Observation 21668: Leptogium lichenoides (L.) Zahlbr.

When: 2009-05-28

Collection location: Vavenby Limestone South, British Columbia, Canada [Click for map]

Who: Jason Hollinger (jason)

Specimen available

Among mosses on limestone rocks and cliff. The erect, wildly-laciniate lobes are nearly impossible to photograph without good depth of field.



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Photos through dissecting scope
By: Jason Hollinger (jason)
2009-06-09 13:42:25 AST (-0400)

These calibrate very accurately for me (between 0.5 and 1.0% accuracy according to my cursory tests). The way I take pictures through the eyepice is to focus at infinity in manual-focus mode — this blows up the central region of the image on the display so I can see whether it’s in focus (more or less) — then focus the microscope. Of course, I have to calibrate the resulting pixels/mm ratio for each combo of objective and camera. Then I just create a set of tiny images with the 1mm bracket on it at the appropriate sizes and overlay them onto my raw images before resizing thtm.

Thanks to Amadej for suggesting the approach.

It’s a bit less accurate without the dissecting scope: I took a dozen shots of a ruler in various poses and angles, focusing as close as the camera would let me. The resulting photos were all within about 3% - 42.5 +/ 1.3 pixels per millimeter.

Bear in mind, too, that only the features in the focal plane are actually the given size.

Great photos!
By: Daniel B. Wheeler (Tuberale)
2009-06-09 12:31:55 AST (-0400)

So … how did you get that great 1mm bracket incorporated into the photos? Taken under a disecting microscope?

Created: 2009-06-04 04:50:21 AST (-0400)
Last modified: 2012-05-30 00:50:59 AST (-0400)
Viewed: 36 times, last viewed: 2018-07-16 03:45:08 AST (-0400)
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