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Brightfield vs Darkfield

 
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NikonUser



Joined: 04 Sep 2008
Posts: 2577
Location: southern New Brunswick, Canada

PostPosted: Tue Feb 10, 2009 3:40 pm    Post subject: Brightfield vs Darkfield Reply with quote

My first attempt at Darkfield Illumination; slide mounted Cat Flea
Using the Swift microscope and suggestions on page 5:
SEE HERE
Top image: brightfield illumination using microscope's built-in substage tungsten lamp.
Bottom: Darkfield illumination; simply placed a black disc in the center of the substage condenser.
4x objective, 180mm bellows + extension ring, 13 frames @ 0.015mm HF stack for top image; 5 frames @0.03mm HF stack for bottom image. Mirror lock up.

1st lesson learned: make sure everything is dust free; the few dust spots seen in brightfield magically turn into dozens (hundreds?) in darkfield; clean up before photographing.



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Nikon camera, lenses and objectives
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Mike



Joined: 04 Aug 2006
Posts: 86
Location: Northeast Ohio

PostPosted: Tue Feb 10, 2009 6:03 pm    Post subject: Reply with quote

Hello,

Actually I think both shots are quite good - that's not dust on the DF image, compare the locations of the spots with the BF image.

What camera, exposure, etc did you use?

Best,
Mike
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Charles Krebs



Joined: 01 Aug 2006
Posts: 5805
Location: Issaquah, WA USA

PostPosted: Tue Feb 10, 2009 8:16 pm    Post subject: Reply with quote


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NikonUser



Joined: 04 Sep 2008
Posts: 2577
Location: southern New Brunswick, Canada

PostPosted: Wed Feb 11, 2009 2:43 pm    Post subject: Reply with quote

Mike wrote:
What camera, exposure, etc did you use?
Mike

Mike: I used a Nikon D2Xs set for Shutter Priority and Tungsten WB. Illumination was from the built-in substage tungsten lamp on the microscope. The camera will record a NEF image and a fine JPG with a single shutter release. These shots are stacks from the JPG's. The BF was 1/250 sec, ISO 100; the DF was 1/8 sec also ISO 100. Mirror lock-up for all frames.

The 4x objective is designed for 160mm tube length. Unfortunately the wide base on the D2Xs prevents it being attached directly to the PB-6 bellows. I have to use an extension tube, in this case a 52.5mm PN11, to connect the camera to the bellows. Even with the bellows at no extension the actual distance between sensor and bottom of objective is 180mm. Images may have been better if I had used a 160mm tube length.
_________________
NU.
student of entomology
Quote – Holmes on ‘Entomology’
” I suppose you are an entomologist ? “
” Not quite so ambitious as that, sir. I should like to put my eyes on the individual entitled to that name.
No man can be truly called an entomologist,
sir; the subject is too vast for any single human intelligence to grasp.”
Oliver Wendell Holmes, Sr
The Poet at the Breakfast Table.

Nikon camera, lenses and objectives
Olympus microscope and objectives
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View user's profile Send private message
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