A bismuth crystal

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billben74
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A bismuth crystal

#1 Post by billben74 » Sun Sep 17, 2017 1:21 pm

Hello all. Its another stich and stack job. About 1000 images, then cropped.
Bismuth is quite interesting. Its cheap, it melts at 271 deg C and forms very interesting oxides when it recrystalises.
It also forms very interesting shapes - step/almost south american pyramid like crystals.
At the moment I've had more luck with the oxides than the interesting shapes.

I may continue to play.

Anyway metals are hard to photograph (as are metallic insects). The reflections, especially from irregular sufaces cause highlight issues and worse still blur

I presume we simply have light rays bouncing around all over the place meaning the points a,b,c can come out as c,b,a (and indeed worse cab,cab,cab -> as in several points imaging at the same point).
Anyone who actually understands optics feel free to educate me. (Or even better give tips on reducing blur)

Lighting them evenly with a diffusing system - mine is cylinder of bubble-like packing foam, helps a lot with the highlights but the blur can still remain.

Still its all good fun.
Done with my x4 na 0.13 flourite, several LED flashlights on goosenecks, two light panels and the foam cylinder.
2017-09-16-21.56.25 ZS bismuthSmallcrystalSquare12Highx4na0.13 DMap_stitchSomeEditSharpLevels1024.jpg
2017-09-16-21.56.25 ZS bismuthSmallcrystalSquare12Highx4na0.13 DMap_stitchSomeEditSharpLevels1024.jpg (86.4 KiB) Viewed 2586 times

Francisco
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Re: Un bismuto cristal

#2 Post by Francisco » Sun Sep 17, 2017 2:05 pm

Nice and interesting

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zzffnn
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Re: A bismuth crystal

#3 Post by zzffnn » Sun Sep 17, 2017 2:19 pm

Billben74,

I don't know much about optical math. I am just curious and want to learn from you:

1) did you put diffusion material as close to subject as possible?

2) have you tried other diffusion materials and stacked them? Such such stacked Vellum paper: http://extreme-macro.co.uk/macro-diffusers/

3) have you tried diffusion at other angles and places, such as over light source to increase directionality? It is generally not used for macro (compared to diffusion close to subject), but maybe it helps to bring out your colors there?

Crystal shape/arrangement (which can be affected by how fast you heat/cool) may also affect iridescent colors. The structure of your bismuth crystal looks different than the common one I have seen.

But the photo itself looks pretty sharp.

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billben74
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Re: A bismuth crystal

#4 Post by billben74 » Sun Sep 17, 2017 6:25 pm

Thanks Francisco.

Thanks zzffnn.

I don't know much about optical math. I am just curious and want to learn from you:
Me neither....

1) did you put diffusion material as close to subject as possible?
Yes - it was a cylinder of Styrofoam wrapped around the subject and the lens held with sticky tape.

2) have you tried other diffusion materials and stacked them? Such such stacked Vellum paper: http://extreme-macro.co.uk/macro-diffusers
No but thanks to you I might now. I see your point about Vellum -> lets light through well but also scatters. interesting

3) have you tried diffusion at other angles and places, such as over light source to increase directionality? It is generally not used for macro (compared to diffusion close to subject), but maybe it helps to bring out your colors there?
over the light source - In the past yes, but I guess I figured out it wasn't as good as diffusing around the lens/subject.
I have also tried ping pong balls and shampoo bottle cut off. The shampoo bottle is good, but lets less light in. I find you generally want a lot of light to crisp images.

Crystal shape/arrangement (which can be affected by how fast you heat/cool) may also affect iridescent colors. The structure of your bismuth crystal looks different than the common one I have seen.

Indeed. I have about 200g to play with at the moment and I melt in sturdy egg cup in an old pan which has lost its handle - so I've repurposed.
I only had small volumes of the molton metal and I did see some evidence of staircase crystals, but the videos online I've seen use larger volumes than I have.
This may matter.
I want little crystals - but will try another melt at some point, maybe with slighly more and see if I get more staircase like stuff.
One does see a variery of colours.


But the photo itself looks pretty sharp
But this is the good one ;)
See here for a less good one
2017-09-16-21.56.25 ZS bismuthSmallcrystalx4na0.13 DMap1024.jpg
2017-09-16-21.56.25 ZS bismuthSmallcrystalx4na0.13 DMap1024.jpg (245.61 KiB) Viewed 2568 times
As you can see more blur. I think this is more reflective and I think the (interesting) texture is causing light rays to bounce around like crazy.

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billben74
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Re: A bismuth crystal

#5 Post by billben74 » Sun Sep 17, 2017 6:28 pm

Also the two cup shaped indentations are marks caused by some twizzers wilst picking up the still soft crystal.

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vasselle
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Re: A bismuth crystal

#6 Post by vasselle » Tue Sep 19, 2017 12:03 am

Bonjour
Jolie
Cordialement seb
Microscope Leitz Laborlux k
Boitier EOS 1200D + EOS 1100D

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