crossed Nicol on SM2 setup

[Darionett]

Hello and happy Saturday to all of you.

I'm interested in implementing a crossed Nicol system in my Setup, which includes an SM2 tube system, ITL200 (Clone), and Mitutoyo M Plan Apo (Clone), as shown on closeuphotography.com.

In this particular system, where should the circular polarizer be placed in order to obtain the best optical performance? Between the sensor and ITL200 or between ITL200 and Mitutoyo lens? Thank you in advance for your answer. I already have an idea of how to rotate the filter freely inside the SM2 tubes without them having contact with the outside of the tubes, so there would be no stray light.

Best regards,
Dario

[Scarodactyl]

Filters should always go in the infinity space between the objective and tube lens if possible.

[Darionett]

Filters should always go in the infinity space between the objective and tube lens if possible.

Thank you

[Darionett]

New day, new doubts (mainly due to my ignorance on the subject). Now that I have a plan for the project, I am faced with a technical question, which type of circular polarizer should I use? I have seen some filters, but I have no idea which one I need for my type of photography (insects with shiny exoskeletons, minerals, reflective surfaces). Could someone explain to me what would be the ideal extinction ratio? Thanks.

[Pau]

Extinction ratio must be as high as possible. Another important aspect is the color hue when crossed: many camera pol filters induce a strong blue (or other colors) hue, the general hue is easily corrected but if it is mainly in the highlights (very usual) it will be more annoying.
From all my (old) camera pols only one of them (B+W) is really color neutral while all my microscope ones are neutral excepted few cheapo plastic ones
In general microscope dedicated filters are preferable because they are designed to work crossed. Edmund Optics Techpec filters are very good (although not inexpensive).

In principle you don't need circular pols for microscopy as you are not going to use old style camera AF sensors, do you?

[Scarodactyl]

The depolarizer still helps with some setups and almost all microscope analyzers have them.

[Pau]

The depolarizer still helps with some setups and almost all microscope analyzers have them.

Sure, for example I can see some differences between the two visual ways of the trinocular head when rotating an analyzer without depolarizer but I think that Dario has a "macro style" setup, not a complete microscope, and AFAIK this isn't relevant, what's your opinion in this case?

[Scarodactyl]

It probably does not matter in this case but it probably does not hurt either.

[Darionett]

Extinction ratio must be as high as possible. Another important aspect is the color hue when crossed: many camera pol filters induce a strong blue (or other colors) hue, the general hue is easily corrected but if it is mainly in the highlights (very usual) it will be more annoying.
From all my (old) camera pols only one of them (B+W) is really color neutral while all my microscope ones are neutral excepted few cheapo plastic ones
In general microscope dedicated filters are preferable because they are designed to work crossed. Edmund Optics Techpec filters are very good (although not inexpensive).

In principle you don't need circular pols for microscopy as you are not going to use old style camera AF sensors, do you?

In my specific case, I use a Nikon D7100, with extension tubes, a 200mm tube lens, and a microscope objective. Therefore, I can use a linear polarizer, which makes everything simpler.
I found linear polarizers with an extinction ratio of 1000:1. Would they be suitable?

[Pau]

Yes, it will be

[Darionett]

Yes, it will be

Thank you Pau and thanks to everyone who has reply to this post, you are helping me with my project