Polarized light photography under$700?

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jswift
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Polarized light photography under$700?

Post by jswift »

A complete novice to microscopy, I've been trying to find equipment for photos of crystals and other things in polarized light. I have a Sony Nex-7 camera.

Is it possible to do this with a budget of under $700?

If so please could you point me in the right direction for further research, maybe in the direction of adapting a microscope for polarized light.

Also does anyone know of a retail source for microscopes in Victoria, BC?

Many thanks

Jim Swift
Vancouver Island, BC

NikonUser
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Post by NikonUser »

This probably doesn't answer your question but Olympus made a polarizing attachment for their BH2 microscopes BH2-KP. It consists of 4 components and works very well. Several of my images with it on this site.
Used on e-bay for about $300-400.
I suspect that different microscopes have their own, similar, attachments.
NU.
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Nikon camera, lenses and objectives
Olympus microscope and objectives

chrismower
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Post by chrismower »

I have just been tinkering with this myself and was wondering if my experiments might be of interest to anyone else.

I recently purchased a Leitz Orthoplan and the seller kindly threw in a polarising filter and showed me what could be achieved when the analyzer was inserted into the light path. It was quite astonishing and I resolved to get my hands on one, but after scouring eBay they just don't seem to be available.

After reading up on the subject I figured out that I could build one quite easily and so after a bit of thought I took a pair of scissors to some cardboard and a set of cheap 3D glasses (not the red/green ones but the ones that look like dark glasses) from the cinema and within an hour I had an analyser that was completely functional. I later made a more durable version using tough plastic rather than cardboard.

If you get the lenses out of the 3D glasses and place one behind the other and look through them as you rotate one you will find that as you rotate they will suddenly darken. If not you need to flip one of them over. If they still don't darken then you have probably got the wrong type of glasses.

To use you need to place one lens between the light source and the object being examined and the other between the object and the eye/camera. This can be before the lens on the microscope or after it.

The downside is that you need to have a very bright light source since as you approach maximum cross-polarisation the light levels drop dramatically.


If anyone is interested I will post pictures but it is all pretty straightforward. I suspect that someone else has done this previously but as I am new to the board I haven't had time to check yet.
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DaveBH
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Post by DaveBH »

Chris, whenever you have time I'd definitely be interested in seeing some pics and reading more about your polariser/analyser.

cheers
DaveBH

Pau
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Post by Pau »

DaveBH wrote:Polarized light photography under$700
Of course you can do it!

Almost any pair of polarising filtres may do the job and provide very interesting observation of birrefringent specimens (most crystals but also polymers that have some spatial predominant orientation like cell walls, protein filaments...)

But not all will deliver the same quality (nor cost the same price!). For photomicrography you want good quality ones that provide high extintion and no color cast when crossed, and at the camera side you want one of good optical quality. Photographic filters usually produce strong color casts when crossed, but few ones don't. Its extintion rate also often is not great (although if you have them may be worth to test, and even in the worst case still can produce nice effects)
Microscope pol filters are usually of the best quality because are designed just for this application, but usually expensive even used (although often within you budget).

An excellent alternative are the Techspec polarizers from Edmund Optics. You can use the Techspec film as polarizer and a Techspec glass filter as analyzer (I use one of these in my DIC microscope and is practically as good as a Nikon analyzer I tested against it), or two glass ones.

In most microscopes, if you don't have the dedicated slot to put the analizer you can just drop it inside the microscope head over the objective. Don't place the analyzer between the microscope objective and the sample, but between the objective and the eyepiece and/or camera.
For the polarizer a good place is over the illumination source.
You need the ability to rotate at least one of the filters. With adapted microscopes usually is much easier to rotate the polarizer.

A rotating stage is very nice to have because light polarization is very direccion sensitive, but you can live without it at least at the beginning.
Pau

Olympusman
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Polarizing microscopes

Post by Olympusman »

I wrote an article on hybrid polarizing setups a few years ago for Micscape. It can be found at http://www.microscopy-uk.org.uk/mag/ind ... polar.html
Michael Reese Much FRMS EMS Bethlehem, Pennsylvania, USA

DaveBH
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Post by DaveBH »

"Polarized light photography under $700"

Not my quote, Pau - I'd have asked, "Polarized light photography for under $40?" !!

Lots of things are 'possible' if you don't need a Ferrari 8>)

There is so much old lab equipment sitting around in junk piles. Where are the DIY threads? I can make a revolving stage in a few hours, a pocket for a filter in 20 minutes. I have many photo polarising filters. Problem is I have little or no micro/optical theory, only what I read here and there 8>)
(Unfortunately I can't make a $1800 objective lens 8>/

(PS Michael, thanks for the link. I will try this.)

cheers
DaveBH
Last edited by DaveBH on Thu Jan 31, 2013 12:50 pm, edited 1 time in total.

Charles Krebs
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Post by Charles Krebs »

Jim,

Very "doable" with your budget".

If you are looking at microscopes and already know that cross-polarized lighting is a primary interest then it makes sense to keep an eye out for one that allows insertion of a polarizer ("analyzer") somewhere above the objective but before the eyepieces. This is not absolutely essential but it does make cross-polarization easier. Such microscopes are far less common than those without such a provision, but it doesn't hurt to keep it in mind when looking.

