NIKON Plan APO 20X / 0.75 0.17 with and without cover slip

[Adalbert]

Hello everybody,

Bob has already shown some photographs taken using this lens:
https://www.photomacrography.net/forum/ ... highlight=

My first test-photo:
- EOS M3 (crop)
- DCR-150 focused to infinity (as for Mitties).
- NIKON Plan APO 20X / 0.75 DIC N2/ 0.17 WD 1.0 without cover slip
- Some black lines printed by the color laser printer
- 240 single shots a DOF/3

https://live.staticflickr.com/65535/495 ... d86c_o.jpg

BR, ADi

[JH]

Hi Adalbert
I have been thinking about this lens. Thanks for testing it. Have you tried to see the difference in image quality with different distances between the tube lens and the sensor? If you have, it would be nice to se the results.

I have posted my testing with the Nikon Plan apo 20x NA 0.75 finite 160mm lens on the forum https://www.photomacrography.net/forum/ ... 165#256165 and on my webpage. Changing the distance between the sensor and the objective have a significant effect. Without a coverslip my finite objective works best if the distance to sensor is increased approximately 4 cm (from 150 mm to 190 mm).


Best regards
Jörgen Hellberg

[viktor j nilsson]

Hi Adalbert
I have been thinking about this lens. Thanks for testing it. Have you tried to see the difference in image quality with different distances between the tube lens and the sensor? If you have, it would be nice to se the results.

I have posted my testing with the Nikon Plan apo 20x NA 0.75 finite 160mm lens on the forum https://www.photomacrography.net/forum/ ... 165#256165 and on my webpage. Changing the distance between the sensor and the objective have a significant effect. Without a coverslip my finite objective works best if the distance to sensor is increased approximately 4 cm (from 150 mm to 190 mm).


Best regards
Jörgen Hellberg

Interesting test, Jörgen. I too have the same 160m finite Nikon PlanApo 20x 0.75 objective, but I've only used it as intended with a cover slip on the microscope. It is certainly very very sharp when used with a cover slip. While the change in tube length certainly improved the image quality, it is nowhere near what you get with a cover slip. I personally wouldn't even consider using either the finite or infinity type 20x 0.75 objectives without a coverslip.


On that note, has anyone been able to compare the IQ of the NIKON Plan APO 20X / 0.75 Infinity-type against the 160mm version when used on a microscope with a coverslip and transmitted light?

Even at $100, I don't think I'll ever add a tube lens to my microcope. But it would be interesting to see how good the modern objevtive is compared to the old. I am guessing that the greatest difference will be in field coverage, rather than resolution/CA control.

[JH]

Thanks for the comment

I personally wouldn't even consider using either the finite or infinity type 20x 0.75 objectives without a coverslip.

That depends on what you want to photograph and finding a way to do it with the gear you have. For me it started with curiosity and this post 2015 https://www.photomacrography.net/forum/ ... 153#179153

A few years later I can conclude that this unorthodox use of the finite lens have served me well and therefore I am interested to find out what can be done with the 20x infinite.

But it would be interesting to see how good the modern objevtive is compared to the old. I am guessing that the greatest difference will be in field coverage, rather than resolution/CA control.

Do not forget the possibility to use the infinity space between the objective and the tube lens.

Best regards
Jörgen Hellberg

[viktor j nilsson]

Thanks for the comment

I personally wouldn't even consider using either the finite or infinity type 20x 0.75 objectives without a coverslip.

That depends on what you want to photograph and finding a way to do it with the gear you have. For me it started with curiosity and this post 2015 https://www.photomacrography.net/forum/ ... 153#179153

A few years later I can conclude that this unorthodox use of the finite lens have served me well and therefore I am interested to find out what can be done with the 20x infinite.

But it would be interesting to see how good the modern objevtive is compared to the old. I am guessing that the greatest difference will be in field coverage, rather than resolution/CA control.

Do not forget the possibility to use the infinity space between the objective and the tube lens.

Best regards
Jörgen Hellberg

Those older photos, especially the blue/black ones (blåvinge?) looks pretty good. I think they look sharper than your Issoria lathoni pictures, do you agree?

I agree about the usefulness of the infinity space. I am currently making a DIY dic setup, and it is a little restrictive to work with finites, I agree. I have
thought about picking up a Nikon Infinity objective and building more of a "optical bench" setup, but I haven't yet given up on the idea of making it work on my old finite microscope.


Sorry for hi-jacking the thread, Adalbert. Keep sharing your results!

[Adalbert]

Hello everybody,
This time with cover slip:

https://live.staticflickr.com/65535/495 ... 1b84_o.jpg

BTW, my Harley has been used => 200mm between chip and DCR-150 and 65mm between DCR-150 and microscope lens.

BR, ADi

[Lou Jost]

MUCH better, not surprisingly.

[Adalbert]

Hello Lou,
Please take a look at the not scaled version of the photo without cover slip.
It is not really bad. The resolution is OK.
BR, ADi

[ChrisR]

Fun getting the light in with such short WD?!?

Is the slip just resting on the paper?


I once tried fixing a coverslip to an objecting, figuring that it shouldn't matter where it went.
It didn't work for me - flare and fogging everywhere, but I didn't persist. Perhaps if the edges of the slip had been painted black it might have worked.

[Lou Jost]

Yes, I see, it's not terrible, but the other shot is much more contrasty.

[JKT]

The latter picture looks rather nice. What is the field coverage of these?

The price seem rather low - what is the catch? The part about cover slip doesn't bother me as I'm thinking of GP slides of micromoths. Neither does the working distance in that application. Anything else I should be aware of?

[Lou Jost]

I think these are great objectives. No catch, there is just an oversupply in the market because of decomissioned last-generation DNA analyzing equipment. However, the unmarked ones have unusual coverslip requirements, as discussed at length elsewhere on the forum.

[JKT]

Thanks Lou! I'll have to do my part in reducing the oversupply. I'll stick with the standard ones.

[Adalbert]

Hello Chris,
I have used one of them:

In this way:


BR, ADi

[Lou Jost]

For dry subjects you should be using the #1.5 slips though, which are 0.16-0.19mm thick.

If you have mountant between the coverslip and the subject, then perhaps the #1 slips are better.