Circle of Confusion in Metadata

[AandW]

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I noticed while looking at the metadata of M10 pictures I uploaded to Smugmug it shows  ‘Circle of Confusion’ of 0.015mm.   It appear to always be about that value regardless of the lens I used.   I checked back over time and it records 0.015mm for the M (240) and 0.030 for the M9.  It also shows 0.030 for the Nikon D800.   With the M9 and D800 the info is not included prior to 2013 so I wonder if it is something Lightroom has inserted (all photos processed through Lightroom) or perhaps it just started to show the data at that time in Smugmug uploads.

 

I was wondering why the circle of confusion would be included in metadata?  Also, why it would be different between the M9 (0.030mm) and M10 (0.015) with the same lens?  If it relates to pixel density as opposed to the lens then why would the D800 show as 0.030 and not something smaller than the M10?  My D800 had an anti aliasing filter so perhaps that factors in.  Just curious.

[lct]

Dunno where it comes from but with such a DoF value it would be impossible to focus mere lenses like 90/2.8 or 75/2 in RF mode i suspect. 

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[tonyniev]

I do not understand the question, this is my smugmug info 

[01af]

I was wondering why the circle of confusion would be included in metadata? Also, why it would be different between the Leica M9 (0.030 mm) and M10 (0.015 mm) with the same lens?

Good question. It doesn't make any sense.

 

 

If it relates to pixel density as opposed to the lens then why would the Nikon D800 show as 0.030 and not something smaller than the M10?

The maximum circle-of-confusion diameter depends on neither the pixel density nor the lens, but on (1) the viewing size-to-distance ratio and (2) the sensor or film format. Parameter #1 is unknown so it's common to make a reasonable assumption about it and proceed from there. That leaves us with parameter #2—and for Leica M9, Leica M10, and Nikon D800, the maximum circle-of-confusion diameter is always the same 0.03 mm since all three are 35-mm-format cameras. For APS-C-format it would be 0.02 mm, and for Four-Thirds it would be 0.015 mm.

 

Still, it doesn't make any sense to record these values in the image's metadata. If any kind of post-processing or viewing software needed to know the max. COC—I'm not aware of any—then the former always could compute the latter from the sensor size (and possibly make its own assumptions about parameter #1 mentioned above). So I assume it's just an artifact created by Smugmug.

 

 

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Edited August 4, 2017 by 01af

[AandW]

Viewing Photo Info on Smugmug via a web browser, selecting 'More Info' at the bottom and scrolling down shows the 'Circle of Confusion' info.

 

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[lct]

Never got this on my Smugmug pics so far. Just a Lightroom (or M10?) brainless thing i suspect. 

[Bill W]

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I think I will choose to not worry about this in my metadata.

[FlashGordonPhotography]

I would suggest this is something SmugMug is adding. Incorrectly....

 

Gordon

[tonyniev]

not in my smug mug