GEAR TALK - Maximizing the Leica M-P Type 240 High ISO Performance

There are different approaches to shooting a camera's upper ISOs, especially if using an ISO invariant camera. What is an ISO invariant camera? Long story short - the sensor is always at base ISO regardless of the ISO set. Instead of using hardware amplification to boost sensitivity, the the camera purposely underexposes (intentionally) to boost shutter speed as ISO is increased. The camera then applies a tone curve to increase image brightness. For more about ISO invariance - click here.

Some people prefer to leave the camera at base ISO and increase the shutter speed one stop rather than boosting ISO one stop. In turn, during post processing they will increase the exposure compensation 1 stop. The working theory being that the respective RAW editor can do a cleaner boost than the in-camera programming. But since the image was grossly under-exposed, the in-camera image review is worthless - it will be just be a very dark frame...

I prefer to use in-camera ISO because that generates a usable image on the camera's rear LCD where I can judge the histogram, check sharpness, etc. The downside in an ISO invariant camera (like the Leica M Type 240), each one stop increase in ISO generally translates into one stop of dynamic range lost. This means highlights can be blown easier, thus I expose for highlights and open up the shadow areas in post. While taking the pictures, if exposure look too dark, I will increase exposure compensation (EC) and re-shoot.

Exposing for highlights and shooting high ISO usually require the dark areas to be boosted in post production (I use Capture One). Boosting shadows can be done via shadow recovery, levels edits, curves edits, brightness edits, etc. All do essentially the same the thing - raise luminance values. Raising the luminance reveals the underlying nastiness - chromatic noise, luminance noise, pattern noise, confetti noise, hot pixels, color casts, blotchiness, banding, mazing, cross-hatch patterns... Most raw editors do a good job suppressing hot pixels, chroma noise and luminance noise. But pattern noise is a trickier animal. My silver bullet is NIK's Dfine noise reduction plug in (for Photoshop). NIK's debanding option is sort of hidden -

Click to See Full Screenshot

To select the debanding option - click "Reduce", then click the "More" arrow and tick the "Debanding" check box. There are additional settings to vary the amount of color and luminance noise reduction - I usually back these off to ~25% because my goal is to eliminate banding without sacrificing detail. Savvy Photoshop jockeys will mask in the noise reduction, probably run some additional noise reduction to clean up trouble areas, mask that in, and so forth. Using NIK's built-in "Control Points" functionality is another option as well (their version of selective editing).

50% Crop of Before & After with NIK's Debanding Applied

In the sample above the NIK "Reduce" settings were 25% contrast, 33% color, 20% preserve edges and debanding enabled. Noise reduction is always a balance between retaining detail vs smoothing out noise. In this case much of texture (details) remains in tact, but horizontal banding is mostly eliminated. This sample was boosted with brightness and shadow recovery for illustration purposes. In the actual edited image (at the top of page), this particular area is darker so the remaining banding is not visible.

Knowing that I get workable high ISO file from the Leica M-P (240) has encouraged me to shoot in low light condition where I previously would not have bothered. This page has a range of examples from different cameras where Dfine was used as part of the post processing treatment.