I will also strongly recommend Edmund Optics Techspec polarizing film:
http://www.edmundoptics.com/optics/pola ... -film/3435
The color neutrality and extinction ratio are excellent. It seems to provide results as good as my Olympus microscope polarizers. I use it over the base light "port", but not in the image path. In the optical path I stay with an Olympus microscope polarizer. (But I have been meaning to "test" a piece of this material in the optical path. At 0.18mmIt it is pretty thin so it might do better optically than expected. Since it can be easily cut to size, it would often be far easier to implement than a "glass" filter. If I ever do this test I'll add the results to this thread).

DaveBH
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Post by DaveBH »

I'm confused about something (as usual). I've noticed in at least one diagram of a polarising microscope in a manufacturer's brochure that (among other complications) the analyzer is shown angled (i.e. non-perpendicular) in relation to the optical axis.

Or, can it be as simple as fitting a common circular polariser (i.e. one that includes a 1/4-wave plate) over the light source, and a linear polariser between the objective and the eyepiece(s)?

As they might say in the cheap internet ads, 'manufacturers don't want you to know about this!' 8>)

DaveBH

Pau
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Post by Pau »

DaveBH wrote:"Polarized light photography under $700"

Not my quote, Pau - I'd have asked, "Polarized light photography for under $40?" !!
Sorry Dave, it was the original title, not yours of course :D

Of course this may also be done under $40, but not easily for high quality filters. But top quality materials are not always needed, and as I said you can get nice results with almost any polarizer. At work I have converted few biological Olympus CH clones to petrographic ones with cheap plastic polarizers and an added rotating stage and they are full valid for teaching ellementary Petrology (but I much prefer the higher quality optics and filters I have at home)

I have seen angled filters in infinite Nikon microscopes. I have a Nikon analizer that it a bit angled in its mount. This must be intended to avoid reflections, but usually this isn't problematic.

Camera pol filters may be useful but usually not the best ones as them aren't designed to work crossed like microscope ones and often induce color casts (usually blue) when crossed.

And yes, this is that simple.
Last edited by Pau on Fri Feb 01, 2013 4:56 pm, edited 1 time in total.
Pau

DaveBH
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Post by DaveBH »

No problem, Pau 8>) I always enjoy your very informative posts

I looked, and yes, all my PL filters ('linear'?) turn deep blue at their peak position - bummer! 8>/ And the glass (two cemented together?) is very thick, so altogether not good as an 'analyzer' (still don't understand that term!) in a microscope.

So, I see the Edmunds linear polarising material is $40 for 4" (100mm) square piece - what a coincidence 8>) It is thin, so a piece would easily slip into the dovetail pocket under my trinocular head.

I am not there yet, though...

cheers
DaveBH

Charles Krebs
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Post by Charles Krebs »

I just tried a piece of the Edmund Techspec polarizing film in the image path and I would advise against it. It can be used under the specimen with no problems at all, and as mentioned earlier it is very neutral and has very high extinction.

But when placed in the image path (above the objective) and compared to an Olympus polarizer the image resolution is clearly not as good (at least in my microscope with the piece I used).

DaveBH
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Post by DaveBH »

(post deleted)
Last edited by DaveBH on Fri Feb 01, 2013 9:19 am, edited 1 time in total.

chrismower
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Post by chrismower »

OK, here are some pictures that I took of the set-up I used. I have a Leitz POL filter and a Leitz analyser which I have just purchased, but the simple set-up below worked fine for a few months before I got the real thing.

The picture quality is actually not bad. I tried about a dozen different 3D glasses until I found one that had very good clean flat thin plastic lenses. The polariser filters were from my camera bits and pieces box.

Compared to the official Leitz equipment the results are not all that dissimilar. This could be due to the fact that the Leitz polariser and analyser are at least 25 years old and probably older.

The picture shows it being used in the OrthoPlan but I also managed to get it working in the SM-Lux which doesn't have an Analyser slot. What I did was remove the binocular head and placed a small piece of the polariser film in the bottom of the hole just over the aperture to the objective lenses. A bit fiddly but it worked.

While a agree with the comments by other users that this may not be as good as a shop-bought one, it is cheap and easy and the results I managed to get were far better than I expected. By rotating the Polariser filter over the light source I could get almost total extinction.

By removing the analyser and just rotating the polariser filter I was able to get some fascinating light shows from various crystals.

The beauty of it is it only cost a couple of pounds to get started. Cheap and Cheerful I think the expression is ....... :-D

Image

Image[/img] :D :D :D

DaveBH
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Post by DaveBH »

Charlie, what are we looking for, as far as a pol filter that's more/less likely to work as an analyzer?
I dismantled one of my polarising filters, marked 'PL' (not 'CPL'), an old 30.5mm Hoya. I would think it's a decent piece of glass?
The glass itself is 28mm dia. and about 2mm thick. It should easily fit in there just above the nosepiece, so I might give it a shot.

DaveBH

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