"Hybrid" 160mm TL Zeiss KPL eyepiece projection photography

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Hobbyst46
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Joined: Mon Aug 21, 2017 9:02 pm

"Hybrid" 160mm TL Zeiss KPL eyepiece projection photography

#1 Post by Hobbyst46 » Sun Apr 11, 2021 7:06 pm

Very recent experiments on "hybrid" Zeiss eyepiece projection photography with my 160 TL Zeiss microscope. I was motivated by the work of Rolf Vossen ("Microphotography with ‘hybrid’ eyepieces", https://microscopyofnature.com/experiments-and-tests), and exchange of ideas with Bob (MicroBob). My projecting eyepiece is actually "half-hybrid": the eye lens from a 10x KPL eyepiece, the barrel and field lens from a 8x KPL (both LOW eyepoint eyepieces). The eyepiece is fitted as usual into the trino phototube, not "lifted". It is not parfocal with the bino eyepieces. The camera body is connected on top of the phototube via a cheap M49-1.25" telescope adapter and various extension rings. The APS-C sensor is roughly 9.5cm higher than the projecting eyepiece. The camera at this height is made exactly parfocal with the viewing eyepieces, and parfocality is maintained for all objectives. Chromatic aberration is weaker than in my previous afocal setups; pincushion is very slightly worse, but still acceptable for me, and FOV coverage is ~70%. For example, here is the image of the stage micrometer, taken with a 25x0.45 Plan achromat. Post processing included color profile (shown in a separate graph) and grey background removal.
non-raised half-hybrid KPL, 25x0.45 Plan achromat.JPG
non-raised half-hybrid KPL, 25x0.45 Plan achromat.JPG (102.77 KiB) Viewed 1851 times
profile of non-raised half hybrid KPL, 25x0.45 Plan.jpg
profile of non-raised half hybrid KPL, 25x0.45 Plan.jpg (73.81 KiB) Viewed 1851 times
A "full hybrid" was found to be almost as good as the "half hybrid".

Notes:
1) The color profile covers only the range of dense vertical bars of the scale, not the "window frame".
2) The idea is demonstrated here https://www.microbehunter.com/microscop ... 76#p102276

PeteM
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Re: "Hybrid" 160mm TL Zeiss KPL eyepiece projection photography

#2 Post by PeteM » Sun Apr 11, 2021 8:31 pm

That looks to be a very good result. Thanks for sharing it.

Do the Zeiss KPL 8x lower half and 10x upper half simply screw together for the spacing you used?

Hobbyst46
Posts: 4277
Joined: Mon Aug 21, 2017 9:02 pm

Re: "Hybrid" 160mm TL Zeiss KPL eyepiece projection photography

#3 Post by Hobbyst46 » Sun Apr 11, 2021 8:42 pm

PeteM wrote:
Sun Apr 11, 2021 8:31 pm
That looks to be a very good result. Thanks for sharing it.

Do the Zeiss KPL 8x lower half and 10x upper half simply screw together for the spacing you used?
Yes, they do. Both are Huygens type, I believe, and belong in the same "series".

MicroBob
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Re: "Hybrid" 160mm TL Zeiss KPL eyepiece projection photography

#4 Post by MicroBob » Mon Apr 12, 2021 5:51 am

Hi together,
Rolf actually uses eye- and field lens of an KPL10 low eyepoint on the barrel or a KPL 8 low eyepoint. This is only a change of distance between the lens groups. For Leitz and Olympus he ended up with a more complex lens- and barrel mix.
By partially screwing in the lenses one could do some fine adjustment.

The KPLs are not simple Huygens eyepieces but contain one or two cemented lens groups - they couldn't delaminate otherwise and were no true Zeiss West products! :roll:
The C eyepieces might be Huygens eyepieces, I have never seen one delaminate.

Bob

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