up with a more contrasty image than if you crank up the ISO in camera. I prefer this look for nighttime shots since it feels more real, but be careful when you shoot portraits etc. - you can quickly end up with harsh looking skin tones and dark eye sockets.

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This technique works well and gets around the amplifier design points for read noise (possibly Leica uses two stages of amplification over ISO 640 and one stage 640 and lower).

 

Another thing to consider, when using manual exposure, is to use Auto ISO with the max ISO set to 640. This will help you when your are shooting a scene that you "think" should be set to manual exposure and 640 max, however is slightly brighter than anticipated. In these cases, the lightmeter might pull the iso downward, which should be of some benefit to pull back highlights. If the scene is darker than the "nominal exposure", the auto iso feature will be limited to 640 max. This is the way I shoot "low light", with usable results to an equivalent of ISO 6400.

Edited by TonyField
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Under exposing and pushing in post will give similar results as film in that the highlights are pushed more compared to the shadows and you end up with a more contrasty image than if you crank up the ISO in camera. I prefer this look for nighttime shots since it feels more real, but be careful when you shoot portraits etc. - you can quickly end up with harsh looking skin tones and dark eye sockets.

 

Let's make sure we're talking about the same thing. I'm talking about pushing raw files. Pushing JPEGs very far usually ends in tears. Also, I"m talking about Lr PV2010 and PV2012. Although I've seen similar results with other raw converters, it will greatly clarify the discussion if we can settle on a few.

 

That said, it has been my experience that. wrt contrast, PV2010 Exposure control moves rather faithfully mimic what you'd see by making equivalent adjustments to the in-camera ISO control, and that PV2012 performs much the same in the linear region, and actually reduces contrast in the highlights.

 

Proof?

 

If you're a visual person, take a look here. These are D800E images, and were made to illustrate noise performance, but they can yield contrast information as well. Here is a similar series with the M9.

 

If you want to see M240 images, green shadows and all, look here and here.

 

If you have more of an analytical bent, look here.

 

Jim

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Jim, I am inclined to agree, to a degree, with Bernd -- I think there is an apparent "visual contrast" increase when you push the images. This can easily be corrected in ACR (and I assume Lightroom - since it uses the same engine) using the "contrast" slider.

 

Here is a set of images. The first one is "metered at ISO 640". With manual exposure, each image receives 1 stop less exposure and therefore requires 1 stop more compensation in ACR. The top numbers indicate the "push value" in stops using ACR. I read this as a slight contrast increase which seems noticeable in the face and body. But maybe my eyes ain't so hot :) Possibly the apparent change in contrast might be due to the reduced DR ?? The shots are with the F1.0 Noctilux, left to right, at F2.0, 2.8, 4, 5.6.

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Edited by TonyField
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Jim,. I read this as a slight contrast increase which seems noticeable in the face and body. But maybe my eyes ain't so hot :) Possibly the apparent change in contrast might be due to the reduced DR ?? The shots are with the F1.0 Noctilux, left to right, at F2.0, 2.8, 4, 5.6.

Does the aperture change affect contrast?

Pete

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Yes I know this has been a much discussed topic and most of the talk has shifted to the M240, however Lightroom since version 3.6, boosted again by 4 has made the M9 good at 2500.

 

Of course the reason was well known, low CPU power, virtually no image processing by Leica on RAW means that you use your PC power to make the JPGs, as the software has become better the M9 effectively becomes a new camera.

 

Recently I learned (or bothered to learn) a new technique where you shoot at 640 and push post, anything 1-3 stops is normally fine depending on the exact scene. This is based on research on the M9 saying that 640 and above the current computer CPUs and software pull away radically from the M9's capability. Actually this is the same, give or take, with all cameras, but particularly with the M9 (and M8) due to Leica's approach.

 

How to do this is mentioned elsewhere but basically you set the aperture as large as you can and the speed as low as you can dependent on scene (e.g. f3.4, 1/30) and just take on 640, brightening later in Lightroom. Probably old stuff to many of you but the results done this way can be very clean. Its also very fast as you just make small adjustments to the aperture or speed if needed (based on static or moving subjects) and can leave metering behind until PP.

 

Some recent examples, as good or almost as good as my 6D or D800E could do.

 

Doesn't this information serve two purposes?

 

First and foremost making M8/9 owners feel good by getting an improvement from Adobe for the files of our trusted and paid-off digital M cameras.

 

And isn't it an additional reason to set the eyes now on a new M 240 with its faster buffer?

Having taken three shots with bracketed exposures (one for processing at "real" ISO, one under-exposed by 2-4 stops according to this method and a third under-exposed even more for future versions of Lightroom)?

And right afterwards being ready for the next burst of three DNGs, as with any a modern camera :) .

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Jim, I am inclined to agree, to a degree, with Bernd -- I think there is an apparent "visual contrast" increase when you push the images. This can easily be corrected in ACR (and I assume Lightroom - since it uses the same engine) using the "contrast" slider.

 

...The shots are with the F1.0 Noctilux, left to right, at F2.0, 2.8, 4, 5.6.

 

Tony, by varying the aperture, you allow for the possibility that some or all of the contrast differences could be the result of veiling flare that decreases as the lens is stopped down. Can you run your test again with shutter speed as the variable?

 

For my part, I will do a similar series using subject matter that, although less appealing, admits to easy measurement.

 

L1001231.jpg

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Very cool. Most of the time when I need high ISO it's situations where I actually want some noise/grain, but there are those times where it isn't. Your interior shots recall one of those situations. And there are even some daytime shots where I want both a higher shutter speed and smaller aperture and don't want the grain effect, so this technique would be perfect for that. I just now updated LR from 3.2 to 3.6. Now I'm even less in a hurry to get an M240.

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bocaburger, you may want to upgrade to LR4, or better yet, LR5. They both have Process PV2012, which, as Jim Kasson states above, compresses like film rather than clipping highlights — a big improvement over PV2010. LR5 has a new Rdial Filter tool that is very good for dodging and burning.

 

—Mitch/Paris

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On a similar "push processing" theme, the M9 is virtually ISO-less. I always find it amazing how you can recover under-exposed images with a three and sometimes four stop exposure error. Sometimes you forget to "lock exposure" between shots :)

 

The last image is "properly locked" with no compensation in ACR. I forgot to lock exposure on the first shot and it is still recoverable :)

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Edited by TonyField
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