unmount polarizer filters

iconoclastica · Post by **iconoclastica** » Mon Dec 03, 2018 6:40 am

Some weeks ago I bought a pandora's box full of parts and accessories said to belong to the Optiphot. Among these are three polarizer filters:

As such, I have no use for them. But for the epi-illuminator that came last wekend, I do have the analyzer slider (from the same box

), however, without filter. The glass in the filters is 20mm, so they should be usable in the analyzer. Only they have been securely fixed into their rings by some half-transparent greyish kit. Can this be dissolved so the glass comes out?

(BTW, the right filter has a kind of horizontal axle: in what kind of application does one need that?)

iconoclastica · Post by **iconoclastica** » Mon Dec 03, 2018 2:05 pm

All right, that was easier than it appeared beforehand. The glass disk is a little smaller than the mount. The furrow in between filled with a kind of rubber cement. Under the stereo microscope it is doable to cut with the point of a surgeon's knife through the furrow and remove most of the rubber cement. Then the disk can carefully be levered out of its mount.

genera · Post by **genera** » Mon Dec 03, 2018 3:16 pm

iconoclastica wrote: . . .
(BTW, the right filter has a kind of horizontal axle: in what kind of application does one need that?)

The last filter should fit one of the drop-in filter slots available on many Optiphot vertical illuminators. The pins keep it from falling too far into the slot and the screw provides a convenient handle for removing a possibly very hot filter.

iconoclastica · Post by **iconoclastica** » Tue Dec 04, 2018 1:49 am

The last filter should fit one of the drop-in filter slots available on many Optiphot vertical illuminators. The pins keep it from falling too far into the slot and the screw provides a convenient handle for removing a possibly very hot filter.

Yes indeed, that fits. Must be combined with a rotatable analyzer then?

genera · Post by **genera** » Tue Dec 04, 2018 9:11 am

If you want adjustable cross polarization, yes.

Have you verified that it is a polarizer and not a neutral density filter? It seems odd, to me, to put a polarizer so close to the lamphouse and in a position with possibly depolarizing optics between it and the subject.

ChrisR · Post by **ChrisR** » Tue Dec 04, 2018 9:54 am

It's not reversible, is it, ie a circular pol one way and linear pol the other?

Try it in a mirror!

iconoclastica · Post by **iconoclastica** » Tue Dec 04, 2018 11:08 am

genera wrote:Have you verified that it is a polarizer

Yes, I have. Hold it in front of a computer sceen and see it turning black and bright again.

It's not reversible, is it, ie a circular pol one way and linear pol the other?
Try it in a mirror!

That's new to me. How shoud I try this and what should I see then?

ChrisR · Post by **ChrisR** » Tue Dec 04, 2018 11:29 am

Watch carefully - it's quick!
https://www.youtube.com/watch?v=6lVIo9C0NDA

A circular pol filter is a linear pol with a quarter wave plate on one side - the one which goes to the camera normally.
The qwp makes the polarization rotate, like a corkscrew as the wave travels, by making the electromagnetic wave out of phase with the electric field by 90º. The mirror reverses the direction of the rotation so when the light gets back to the filter it's blocked - the electric and electromagnetic waves are then 180º out of phase, and the plane of rotation is rotated by 90º.

If you have the retarder towards your eye instead of towards the mirror, the mirror gets plane pol light which it reflects in the same plane, so it's like you're looklking through two pol filters which are not crossed - just a couple of stops dimmed.

iconoclastica · Post by **iconoclastica** » Tue Dec 04, 2018 2:56 pm

I don't see any difference looking through either side. In comparison, a photographic CPL made a lot of difference.

unmount polarizer filters

unmount polarizer filters

Re: unmount polarizer filters