[meteorite-list] First attempt at photographing thin sections

From: Richard Kowalski <damoclid_at_meteoritecentral.com>
Date: Tue, 5 Oct 2010 11:31:45 -0700 (PDT)
Message-ID: <70583.18094.qm_at_web113601.mail.gq1.yahoo.com>

--- On Tue, 10/5/10, Starsinthedirt at aol.com <Starsinthedirt at aol.com> wrote:

<snip>


> My tip. Now that you have seen what can be
> done, loose the plastic
> polarizing film. Buy cheap glass camera polarizes
> or sacrifice a couple you
> already have lying around. Cut them to size
> with your rock saw (Any diamond
> blade, water cooled tile saw will do). You will
> enjoy your time spent much
> more.
>
> Tom



and --- On Tue, 10/5/10, David Pensenstadler <dfpens01 at yahoo.com> wrote:

>
> I understand that one should only use linear polarizers and
> that most camera polarizers are circular. So, be
> careful with what you use.
>
> Perhaps Tom Phillips can shed some light on the differences
> in polarizers.
>
> Dave



Thanks to all of you who commented publicly and privately.

I'll add a couple of comments to what I did as it was a bit unconventional but easily reproducible to others who have a biologic microscope at hand instead of a "proper" geologic or petrologic microscope at hand.

I'll start off with the polarizer. Thans for the suggestion Tim. I'll have to look at obtaining some of this material. The polarizing sheet I have is a higher end linear polarizing sheet that I obtained for another photography project. I cut a piece that was larger than the aperture of my condenser and simply rest that on top of the condenser housing. This is the polarizer I am rotating to provide the cross polarization. The second polarizer is a small circle of the material that is placed inside the microscope, in an open area below the viewing head. This might have some purists shaking their heads, but it lets me use the instrument I have and as you can see, at this basic level it works.

The trinocular microscope allows one to mount the camera, in my case a Canon 50D, directly on the microscope while leaving the binocular eyepieces available for watching the changing polarization and to find the most interesting patterns & colors and to easily find the more interesting or appealing areas on the specimen. The 50D has "live view" so I can make any final adjustments to position and focus on my computer screen before making the image.


A few people have commented privately about the lack of focus around the edges. Unfortunately this is due to the nature of the objectives on my microscope.

I plan on upgrading my objectives to what is known as "plan objectives" which provide better correction and flat fields as time & budget allow, so this should be less of an issue for my photography in the future.

For those of you who have microscopes of any design, I'd suggest you give this a try. It's certainly an interesting exercise and even if you don't make any images, watching the changing patterns and colors of the samples is fascinating.

Thanks again for your kind words and suggestions.

Richard




      
Received on Tue 05 Oct 2010 02:31:45 PM PDT