Even DF illumination for 4x objective

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mrlowndes
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Joined: Fri Sep 19, 2014 11:04 am

Even DF illumination for 4x objective

Post by mrlowndes »

Anyone got any advice on how to get great DF on a 4X objective that evenly illuminates the whole field? I have a Nikon Optiphot, but I have heard that some Olympus condensers are easy to adapt to the Nikon dovetail for the substage condenser, and that the olympus condensers have a filter tray for a DF patch stop. Any thoughts?

Alan Wood
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Re: Even DF illumination for 4x objective

Post by Alan Wood »

The Olympus condenser dovetail is slightly bigger than the Nikon one. It is definitely possible to use Nikon condensers on Olympus microscopes; I used a Nikon dark-ground condenser on my BH-2 until I found a cheap Olympus one. It may not be possible to use Olympus condensers on Nikon microscopes, I have not tried.

Nikon condensers are usually cheaper than Olympus ones.

Olympus say that their dark-ground condensers are for 10-40× (BH2-DCD) and 10-100× (BH2-DCW).

Olympus condensers for the BH-2 and BX do NOT have a filter tray.

On the rare occasions that I want 4× dark-ground, I use my CK2 inverted microscope with the 40× phase annulus.

Alan Wood

dolmadis
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Re: Even DF illumination for 4x objective

Post by dolmadis »

Alan Wood wrote:
Fri Feb 05, 2021 3:09 am
The Olympus condenser dovetail is slightly bigger than the Nikon one. It is definitely possible to use Nikon condensers on Olympus microscopes; I used a Nikon dark-ground condenser on my BH-2 until I found a cheap Olympus one. It may not be possible to use Olympus condensers on Nikon microscopes, I have not tried.
Which Nikon series condensers fit, Alan?

Thanks, John

Pau
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Re: Even DF illumination for 4x objective

Post by Pau »

DF with a 4X usually is easy, you don't need a dedicated DF condenser if you can place a stop at the right position in an ordinary BF condenser of using a Phase Contrast ring for higher NA objectives as Alan does.

Dedicated DF condensers are designed for high NA objectives where DF stops on BF condensers provide bad results or even when DF is just impossible with them, but its illuminated field can be too small for a 4X

You can also get good DF even without condenser with a ring light in place of it or laterally illuminating the slide.
Pau

pbraub
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Re: Even DF illumination for 4x objective

Post by pbraub »

If you have Phase contrast a PH3 or PH2 ring should also provide DF on 4x.

Alan Wood
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Re: Even DF illumination for 4x objective

Post by Alan Wood »

dolmadis wrote:
Fri Feb 05, 2021 3:41 am
Which Nikon series condensers fit, Alan?
John

I do not have a Nikon catalogue that shows their condensers with a circular dovetail fitting, so I do not know exactly which dark-ground condenser I had.

I still have a Nikon Achromat NA 0.85 condenser that fits my BH-2, but I don't know its model name or code. It is taller than Olympus condensers, and can push up the slide if I am not careful.

I guess most Nikon condensers would fit the Olympus dovetail. Large ones like phase contrast and DIC might not fit.

Alan Wood

mrlowndes
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Re: Even DF illumination for 4x objective

Post by mrlowndes »

Alan Wood wrote:
Fri Feb 05, 2021 3:09 am
The Olympus condenser dovetail is slightly bigger than the Nikon one. It is definitely possible to use Nikon condensers on Olympus microscopes; I used a Nikon dark-ground condenser on my BH-2 until I found a cheap Olympus one. It may not be possible to use Olympus condensers on Nikon microscopes, I have not tried.

Nikon condensers are usually cheaper than Olympus ones.

Olympus say that their dark-ground condensers are for 10-40× (BH2-DCD) and 10-100× (BH2-DCW).

Olympus condensers for the BH-2 and BX do NOT have a filter tray.

On the rare occasions that I want 4× dark-ground, I use my CK2 inverted microscope with the 40× phase annulus.

Alan Wood
I found a $30 adapter that might let me fit an Olympus condenser onto my optiphot. It's in the post so i'll let you know if it works (although I don't have an Olympus condenser yet, either). I have read that the Olympus Aplanat Achromat condenser can have the top lens unscrewed and patch stop placed for DF and there are Olympus Aplanats available for $300 on Ebay. Is it possible to unscrew the top element of a Nikon Aplanat? - also, the only Nikon Aplanat condenser listed on Ebay is $800!

Further, there are vintage Olympus Aplanat condensers that have very large top elements, so they may accommodate 4X DF without the need to remove top element.

mrlowndes
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Re: Even DF illumination for 4x objective

Post by mrlowndes »

Pau wrote:
Fri Feb 05, 2021 4:04 am
DF with a 4X usually is easy, you don't need a dedicated DF condenser if you can place a stop at the right position in an ordinary BF condenser of using a Phase Contrast ring for higher NA objectives as Alan does.

