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Leica 90mm images


Ouroboros

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On 6/13/2020 at 11:30 AM, Ouroboros said:

Nimrod.

Leica MP

90mm elmarit-m f2.8

T-Max 100

Heliopan 22

 

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A wonderful capture of a beautiful aircraft.

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Next-door neighbour's new toy...  90mm Summarit f2.4 on M10M.  (click to view in LightBox).

 

 

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On 6/17/2020 at 3:59 AM, tedd said:

Lightroom says f4. That may or may not be right, I still can't work out how it knows!

To expand a bit on ianman's brief-but-correct response above:

Leica M digitals have an external meter that reads the overall scene brightness in front of the camera (little circular sensor on the front near the shutter dial). The external meter does nothing to set the exposure - it is strictly a reference meter for estimating the aperture used and other things (setting the brightness of the frameline illumination LED so that framelines are not too dark or bright, removing aperture-dependent vignetting)

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The CPU compares that direct scene brightness reading with the amount of light actually reaching the internal exposure meter (which is darker or lighter according to the aperture setting) and uses the difference to estimate the aperture in use. This estimate is recorded in the picture file as metadata when the picture is saved to the SD card, which LR or other computer software can read.

It is also used by the camera to make corrections for optical vignetting (dark corners). Which is usually more extreme at larger apertures, thus the camera needs to make at least a good guess as to whether you were using f/1.4 or f/4 or f/8 or f/16.

There are anomalies in the estimate: focal length (what the lens is projecting vs. what the fixed field of the external sensor (~50mm?) is measuring). The estimate can be off by up to ±2 stops due to the placement of tones within the picture area (e.g. dark trousers or a white shirt), and it is rather common for a picture made at, say, f/2.8, to be recorded as f/3.4 or f/4 or f/2.4.

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  • 2 weeks later...

Passing traffic...  90mm Summarit-M f2.4 on M10M. 

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Edited by Keith (M)
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