Grape Chalcedony by Macro Cosmos (DH)
Bigger version on Flickr.
Taken with the Laowa 25mm. I'd love to hear some advice on lighting, this is my current setup:
Diffusion provided by some plasticy-thingy bought at Ikea. DIY diffusion box made from those metal book holders.
Any advice is greatly appreciated! I find this to be harder than 1:2 and 1:1 settings, a lot harder with lower tolerances of failure.
"Grape Agate", Grape-Like Chalcedony
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It was called grape agate initially, which some people still call it that.soldevilla wrote:Are you sure that this is chalcedony? They look balls of fluorite.
Chalcedony is microcrystalline, never shows crystals, and quartz is not cubic.
Most people on sites like mindat call it chalcedony now, I am not a mineralogist expert and I just go where the popular opinion goes.
https://www.mindat.org/min-51479.html
I do not think it is fluorite though. Fluorite has a very distinct look, these are actually individual clusters not attached to any kind of matrix.
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Re: "Grape Agate", Grape-Like Chalcedony
What you have looks pretty good, but I think you could do even better with a different diffusion material.Macro_Cosmos wrote:I'd love to hear some advice on lighting, this is my current setup:
The reason is that I can discern your holding structure by looking in through the diffuser. That implies that your subject can discern your lights, which means that your diffuser really isn't diffusing very well, which leads to overly bright specular highlights.
I suggest substituting some thin paper in place of the plastic bubble sheets.
See http://www.photomacrography.net/forum/v ... 7343#37343 and the couple of posts after that for a quick comparison of plastic bubbles and paper for effectiveness of diffusion. Postings #1 and #3 of that thread, at http://www.photomacrography.net/forum/v ... php?t=6090, show the effect of photographing the same subject with two different qualities of diffusion.
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I know the grape agate (I do not have a sample in my collection, but it will arrive soon, I hope)Macro_Cosmos wrote: It was called grape agate initially, which some people still call it that.
Most people on sites like mindat call it chalcedony now, I am not a mineralogist expert and I just go where the popular opinion goes.
https://www.mindat.org/min-51479.html
I show a fluorite "ball" that really is a group of cubes. It was collected by me (yes, this piece is in my collection).
Fluorite has a very special diffraction index, which makes it difficult to illuminate. I think I used a disposable plastic cup of coffee, as a diffuser. If you try it, take a white balance because there are plastic cups that introduce a reddish dominant.
This material and its nature has been extensively discussed over at mindat.org
It is quartz, although chalcedony or some other variety may not be appropriate.
Its easy enough to test, fluorite is relatively soft and quartz is much harder.
It is quartz, although chalcedony or some other variety may not be appropriate.
Its easy enough to test, fluorite is relatively soft and quartz is much harder.
It's not what you look at that matters, it's what you see - Henry David Thoreau