Dedicated DF condensers are designed for high NA objectives where DF stops on BF condensers provide bad results or even when DF is just impossible with them, but its illuminated field can be too small for a 4X

You can also get good DF even without condenser with a ring light in place of it or laterally illuminating the slide.
I have a PC turret condenser, but it does not cover 4X

Several people have told me about these illusive ring lights, but I'm failing to find any on ebay. Also, I would be concerned with LED ring lights for several reasons: 1 - They would pick up too many marks and scratches on slide and coverslips for good DF. 2 - Cheap LEDs are never worth the money. I would need a CRI of at least 85 because I want to shoot video and have accurate colors. 3 - Cheap LED often cause flickering or banding in video. 4. I have a fiber ring light designed for stereo microscopes so is far too big for my compound microscope stage. I think this combination of requirements makes the "right" LED ring light as rare as rocking horse poop

Pau
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Re: Even DF illumination for 4x objective

Post by Pau »

I have a PC turret condenser, but it does not cover 4X
Can you remove the condenser upper lens?
With my Zeiss condensers it is needed anyway for 4X and less. Some models allow to switch it out and others to unscrew it.
Abbe condensers usually cover the 4X with the upper lens although with some models is still convenient to remove it for low power while others don't allot it at all
Pau

mrlowndes
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Re: Even DF illumination for 4x objective

Post by mrlowndes »

Pau wrote:
Fri Feb 05, 2021 11:51 am
I have a PC turret condenser, but it does not cover 4X
Can you remove the condenser upper lens?
With my Zeiss condensers it is needed anyway for 4X and less. Some models allow to switch it out and others to unscrew it.
Abbe condensers usually cover the 4X with the upper lens although with some models is still convenient to remove it for low power while others don't allot it at all
Yeah, I can remove the condenser lens, but that is the only glass part of the whole thing - then it would just be the patch stop and the field lens for illumination. I will try it

Saul
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Re: Even DF illumination for 4x objective

Post by Saul »

mrlowndes wrote:
Thu Feb 04, 2021 9:02 pm
Anyone got any advice on how to get great DF on a 4X objective that evenly illuminates the whole field? I have a Nikon Optiphot, but I have heard that some Olympus condensers are easy to adapt to the Nikon dovetail for the substage condenser, and that the olympus condensers have a filter tray for a DF patch stop. Any thoughts?
There is extra lens (do not remember part #), which has to placed into the condenser's light entrance. I had the same problem with low magnification


IMG_2130-web685x950U100-G14.jpg
Saul
μ-stuff

mrlowndes
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Joined: Fri Sep 19, 2014 11:04 am

Re: Even DF illumination for 4x objective

Post by mrlowndes »

Saul wrote:
Fri Feb 05, 2021 1:58 pm
mrlowndes wrote:
Thu Feb 04, 2021 9:02 pm
Anyone got any advice on how to get great DF on a 4X objective that evenly illuminates the whole field? I have a Nikon Optiphot, but I have heard that some Olympus condensers are easy to adapt to the Nikon dovetail for the substage condenser, and that the olympus condensers have a filter tray for a DF patch stop. Any thoughts?
There is extra lens (do not remember part #), which has to placed into the condenser's light entrance. I had the same problem with low magnification



IMG_2130-web685x950U100-G14.jpg
Thanks - would be great to know what this is called so I can search for it

mrlowndes
Posts: 23
Joined: Fri Sep 19, 2014 11:04 am

Re: Even DF illumination for 4x objective

Post by mrlowndes »

mrlowndes wrote:
Fri Feb 05, 2021 2:28 pm
Saul wrote:
Fri Feb 05, 2021 1:58 pm
mrlowndes wrote:
Thu Feb 04, 2021 9:02 pm
Anyone got any advice on how to get great DF on a 4X objective that evenly illuminates the whole field? I have a Nikon Optiphot, but I have heard that some Olympus condensers are easy to adapt to the Nikon dovetail for the substage condenser, and that the olympus condensers have a filter tray for a DF patch stop. Any thoughts?
There is extra lens (do not remember part #), which has to placed into the condenser's light entrance. I had the same problem with low magnification



IMG_2130-web685x950U100-G14.jpg
Thanks - would be great to know what this is called so I can search for it
Aha! C-CEL expander lens

mrlowndes
Posts: 23
Joined: Fri Sep 19, 2014 11:04 am

Re: Even DF illumination for 4x objective

Post by mrlowndes »

mrlowndes wrote:
Fri Feb 05, 2021 2:31 pm
mrlowndes wrote:
Fri Feb 05, 2021 2:28 pm
Saul wrote:
Fri Feb 05, 2021 1:58 pm

There is extra lens (do not remember part #), which has to placed into the condenser's light entrance. I had the same problem with low magnification



IMG_2130-web685x950U100-G14.jpg
Thanks - would be great to know what this is called so I can search for it
Aha! C-CEL expander lens
oh no that's not it

Saul
Posts: 1781
Joined: Mon Jan 31, 2011 11:59 am
Location: Naperville, IL USA
Contact:

Re: Even DF illumination for 4x objective

Post by Saul »

Aha! C-CEL expander lens...
.................
oh no that's not it
Found my old link - https://www.photomacrography.net/forum/ ... 98#p250598
But no part number ...
Saul
μ-stuff

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