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Circular Oblique Lighting

 
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Smokedaddy



Joined: 07 Oct 2006
Posts: 797
Location: Phoenix, Arizona

PostPosted: Sun Feb 26, 2017 9:42 pm    Post subject: Circular Oblique Lighting Reply with quote

I've been trying to find a non-technical step by step procedure for setting up Circular Oblique Lighting with my Optiphot and a Phase Condenser. I have searched the Internet as well as here without success. Does anyone have a link or care explain from a beginners perspective?

Regards,
-JW:
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Beatsy



Joined: 05 Jul 2013
Posts: 911
Location: Malvern, UK

PostPosted: Mon Feb 27, 2017 1:02 am    Post subject: Reply with quote

Micscape has quite a lot of relevant articles, did you look at those. Just google 'col micscape' without the quotes. This is a pretty comprehensive example...

http://www.microscopy-uk.org.uk/mag/artnov10/tc-col.html
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Smokedaddy



Joined: 07 Oct 2006
Posts: 797
Location: Phoenix, Arizona

PostPosted: Mon Feb 27, 2017 10:59 am    Post subject: Reply with quote

Thanks Steve, I've found a few references but they're too wordy for my needs. I was just looking for a simple step-by-step visual procedure not a thesis. That particular article and others I've found are useful but not for a beginner simply wanting to setup their scope for COL. Appears I'm looking for COL procedure for dummies.
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gpmatthews



Joined: 03 Aug 2006
Posts: 1015
Location: Horsham, W. Sussex, UK

PostPosted: Mon Feb 27, 2017 12:06 pm    Post subject: Reply with quote

If you know how to achieve darkground with a wheel or patch stop, then you know how to do COL: just use an undersize stop in the condenser filter holder. You may need to rack the condenser up or down bit from the normally optimum position to achieve satisfactory results.
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Graham

Though we lean upon the same balustrade, the colours of the mountain are different.
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Ichthyophthirius



Joined: 07 Mar 2013
Posts: 728

PostPosted: Mon Feb 27, 2017 3:07 pm    Post subject: Reply with quote

Hi,

Do you have a phase contrast condenser already? All it involves is:

- use bright-field objectives
- use the objective with an annulus intended for an objective with higher magnification (e.g. the objective 40:1 with the annulus for the 100:1)

See here: http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/artdec02/pjcol.html

However, the "ideal" annulus size depends very much on the object. No annulus diameter fits all objects equelly well.

At this point, people will start making their own annuli and insert them into the condensers until they have a set of different sizes that suit their needs.

The Optiphot PH/DIC condenser I have can't be opened by the user so the annuli can't be exchanged. This makes it harder to implement in this system.

Condensers with variable annulus diameters give you more scope to play around with COL and near-darkfield. Especially the Leitz Heine condenser (expensive!) and the Zeiss Jena pankratic Phv condenser. But they are no quick fix for your Optiphot.

The simple Abbe condenser NA 1.25 http://www.prc68.com/I/Labophot.html for the Labophot http://www.prc68.com/I/Images/NkPhTel04b.jpg appears to have a slot for phase annulus sliders: http://www.prc68.com/I/Images/Labophot06b.jpg If you get one of those, you can make your own set of annulus sliders in the style of these Ebay products: http://www.ebay.co.uk/usr/daedal2005

This condenser might not be very common.

Regards, Ichty
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Smokedaddy



Joined: 07 Oct 2006
Posts: 797
Location: Phoenix, Arizona

PostPosted: Mon Feb 27, 2017 5:18 pm    Post subject: Reply with quote

Ichty, thanks for trying to explain. Just to be clear I'm talking about a Optiphot only and yes I have a Nikon 1.25 phase contrast condenser. I only have a few objectives, Meiji Phase DM 40x/0.65 DIN, SMPlan4x/0.1-160/0.17, Phase DM 100x/1.25 DIN, Phase DM 10x/0.25 DIN and Plan2.5x/0.08 DIN, a Nikon 10X/0.25 DL, Ph1, Nikon Plan 40x/0.65 Ph 3 and a Nikon Plan 60x 0.85 160 0.11-0.23.
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GaryB



Joined: 29 Jul 2016
Posts: 373

PostPosted: Tue Mar 07, 2017 1:40 am    Post subject: Reply with quote

If you have a printer, you can download the images of the COL filter sets on ebay and print them out on clear printer sheet. You may need to scale them up a little before printing but it'll give you a starting point of what sort of size COL rings you need for each objective.

It could save a few headaches in testing.
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