Experimenting with oblique lighting, polarisation and phase contrast

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IanW
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Experimenting with oblique lighting, polarisation and phase contrast

#1 Post by IanW » Sat Apr 29, 2017 4:24 pm

I have spent some time getting my act together and think I am getting there. Today I am using a Zeiss Jena NF with pancratic zoom condenser converted to LED lighting, with a Nikon d810 attached. A few drops of water from my pond was my subject today. For the polarised lighting I am using the PACO filter (Pack Advanced Contrast Optic). Here are some results (cropped). The last two are single shots, whereas first three are stacks of around 3 to 6 images using Zerene.

Numbers one, two and three are using LOMO WI 70X 1.23 , numbers four and five using Zeiss 40X 0.95 Planapo.

Imagecrop by Fortesmentum, on Flickr

Imagecropped by Fortesmentum, on Flickr

Imagecrop by Fortesmentum, on Flickr
ImageDSC_0103_DxO by Fortesmentum, on Flickr
ImageDSC_0105_DxO by Fortesmentum, on Flickr
Zeiss Jena NF, Zeiss Standard 18 and WL

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zzffnn
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Re: Experimenting with oblique lighting, polarisation and phase contrast

#2 Post by zzffnn » Sat Apr 29, 2017 10:09 pm

Nice images.

Are photos #1, #4 and #5 COL (circular oblique light)? The blue background were provided by PACO, correct?

Thank you for sharing.

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75RR
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Re: Experimenting with oblique lighting, polarisation and phase contrast

#3 Post by 75RR » Sat Apr 29, 2017 10:28 pm

Getting good Oblique in photos 1,3,4 and 5
Number 2 however is my favorite, is that a type of phase?
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JimT
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Re: Experimenting with oblique lighting, polarisation and phase contrast

#4 Post by JimT » Sat Apr 29, 2017 11:05 pm

I am not sure which is which. I like number four the best which looks like oblique lighting. What technique did you use?

Is the third one the polarized and did you have one filter below the specimen and the other one above? I would have expected more birefringence.

BTW, really nice camera.

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75RR
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Re: Experimenting with oblique lighting, polarisation and phase contrast

#5 Post by 75RR » Sat Apr 29, 2017 11:37 pm

BTW, really nice camera.
That got me curious ... is that the plain one or the FX ?

https://www.amazon.com/Nikon-D810-DSLR- ... Nikon+D810

https://www.amazon.com/Nikon-D810-FX-fo ... B00LAJQVR6
Zeiss Standard WL (somewhat fashion challenged) & Wild M8
Olympus E-P2 (Micro Four Thirds Camera)

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Re: Experimenting with oblique lighting, polarisation and phase contrast

#6 Post by IanW » Sun Apr 30, 2017 11:33 am

zzffnn wrote:Nice images.

Are photos #1, #4 and #5 COL (circular oblique light)? The blue background were provided by PACO, correct?

Thank you for sharing.
Hi zzffnn. The oblique lighting is simply created by offsetting the light path before entering the pancratic condenser. On the Zeiss Jena NF this is achieved by offsetting illumination light path of iris diaphragm which is mounted on the light base and can be rotated 360 degrees both CW or CCW.


Image20170430_115426 by Fortesmentum, on Flickr

Yes the blue effect is created by the P.A.C.O system. As well as the polarising filters there are two further filters (transparent crystal polystyrene resin under tension) which can be rotated for different lighting and contrast effects.


The creator of the P.A.C.O system has a facebook page - but it is in Spanish.
https://www.facebook.com/pg/P.A.C.O.CLU ... e_internal
Last edited by IanW on Sun Apr 30, 2017 11:49 am, edited 1 time in total.
Zeiss Jena NF, Zeiss Standard 18 and WL

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Re: Experimenting with oblique lighting, polarisation and phase contrast

#7 Post by IanW » Sun Apr 30, 2017 11:39 am

75RR wrote:Getting good Oblique in photos 1,3,4 and 5
Number 2 however is my favorite, is that a type of phase?
Thanks 75RR. Yes number 2 is using the LOMO 70X1.23 phase objective which thanks to the zoom-able pancratic condenser along with a phase ring placed on the light base, can achieve phase contrast with any phase objective.

