Low magnification microscopy questions

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JohnyM
Posts: 463
Joined: Tue Dec 24, 2013 7:02 am

Low magnification microscopy questions

Post by JohnyM »

I've already found a solution for condenser that's better than Nikon's Achro 0.13. It's very simple and cheap and works great, but objectives...

M Plans 1x and 2,5x vignette horribly on APS-C sensor, but they have nice ~10mm working distances. Can anyone say if biological CF or CFN 1x and CF or CF N PlanApo 2x also vignette? Still, they have quite short WD. So main question:

Are there any alternatives for low magnification microscopy of 2x or bellow magnifications? There are quite a few restrictions: Working distance should be no longer than ~50mm (microscope stage) , tube lenght is 150mm + adapters, and they should be adaptable to RMS nosepiece - so not too big.

I've been thinking about mounting Schneider Componon 180mm F5,6 (as infinity tube) on microscope turret and reverse another 180 on it.
In theory that should give me 1x/0.09 EF=5,6 objective which is better than any other microscope objective available. But i have no clue what working distance would be - is there any way to estimate it? I guess it also would be 160mm. which is way too large

Solution for ~2x would be reversing another tiny componon 80mm f5,6 on 180mm that would produce 2x/0.9 EF=11 which is almost on par with PlanApo 2x. Still no clue what working distance that would produce. I guess 60-70mm which approaches my acceptance limit.



Please dont answer with usual "why you need such low magnification for microscope". I need it.
Thanks for any other input tho!

Photomicro
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Joined: Sat Aug 12, 2017 11:01 am
Location: UK

Re: Low magnification microscopy questions

Post by Photomicro »

JohnyM wrote:I've already found a solution for condenser that's better than Nikon's Achro 0.13. It's very simple and cheap and works great, but objectives...
Perhaps you could share your solution.

Mike
regards, Mike.

Time flies like an arrow, fruit flies like bananas.

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ChrisR
Site Admin
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Post by ChrisR »

CF N PlanApo 2x also vignette?
Yes, pretty sure, from memory.

I don't see you getting a "normal" lens like a Componon 80mm to have a WD less than 80mm, which if it were a simple lens it would have at infinity. They aren't "simple" but they're not retrofocus or telephoto. so more like a thick simple lens.
A normal lens with a short enough FL would giive you too much M.
Chris R

JohnyM
Posts: 463
Joined: Tue Dec 24, 2013 7:02 am

Post by JohnyM »

@ChrisR - thanks for input. I've put my purchase plans on hold, until i can confirm if it covers APS-C sensor. I've seen some images on this forum made with those objectives, but obviously processed, and on black background.

Enlarger lenses are a mystery to me. None of those i've had achieved infinity at nominal distance. Usually ~ -20mm , hence my estimations above. My best guess is that flange focal distance is measured on some weird spot.

Meanwhile i've ordered super-cheap 1x and 2x from this seller:
https://www.ebay.com/itm/1X-2X-Achromat ... 2749.l2649

They cost next to nothing, and will fill holes in nospiece untill i'll know what to buy. I'll write how they perform when i'll get them.


Another idea i have in mind is mounting 150-180mm enlarger lens and attaching infinity objective to it. But i need to think this through yet. Actually i've nice microscope "with everything" and i've been thinking about converting it to infinity for some time.



@Photomicro
Solution is extremely simple and cheap. It's 58mm F2 russian made Helios objective.
It requires no adaptation, just place it on condenser carrier (Fits on Nikon/Olympus dovetail):
Image

Field diaphragm is represented sharply and with minimal chromatic abberation (on par with Nikon Achromatic Aplanatic 1.4):
Image

Aperture is represented sharply in objective backfocal plane (pardon my conoscopic microscopy). You can see PhL phase ring and condenser diaphragm:

Image

Coverage is as much as my microphot stage permits:
Image

Why it's better than Nikon 0.13?
-Bigger coverage than nikon...
-NA is 0.25 vs Nikons 0.13... So it's good for low mag but also objectives like PlanApo 4x/0.2 or Plan 10x /0.25
-Definately better corrected. I wouldnt say it's as good as Achromatic-Aplanatic, but not far behind. Better than Achromatic 0.13
-Practically for free vs hundreds of dollars for Nikon...
And most importantly for me...
I do some metalwork to achive this:
Image
Here's the trick: It is focusing by extension. Means i "zoom" on phase / darfield / oblique inserts and vary them by simple twist of focus ring.
It's gonna be awesome when i finish :D

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