Eye tube clamp for Nikon Optiphot/Labophot UW head afocal imaging

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blekenbleu
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Eye tube clamp for Nikon Optiphot/Labophot UW head afocal imaging

Post by blekenbleu »

Nikon's default trinocular camera field is smaller than visible in e.g. 10X/23 oculars.
I intend to compare various trinocular hacks, and having repeatable afocal results seemed useful.
Eye tubes on Type UW heads have 36mm o.d., and 30mm oculars do not fit inside M42 extension tubes.
An SVBONY SV148 2-inch telescope clamping extension tube nicely clears 30mm oculars and has a 48mm internal thread.
Image
A 36mm to 2-inch spacer was fabricated from 16mm delrin using hole saws and sandpaper.

The SV148 was shortened to 42mm, then adapted to the camera,
e.g. using 48-49mm and 49-52mm step-up rings for Canon's 40mm lens:
Image

Gruesome DIY details here: https://blekenbleu.github.io/microscope/M48.htm
Metaphot, Optiphot 1, 66; AO 10, 120, and EPIStar 2571
https://blekenbleu.github.io/microscope

iconoclastica
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Location: Wageningen, Gelderland

Re: Eye tube clamp for Nikon Optiphot/Labophot UW head afocal imaging

Post by iconoclastica »

I am using the discussion head. The field of view is identical in the vertical (short) dimension and then wider of cource in the horizontal direction. So what I get is what I see, plus some 50% (not regarding the corners)

This is how they compare:
view.jpg
.
--- felix filicis ---

blekenbleu
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Re: Eye tube clamp for Nikon Optiphot/Labophot UW head afocal imaging

Post by blekenbleu »

iconoclastica wrote:
Tue Oct 04, 2022 1:37 pm
I am using the discussion head.
I see them occasionally on eBay, often incorrectly described as trinocular.
I understand that they apply 1.25 magnification while extending finite objective intermediate image plane for a stacked head.
The field of view is identical in the vertical (short) dimension and then wider of cource in the horizontal direction. So what I get is what I see, plus some 50% (not regarding the corners)
If I understand correctly, field of view out the vertical port would be reduced because of 1.25x magnification,
compared with oculars which I suppose get unmagnified view from beam splitter.
[/quote]
.. so the T1 camera here https://www.photomacrography.net/forum/ ... 867#240867
captures highly vignetted circular images, compared with typical trinocular with photo relay lens
or intermediate image capture using e.g. Nikon's trinocular F head with a short 38mm tube and mirrorless APS-C camera, e.g.:
https://www.photomacrography.net/forum/ ... 28#p283228
... which crop a rectangle within Nikon's circular field.
Images that you obtain could be approximated using with the trinocular F head, short tube and mirrorless 35mm sensor instead of APS-C ,
or a so-called speed booster (opposite of 1.4x telextender) with APS-C.

Using 210mm tube length Nikon CF objectives with a vertical illuminator, then
adding a discussion head (seemingly intended for 160mm objectives) on that would, I imagine, provoke aberrations.
Metaphot, Optiphot 1, 66; AO 10, 120, and EPIStar 2571
https://blekenbleu.github.io/microscope

Scarodactyl
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Re: Eye tube clamp for Nikon Optiphot/Labophot UW head afocal imaging

Post by Scarodactyl »

blekenbleu wrote: Using 210mm tube length Nikon CF objectives with a vertical illuminator, then
adding a discussion head (seemingly intended for 160mm objectives) on that would, I imagine, provoke aberrations.
210mm objectives use the same heads as 160mm objectives. They just have to have the appropriate illuminator below them.

blekenbleu
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Re: Eye tube clamp for Nikon Optiphot/Labophot UW head afocal imaging

Post by blekenbleu »

Scarodactyl wrote:
Tue Oct 04, 2022 4:07 pm
210mm objectives use the same heads as 160mm objectives. They just have to have the appropriate illuminator below them.
I understand that; my confusion is whether lenses in inserts (e.g. for polarizing or discussion heads)
for extending 160mm objective intermediate focal planes also work correctly for 210mm objectives.
Metaphot, Optiphot 1, 66; AO 10, 120, and EPIStar 2571
https://blekenbleu.github.io/microscope

iconoclastica
Posts: 486
Joined: Sat Jun 25, 2016 12:34 pm
Location: Wageningen, Gelderland

Re: Eye tube clamp for Nikon Optiphot/Labophot UW head afocal imaging

Post by iconoclastica »

Hmm, you make it sound complex. Not sure if I folow it all.
blekenbleu wrote:
Tue Oct 04, 2022 4:03 pm
.. so the T1 camera here https://www.photomacrography.net/forum/ ... 867#240867
captures highly vignetted circular images,
Nope. Only the utmost corners are vignetted. As you can see in the photo above which was taken with exactly this setup. Only the field aperture is clearly visible of course when adjusted properly to the oculars.

There is a 1.25x magnification in the head. It works both on the oculars and the 3rd eye. I reckon it magnifies the primary image from 23+mm to 28+mm so it covers the diagonal of APS-C. This setup works for APS-C and smaller sensors. FF will be vignetted.

Since a normal binocular head can be stacked on top, the projection of the 3rd eye must be relayed some 60mm upward.
--- felix filicis ---

iconoclastica
Posts: 486
Joined: Sat Jun 25, 2016 12:34 pm
Location: Wageningen, Gelderland

Re: Eye tube clamp for Nikon Optiphot/Labophot UW head afocal imaging

Post by iconoclastica »

Scarodactyl wrote:
Tue Oct 04, 2022 4:07 pm
blekenbleu wrote: Using 210mm tube length Nikon CF objectives with a vertical illuminator, then
adding a discussion head (seemingly intended for 160mm objectives) on that would, I imagine, provoke aberrations.
210mm objectives use the same heads as 160mm objectives. They just have to have the appropriate illuminator below them.
Thats correct. The optical path in the epi-illuminator only contains a half mirror so it is lengthened by 50mm. The UV-illuminator also translated the primary image so the apperent path length still is 160mm.
--- felix filicis ---

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