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Saul
Joined: 31 Jan 2011
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Location: Naperville, IL USA
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Harald
Joined: 13 May 2011
Posts: 423
Location: Steinberg, Norway
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 Posted: Tue Jul 12, 2011 4:12 pm Post subject: |
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Hi,
In order to get polarized light trough a microscope, the filter must be linear polarizer. He says "almost black". To get polarized it must be black.
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Harald
Lier Fotoklubb / NSFF
AFIAP / CPS
BGF / GMV
http://www.500px.com/blender11 |
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Saul
Joined: 31 Jan 2011
Posts: 1060
Location: Naperville, IL USA
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| Posted: Wed Jul 13, 2011 6:49 am Post subject: |
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| I'm using for flash-diffuser cross polarization , it works. |
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bromodomain
Joined: 02 Jan 2011
Posts: 134
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| Posted: Wed Jul 27, 2011 1:21 pm Post subject: |
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I've used the polarizing film from the LCD screen of a tetris game. It did work but its was pretty scratched so the image wasn't perfect. I think its a good price if you cant afford proper polarising filters  |
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Saul
Joined: 31 Jan 2011
Posts: 1060
Location: Naperville, IL USA
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| Posted: Wed Jul 27, 2011 2:11 pm Post subject: |
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it is not for lens. I'm using it inside diffuser around object (milk plastic type cylinder, film is attached to the inner surface), other polarizing filter (Cokin p type polarizer) is sitting on my flash. By rotating it, you can remove extra bright details from your object. Of course, you can use normal polarizing filter on the lens instead on the flash, but in this case you have one more additional glass between your object and sensor and you can loose little bit of sharpness (depending of the quality of your polarizing filter). And it is not comfortable to rotate it, if your stacking setup is complex or vibration sensitive. And there is one more thing - because of that rotating ring, your optical setup will have micro creep - microscope objective is sitting on the polarizing filter - surface of the objective will be not parallel (fully) to the sensor. This does not apply, if you are using vertical setup. Sorry for my English.
BR,
Saul |
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Pau
Site Admin
Joined: 20 Jan 2010
Posts: 4241
Location: Valencia, Spain
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| Posted: Wed Jul 27, 2011 2:46 pm Post subject: |
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| Harald wrote: | Hi,
In order to get polarized light trough a microscope, the filter must be linear polarizer. He says "almost black". To get polarized it must be black. |
Not so much, circular pol filters are linear ones with 1/4wave plate in one side, if the two linear parts of both filters are facing you can get cross polarization (it's easy to test crossing them in front of a white lamp)
In fact some modern high end microscopes use circular pols as analyzers.
100% extintion (pure black) is not always possible, and it isn't necessary in order to get a notable effect. I'm used to work every day with school microscopes equiped with plastic pol filters. For some more exigent applications like quantitaive analysis or DIC only the best filters are suitable.
The worst issue with most (but not all!) photographic pols is that they induce a strong color cast, usualy blue, when crossed
more info and discussions:
http://www.photomacrography.net/forum/viewtopic.php?t=10706&highlight=
and
http://www.photomacrography.net/forum/viewtopic.php?t=10821&highlight=
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johan
Joined: 06 Sep 2011
Posts: 972
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| Posted: Wed Sep 07, 2011 3:53 am Post subject: |
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Very new here, and only learned about this technique a couple of days ago, but I came across this the other day and it arrived on my desk this morning:
Polarising Glass Stress Check Polarizing Film 21x15cm
£13.99 for 21x15 cm flexible film, should be good for a few flash output covers |
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