Nikon 2.5x CF M Plan Achromat

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NikonUser
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Location: southern New Brunswick, Canada

Nikon 2.5x CF M Plan Achromat

Post by NikonUser »

NA 0.075, WD (at 210mm TL) 11 mm
Nikon warns "Will vignette with 10x UW eyepiece

D90. 0n bellows, 200mm extension, 2 flashes, styrofoam cup diffuser, 39 frames @ 0.05mm ZS PMax.

Top: full frame
Middle: 1950px selection (reduced to 500px)
Bottom: 1000px selection of actual pixels.

NB: lens has good resolution; can reduce/eliminate dark corners by increasing extension BUT WD almost disappears.

This is a Pollenia (Cluster fly); lens may be useful for larger roundish objects (horse fly head?)

Image Image

Image
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.

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dmillard
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Joined: Tue Oct 24, 2006 7:37 pm
Location: Austin, Texas

Post by dmillard »

Hello NU,

I'm surprised by the great degree of vignetting that you experienced with this objective, and wonder if some might perhaps result from obstruction due to your mechanical connection. In this image that I took of a relatively flat transilluminated subject, very little vignetting was apparent. I think that I used 210mm extension (rear of objective to sensor plane), but I'll double check this weekend.

Best regards,
David
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NikonUser
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Joined: Thu Sep 04, 2008 2:03 am
Location: southern New Brunswick, Canada

Post by NikonUser »

David:
I cannot connect the D90 directly to the PB-6 bellows, have to use an extension tube.
The above photos were with a 3rd-party short tube. I replaced the tube with a Nikon PN11 and got a similar amount of vignetting I guess it is something I will have to live with.
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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