An imperfect crystal

leonardturner · Post by **leonardturner** » Tue Jan 30, 2018 2:47 pm

Copper sulfate air dried; Labophot; 20X; halogen lit

Smokedaddy · Post by **Smokedaddy** » Tue Jan 30, 2018 4:50 pm

Very nice.

leonardturner · Post by **leonardturner** » Wed Jan 31, 2018 3:41 pm

Thanks, Smokedaddy, much appreciated. The single crystal was shot as a stack of some 30 images, cross polarized and phase contrast. I've only just started playing with this approach, and am trying it with a variety of chemicals.
Seems to produce a degree of 3-dimensionality.

Mike · Post by **Mike** » Thu Feb 01, 2018 4:14 am

Hello,

Guess the only thing I might argue is why title it 'Imperfect'? Looks great to me!

Being especially interested in crystals under pol illumination, and having done some CuSO4 solutions allowed to dry with less than great, (let alone 'imperfect'!) results, I would be interested in hearing a bit more about your method, if you would not mind.

All the best,
Mike

Jacek · Post by **Jacek** » Thu Feb 01, 2018 1:34 pm

Very nice

leonardturner · Post by **leonardturner** » Thu Feb 01, 2018 3:52 pm

Thanks very much Mike and Jacek; I very much appreciate your kind comments.

Mike, in regards to your inquiry, there are many variables as I'm sure you in particular are quite aware. They would include the concentration of the solution, the rapidity of drying (as would be affected by heat or the addition of volatile agents), and the thickness of the solution. My approach on this crystal was a dilute aqueous solution spread onto a just-cleaned slide and allowed to dry overnight. Try both thick areas, as an individual droplet, and thinned areas with the solution spread over a larger area. My best result was with the thinned areas.

The scope is a regular Labophot with the addition of a small (about 25mm) polarizer at the base of the trinocular head. A second larger polarizer (found in a used camera store bin) is sitting atop the scopes light supply, just below the Nikon Phase Contrast-2 condenser (found on Ebay). The lower polarizer is rotated to extinction and is used without any partial wave modifier. The lens used is a Plan achro 20X Ph2 Nikon. I do my (underexposed) exposures in raw with a Nikon 810. After downloading, the exposure is adjusted and the background is reduced to an absolute black as needed. The stack is made from converted tiff files The final image is cleaned up in Photoshop.

Please note, I claim no expertise here, and just limited experience, but hey, you asked. I'd be delighted to hear the comments of any others who have been down this road.

Best,

Leonard

Mike · Post by **Mike** » Fri Feb 02, 2018 10:23 am

Hello Leonard,

Thanks for the detailed info on your methods as well as the additional shots - really striking with the absolute inky black background really making the crystals 'pop' IMHO!

Is there much benefit in saving the shots as RAW images vs. PNG or some other? Only reason I ask is I am currently laboring with an older laptop setup for the photomicrography work with USB 2.0 ports, so data transfer is a bit slow.

At any rate, thanks again for all the info.

All the best,
Mike

mawyatt · Post by **mawyatt** » Fri Feb 02, 2018 10:31 am

Leonard,

These are beautiful images, love the colors, texture and glass-like appearance!!

Best

Lou Jost · Post by **Lou Jost** » Fri Feb 02, 2018 10:34 am

I'm curious how you manage absolute extinction. With the consumer polarizing films available to me, which I put in front of the lights, I always get some deep indigo highlights. I do like to have some highlights sometimes, so I uncross them a bit to get faint white highlights, but sometimes I would like to completely eliminate them. Any tips on choices of polarizing material?

leonardturner · Post by **leonardturner** » Fri Feb 02, 2018 2:22 pm

My sincere thanks to all of you for your kind comments and questions.

Shooting in RAW is something I began doing with macro/micro photography after reading a post by Charles Krebs a while back regarding protection of highlights. RAW is the only format that carries forward all the information that the camera sensor records instead of using an algorithm to interpret the information into a smaller package. Highlights can be protected through underexposure, and the image can be adjusted by the photographer using the "full deck of cards" before being compressed into a tiff or jpeg file for stacking. I use Photoshop's Image Processor for that transition. Yes, its a bit of a pain and time consuming.

Nothing special about the polarizers; one is a Cokin, the other, I'm not sure. Maybe a Tiffen, but both consumer-grade stuff.

Lou, when I say "adjust to extinction" I mean visually. The background looks black, although it isn't all the way there. That's adjusted after the fact, along with getting rid of unwanted elements in the background. I'm sure there are some losses in the subtleties of the darker tones from this process, but I've liked it for this purpose.

Chris S. · Post by **Chris S.** » Fri Feb 02, 2018 11:04 pm

Lou Jost wrote:I'm curious how you manage absolute extinction. With the consumer polarizing films available to me, which I put in front of the lights, I always get some deep indigo highlights. I do like to have some highlights sometimes, so I uncross them a bit to get faint white highlights, but sometimes I would like to completely eliminate them. Any tips on choices of polarizing material?

Lou, you might check out Edmunds Optics Techspec "Visible Polarizing Laminated Film".

--Chris S.