Volcanic Glass

Images taken in a controlled environment or with a posed subject. All subject types.

Moderators: Pau, rjlittlefield, ChrisR, Chris S.

RoxnDox
Posts: 16
Joined: Tue Mar 31, 2020 4:17 pm
Location: Somewhere near Seattle

Volcanic Glass

Post by RoxnDox »

Another of my lava samples from the 2018 Kilauea eruption. This time it was seeing what I could get with a piece of tephra - the very light, very fragile ejecta that is shot up in the air from the lava fountains, cools very rapidly, and falls like ash everywhere in the area. It's so light because the gasses in the lava expand as it goes up, forming bubbles and a foamy structure. The lava is cooled off so quickly it doesn't have time for the atoms to aggregate into minerals, so it turns into a volcanic glass sort of like obsidian... When I got the pictures on the big computer screen, it was amazing the details of the structure shown. Madam Pele does some real artistry!

Pentax K-50, Tamron 90mm Macro, 4 images combined in Focus Stacker.

Image
I go by "Jim" in real life, "RoxnDox" on here...

leonardturner
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Joined: Thu Mar 14, 2013 11:40 am
Location: Atlanta, GA, USA

Re: Volcanic Glass

Post by leonardturner »

An intriguing image; I'd be interested is seeing others of this subject, perhaps at higher magnification!

Leonard

Pau
Site Admin
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Re: Volcanic Glass

Post by Pau »

Very nice subject and image.

I wonder if you could be able to show a deeper stack, a stereo pair also would be most enjoyable
Pau

RoxnDox
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Joined: Tue Mar 31, 2020 4:17 pm
Location: Somewhere near Seattle

Re: Volcanic Glass

Post by RoxnDox »

Pau wrote:
Sat Nov 21, 2020 11:17 am
Very nice subject and image.

I wonder if you could be able to show a deeper stack, a stereo pair also would be most enjoyable
Thank you :) If I can find that particular spot again (that bit took some damage) I can try for a deeper stack. At this stage in my (very beginning) skill level I would have no idea how to make a stereo pair, and I suspect it would require some gear I don't possess... Yet. Maybe. :-k
leonardturner wrote:
Sat Nov 21, 2020 4:12 am
An intriguing image; I'd be interested is seeing others of this subject, perhaps at higher magnification!

Leonard
Thank you as well! I do have some more images, not all of this piece but from the same box of lava bits... This particular piece has been crumbled some from accidental contact with the other bits, and I'm not sure this part survived, but there should be lots more to try. As to higher magnification, this is the best I can get with my current gear. I've not gone down the rabbit hole of trying extension tubes or reversing rings, and the budget-conscious brain cell says no to another lens... They look pretty nice on my 27" Mac at 100%, though :) This is another fragment at 100%, less structure but nice colors.
Image

This one is a 100% crop from yet another fragment with wonderful iridescent colors, FOV is around 10mm(ish), 8 frames combined in Focus Stacker. Best I can achieve right now, I think.
Image
I go by "Jim" in real life, "RoxnDox" on here...

leonardturner
Posts: 613
Joined: Thu Mar 14, 2013 11:40 am
Location: Atlanta, GA, USA

Re: Volcanic Glass

Post by leonardturner »

Very nice; I particularly like the second image in your re-post.

Leonard

RoxnDox
Posts: 16
Joined: Tue Mar 31, 2020 4:17 pm
Location: Somewhere near Seattle

Re: Volcanic Glass

Post by RoxnDox »

I did manage a bit more magnification, and a deeper stack today. My wife's camera kit has an old 1.4 TC (late '70s vintage) that I'd forgotten about, so I can get 126mm at the cost of some image quality. This one is a 15 frame stack, but it looks like I pushed Focus Stacker past its limits in the corners. The areas where it worked, however, do show the 3 dimensional structure. Interestingly, this fragment has quite a few of the gaps spanned by glass films. Those made lighting a bit more challenging because of too many reflections from the direct light of my desk lamp 'spotlight', so it is bounced off the side wall of the light box for this set. I tweaked the sharpness somewhat in gimp.

Field of view is approximately 3mm.

Image
I go by "Jim" in real life, "RoxnDox" on here...

RoxnDox
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Joined: Tue Mar 31, 2020 4:17 pm
Location: Somewhere near Seattle

Re: Volcanic Glass

Post by RoxnDox »

leonardturner wrote:
Mon Nov 23, 2020 4:43 am
Very nice; I particularly like the second image in your re-post.

Leonard
That is one of my favorites as well. It's also a 100% crop from this image:

Image
I go by "Jim" in real life, "RoxnDox" on here...

leonardturner
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Joined: Thu Mar 14, 2013 11:40 am
Location: Atlanta, GA, USA

Re: Volcanic Glass

Post by leonardturner »

JIm, regarding your most recent post, I don't think it is a matter of pushing focus stacking too far. This is a rather 3 dimensional subject and may require more images to show sharpness throughout. Make sure that the part of the subject that is closest to the lens is in sharp focus at the beginning and that the last image in your sequence is sharp on the most distant important part. Not everything has to be sharp, but generally the parts in the foreground are most important. If you are doing in-camera stacking, you might want to try obtaining a group by carefully hand focusing and stacking the images with software like Zerene.

Leonard

RoxnDox
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Joined: Tue Mar 31, 2020 4:17 pm
Location: Somewhere near Seattle

Re: Volcanic Glass

Post by RoxnDox »

Thanks, Leonard. My camera doesn't have the ability to stack frames internally, it's just an entry-level model. I have been shooting manual focus in the sequence you described, starting at the nearest and working toward the furthest. I'm using the manual focus rack to adjust each frame's focus thru the optical viewfinder. Camera has a live-view mode, but the screen's low resolution makes it harder to use than the optical... I think I will have to keep working on my ability to find the right place(s) to focus, given these <censored> old eyes of mine. Once I have a sequence, I offload the files from the camera card to my Mac, and combine them in the Focus Stacker (https://www.focusstacker.com) freeware app. Most of the time it gives me pretty good output - nothing I can't blame on myself ;)
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I go by "Jim" in real life, "RoxnDox" on here...

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