Joined: Thu Dec 13, 2007 4:16 pm Posts: 219 Location: Georgia USA
I've been waiting for a long time to take some photos with the Wild M420 Apozoom that I bought last summer, and finally received the Diagnostic Instruments camera coupler that I had ordered to couple with my Olympus E-510 DSLR. The couplers had undergone a complete redesign, so it took a while for them in process the order. It's well made and worth the wait. In the meantime, Gene (G4Lab) set me up with a fiber darkfield unit and provided answers to a lot of my newbie questions.
Here’s the first attempt – a Taita-Taveta color-change garnet from Kenya, which I saved to photograph because I liked the rutile. It's is really not that visible in normal lighting but really pops under the darkfield. I also used the free trial version of the Zerene Stacker software for the first time, and found it extremely easy to use. 104 individual photos were used for this photo stack. Now I need to rummage through all my other stones looking for more cool stuff!
Gary
_________________ Gary Braun www.finewatergems.com
Last edited by Finewater Gems on Thu Apr 07, 2011 5:29 pm, edited 2 times in total.
Post subject: Re: First attempt at photomicrography
Posted: Fri Apr 08, 2011 11:51 am
Gold Member
Joined: Wed Nov 15, 2006 9:44 pm Posts: 1079 Location: Washington State
Finewater Gems wrote:
104 individual photos were used for this photo stack
That's a really neat shot, but I don't understand this comment. I'm assuming that a "photo stack" is a combination of 104 independent exposures? What is the benefit of using so many? I've never looked at this process and am just wondering why so many. Thanks for an explanation!
Post subject: Re: First attempt at photomicrography
Posted: Fri Apr 08, 2011 12:13 pm
Valued Contributor
Joined: Thu Dec 13, 2007 4:16 pm Posts: 219 Location: Georgia USA
Hi Michael. The depth of field at these magnifications is very small. A single photograph would have only a single "slice" of the gemstone in focus, and everything else would remain out of focus. In this case I started near the top of the stone, took a photo, moved the focus slightly a little more "into" the stone, then another photo, and stepped all the way through until the last area of interest was in focus. All the photos are then imported in the stacking software, where it aligns the photos and selects the in-focus bits from each shot, then assembles them into a single photo. 104 photos was probably overkill so I'll have to experiment with varying step sizes.
Gary
_________________ Gary Braun www.finewatergems.com
Post subject: Re: First attempt at photomicrography
Posted: Fri Apr 08, 2011 2:24 pm
Valued Contributor
Joined: Thu Dec 13, 2007 4:16 pm Posts: 219 Location: Georgia USA
Thanks Michael, but it’s actually not that bad – about 20 seconds per shot. Enough time to re-focus, wait a few seconds for any vibrations to die down, press the remote shutter release, wait for the camera to raise and lock the mirror for a few seconds, take the shot, and then it’s time to start again and refocus. Some of the guys over on the photomacrography.net forum have really elaborate setups with automatic stepper motors and shutter releases, but it’s not really that difficult to do it manually. Here’s one that I just finished in about 30 minutes elapsed time – a different color-change garnet that had a cool veil of small inclusions along with some rutile.
_________________ Gary Braun www.finewatergems.com
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