Diamonds and nickel

[rjlittlefield]

This probably isn't what you were expecting to see(!), but I think it's interesting anyway.

This is a diamond sharpening stone from DMT, specified by them as "325 mesh, 45 micron".

Let's start very close and work back.

50X on sensor, most of the whole frame:



10X on sensor, resized to 50% of actual pixels and cropped:



10X on sensor, most of the whole frame:



4X on sensor, most of the whole frame:



The whole stone, set up for shooting at 50X:



Don't bother trying to find matching features between magnifications. I repositioned the stone to simplify focusing, so the pictures are of different areas.

Hope you enjoy!

--Rik

Technical: Canon T1i camera. Lenses were: 1) Nikon CF Plan 50X NA 0.55 ELWD inf/0 on Canon 55-200 mm zoom; 2-3) Nikon CFI60 10X NA 0.25, on same zoom; 4) AmScope Plan Achromat 4X NA 0.10 160/0.17 on extension tubes. Kleenex diffuser with flash at 50X, continuous for others. Stacked at 2 µm for 50X, 15 µm for 10X.

[DQE]

An interesting subject as well as a candidate for testing and comparing various setups.

Also an enjoyable abstract pattern in its own right.
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I also have a set of sharpening devices by this company but had never thought about using them for macro photography. (An aside - mine work very well for sharpening knives, etc). Perhaps if one marked a specific section of the device with some sort of sharp ink pen or something, a person could at least use it for his/her own comparative tests.

I wonder if they are standardized enough for use to use for comparing sharpness and detail of optics among the many forum members? I guess we would need to take photos of the same object at the same position for this to be of much use even if the particles were reasonably close in size and shape...better stick to resolution patterns of other fixed test patterns, I guess.

[rjlittlefield]

Phil, thanks for commenting.

Mostly I shot this thing because I was curious what it would look like. As often happens, direct viewing through a microscope was not very helpful. ("Oh, it looks a bit like finely ground black pepper!"). But the closer views were a lot more interesting.

As for using this subject as a standardized lens test, I'm still quite pessimistic about the general idea of comparing lenses based on anything besides direct head-to-head comparisons. Looking back over my own testing, I'm pretty comfortable that I can reproduce the ordering of lenses, A beats B beats C. But it's awfully easy for C today to look better than A did yesterday, because of unnoticed differences in the test setup and execution.

It is true, though, that part of this thread is vaguely associated with lens testing. As I've mentioned elsewhere, I'm on the hunt for an inexpensive new manufacture objective that I can recommend as a "known good" lens for use in the 4-5X range. I don't have enough data yet to post specifically on that topic, but it's worth noting that the 4X image shown above came from a lens whose list price is $50 and is often available on sale for $25. That's the finite AmScope 4X Plan Achromat (NA 0.10, 160/0.17). A current eBay reference is HERE.

--Rik

[JW]

Rik

Nice to see an example of both the irregular fracture and octahedral cleavage of diamond crystals, seems to be more fracture and less cleavage in this material - do you know if it is natural or articifical diamonds?

I am a bit confused, you are using a tube lens with a CF160 objective? I thought you only needed extension tubes for fixed focal length objectives.

Also, I see the purple fringe monster has appeared, especially around the highly diffractive edges of the diamond crystals - I usually see this also around the highlights in crystals when using my Nikon 10X inf/0 objective with the Canon 75/300 IS zoom lens - I know we discussed this previously, any thoughts on how to avoid or fix?

thanks, Jeff

[Pau]

Rik, interesting views. Most materials are surprising at high magnification

I am a bit confused, you are using a tube lens with a CF160 objective?

CFI 60, not CF 160.
CFI60 is the modern Nikon standard for infinite objectives.

[JW]

Pau

thanks for the clarification, to quote Emily Litella "Never Mind!"

[naturephoto1]

Pau

thanks for the clarification, to quote Emily Litella "Never Mind!"

A Gilda Radner fan I see; what a loss.

Rich

[rjlittlefield]

Nice to see an example of both the irregular fracture and octahedral cleavage of diamond crystals, seems to be more fracture and less cleavage in this material - do you know if it is natural or articifical diamonds?

I expect these are synthetic industrial diamonds -- lots of impurities but still pretty hard, able to be manufactured cheaply and in large quantity.

Also, I see the purple fringe monster has appeared, especially around the highly diffractive edges of the diamond crystals - I usually see this also around the highlights in crystals when using my Nikon 10X inf/0 objective with the Canon 75/300 IS zoom lens - I know we discussed this previously, any thoughts on how to avoid or fix?

No, I don't know how to kill this type of CA, short of desaturating it in post-processing. I tried that, but I didn't like the appearance so I left it alone.

Fortunately, there's a lot less color in the stacked result than there is in the source images. Here is a comparison of that aspect, with the same levels and curves adjustments applied to both:



--Rik

[harisA]

Rik

.

Also, I see the purple fringe monster has appeared, especially around the highly diffractive edges of the diamond crystals - I usually see this also around the highlights in crystals when using my Nikon 10X inf/0 objective with the Canon 75/300 IS zoom lens - I know we discussed this previously, any thoughts on how to avoid or fix?

thanks, Jeff

It's a common problem with shiny objects with sharp edges...The following procedure works for me most of the times

http://www.outdooreyes.com/photo26.php3

[JW]

harisA

thanks for the tip. I found that by pushing the saturation slider to max, the selection of the purple fringe and its color range is much easier, and you can tell if any parts of the image amy be negatively impacted.