Calcite crystal cave in a Madagascan ammonite

Bruce Williams · Post by **Bruce Williams** » Tue Jan 02, 2007 5:51 pm

Hi folks,

The ammonite is from Madagascar (I'm afraid I don't have the specific name), however according to the supplier it is from the Late Jurassic . The photos are not particularly informative - but I do think they're quite pretty.

The lighting was positioned differently for the two photos.

The second photo (stackX9) shows a chamber where the calcite crystals growth has failed to completely fill the available space. In my experience this is quite rare. The crystal opening is approximately 1.5 mm measured across the longest point. In both photos the misty areas actually are indistinct and smokey in reality and hint at underlying structures (mainly the folded septa) seen through the variously tinted calcite. As a separate exercise, I did try focusing down through the calcite but the results were disappointing (even to the eye).

Bruce

svalley · Post by **svalley** » Tue Jan 02, 2007 6:06 pm

Bruce, nice shots of an interesting subject.

What sort of stacking system are you using?

Bruce Williams · Post by **Bruce Williams** » Tue Jan 02, 2007 6:30 pm

Thanks for your comments Steve.

I'm using CombineZ5 (v5.3). It's public domain software and seems to work quite well on this sort of subject. Todate I have found that the default function set has produced acceptable results in almost every case. Very occasionally I have had to use Photoshop to clone out the odd intrusive artifact.

I manually judge the z-stepping process (well I have no choice

) on my Meiji EMZ-5TR stereo and then quickly examine the results in Windows Explorer before deciding on the set to be stacked.

Bruce

beetleman · Post by **beetleman** » Wed Jan 03, 2007 12:24 pm

Great job on these wonderful creatures Bruce. The small crystal chamber came out excellent with the stack. A while back I posted an ammonite that was replaced with Iron Pyrite. http://www.photomacrography.net/forum/v ... t=ammonite

Bruce Williams · Post by **Bruce Williams** » Wed Jan 03, 2007 12:50 pm

Thanks Doug.

I just took a look at your ammonite photos - an amazing piece and not an easy subject to photograph I would imagine. I have come across the odd microscopic "nugget" of pyrite but have never seen anything quite like your Russian ammonite.

Bruce

rjlittlefield · Post by **rjlittlefield** » Wed Jan 03, 2007 1:29 pm

Bruce Williams wrote:I'm using CombineZ5 (v5.3). It's public domain software and seems to work quite well on this sort of subject.

One small nit -- "public domain" is not quite correct. Copyright is retained by Alan Hadley, the author. He allows other people to use, modify, and redistribute the binaries and source code, at no cost, but only under terms of the GNU Public License (GPL). If someone wanted to use the software under other terms, they would have to cut a separate deal with Alan. This contrasts with "public domain" software, which anyone can use however they like, without restriction.

The distinction does not make any difference to most users of the software, but it's really important from the standpoint of code developers.

--Rik

Bruce Williams · Post by **Bruce Williams** » Wed Jan 03, 2007 1:41 pm

Hi Rik,

This from within CombineZ5 (Help/About):

Presumably Alan Hadley's own words (but quite possibly not "technically" correct

)

Bruce

.

rjlittlefield · Post by **rjlittlefield** » Wed Jan 03, 2007 2:51 pm

Well, that's amusing!

Alan and I talked a lot about how the GPL works, when I suggested that he release source code under it in the first place. And I reviewed all the early CombineZ5 documentation. But this particular paragraph is surely one that I never laid eyes on. Perhaps a recent addition -- don't know, doesn't really matter.

At least the GPL statement sits right next to the "Public Domain" words, so Alan's copyrights are still protected.

Thanks for letting me know,
--Rik