Image20170430_123557 by Fortesmentum, on Flickr
Last edited by IanW on Sun Apr 30, 2017 11:48 am, edited 1 time in total.
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Re: Experimenting with oblique lighting, polarisation and phase contrast

#8 Post by IanW » Sun Apr 30, 2017 11:46 am

JimT wrote:I am not sure which is which. I like number four the best which looks like oblique lighting. What technique did you use?

Is the third one the polarized and did you have one filter below the specimen and the other one above? I would have expected more birefringence.



BTW, really nice camera.
Hi Jim. As explained above, the oblique lighting is through offsetting light path using the gadget sitting on top of the light source. It is also rotatable, so can be used using a polarising filter etc sitting on top. One filter is below specimen, the other above. Greater interference can be created - I'm just getting to grips with using this system on the NF scope - previously I was using it with success on my Zeiss Standard 18 - where it attached nicely beneath the condenser. On the NF this isn't possible so I will need to rig something up to get the best out of it.

Here's a shot using the PACO system on my Zeiss Standard 18 with 25X neofluar

ImageDSC_0003_DxO by Fortesmentum, on Flickr
75RR wrote:
BTW, really nice camera.
That got me curious ... is that the plain one or the FX ?

https://www.amazon.com/Nikon-D810-DSLR- ... Nikon+D810

https://www.amazon.com/Nikon-D810-FX-fo ... B00LAJQVR6
75RR - the d810 is FX. It has a front curtain shutter and the mirror can be locked up, so along with a delayed shutter release is ideal for photo-microscopy.
Last edited by IanW on Sun Apr 30, 2017 6:45 pm, edited 3 times in total.
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75RR
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Re: Experimenting with oblique lighting, polarisation and phase contrast

#9 Post by 75RR » Sun Apr 30, 2017 12:39 pm

75RR - the d810 is FX. It has a front curtain shutter and the mirror can be locked up, so along with a delayed shutter release is ideal for photo-microscopy
Very nice! Congratulations.
Zeiss Standard WL (somewhat fashion challenged) & Wild M8
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Re: Experimenting with oblique lighting, polarisation and phase contrast

#10 Post by zzffnn » Sun Apr 30, 2017 1:30 pm

Thanks, IanW.

Can you achieve good COL with your pancratic condenser and the LOMO 70/1.23? In some cases, well executed COL (with flares suppressed) can produce even better images that offset oblique.

However, I remember an experienced owner who told me that the pancratic condenser does not work well at high NA. Do you feel the same? Your images look very good though.

Is there a positive lens inside the bottom field lens attachment or condenser bottom? That would bring the masks closer to front focal plane of condenser.

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Re: Experimenting with oblique lighting, polarisation and phase contrast

#11 Post by IanW » Sun Apr 30, 2017 5:45 pm

75RR wrote:
Very nice! Congratulations.
But it's big and heavy. I spent the seventies and eighties using an Olympus OM-1, so this is a shock to the system:-)
zzffnn wrote:Thanks, IanW.

Can you achieve good COL with your pancratic condenser and the LOMO 70/1.23? In some cases, well executed COL (with flares suppressed) can produce even better images that offset oblique.

However, I remember an experienced owner who told me that the pancratic condenser does not work well at high NA. Do you feel the same? Your images look very good though.

Is there a positive lens inside the bottom field lens attachment or condenser bottom? That would bring the masks closer to front focal plane of condenser.
I've not tried COL but will do so some time and report back.

As you know I was having some problems with alignment of the pancratic condenser which I've now sorted by nudging the alignment plate. It seems to be performing well with high numerical apertures, although I could do with a slightly more powerful light source.

I'm not sure what you mean by positive lens. there's no filter holder as such - so I place filters on top of the diaphragm carrier on the base. Perhaps you could explain a little more for me:-)
Zeiss Jena NF, Zeiss Standard 18 and WL

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Re: Experimenting with oblique lighting, polarisation and phase contrast

#12 Post by gekko » Thu May 04, 2017 3:00 pm

Very nice images.

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