Wulfenite on Mimetite

[physicsmajor]

Thumbnail size specimen of Wulfenite on Mimetite from the Rowley mine, Maricopa county, AZ. A few chips and broken corners but the overall specimen is quite nice.

After Robert's recent article where he found the Scanner-Nikkor ED 7 element lens did quite well at 1.4x I took another look at this lens, made a setup for exactly this magnification using a spare F-mount adapter and Thorlabs SM2 tube to my D7000. I've been quite happy with the results! Lets my Minolta 5400 become dedicated to the 2-3x range where it really shines, and the extra light allows faster shutter speeds, always appreciated given my continuous lighting setup with the rail on a tripod.

Overhead high-CRI lighting with a diffuser, further diffused by a curved sheet of paper.

Here is an (actual) crossed-eye stereo pair, which I cannot see but I understand most people can:

And a parallel stereo pair (magic eye), which is the only way I can see stereo images:

The 'closest' part of the image should be the bottom center. Whichever of the above appears that way to you is correct.

Stacked with Zerene, I used the built-in slabbing as this stack was nearly 200 images. PMax, 16 shots per slab, 4 overlap worked nicely for the main shot which were then combined with both methods, DMap used as base and cleaned up with PMax. The 3D views were straight PMax of the original images to get proper stereo effect, and thus have a mild amount of noise in the originals which is completely gone at this greater than 9-fold reduction.

[jurkovicovic]

Beautiful specimen! It is always tragedy when some part or specimen is broken
Picture looks really good. For me it is too much red, maybe too much saturation?
Good job!

[rjlittlefield]

Nice job! Stereos came out well. I need a viewer for the parallel pair, because my eyes do not naturally diverge and I've never trained them to do that.

--Rik

[physicsmajor]

In the interest of full disclosure, I generally run my images through Perfectly Clear 3.5. However, I strive to use this for whole-image correction closer to actual color/what I see through the viewfinder rather than to apply something like an Instagram filter. I do not change the color balance.

This is the image directly off the D7000, with white balance Kelvin matching my continuous high-CRI LED source. It has been stacked but no other postprocessing whatsoever (including sharpening - linear mode downsampling in GIMP).

This particular specimen viewed in natural light does appear a bit on the orange/red side relatively to some other specimens from the same location.

I don't think I have been dishonest in terms of postprocessing - but you be the judge!

[Scarodactyl]

Wulfenite just has that look, or at least can. Classic Red Cloud material as an example is as saturated as can be.

[JW]

Usually the mimetite from Rowley is more yellow rather than the orange in your image, and the highlights off of the wulfenite crystals seem a bit too reddish to me. Getting accurate color balance with a black background can be tricky sometimes. A quick auto color correction in PS resulted in a much more realistic image to me - not posting as I don't have the original to compare against; I'd suggest playing around with some PS controls and see if the appearance is improved.

[rjlittlefield]

Getting accurate color balance even with a gray reference can be difficult sometimes.

The problem is due to an effect called "metamerism". Very briefly, the camera sensor has a different spectral response from human eyes, so it can see some materials quite differently from a human, even when it sees a gray reference as being the same. See panel 3 at http://www.photomacrography.net/forum/v ... 42#p234842 for a particularly nasty case of the camera seeing way too much red compared to my own eyes.

I have no familiarity with wulfenite or mimetite, but in general I'm a fan of manual adjustment so that screen image matches visual appearance.

--Rik