Testing for Phase Correction

[jjg213]

Hi, There may have been a previous post, or reference to a source of testing information, there are snippets of info about using polarizing filters (linear or circular?), however, I am unable to find a complete instruction. Could someone please advise of a relatively simple technique?
Thank you, John

[mooreorless]

This is what I have read about this. Buy cheap pair of polarized sunglasses and loosen screw or just push out the lens of these sunglasses. Hold one lens at eyelens and the other at objective lens while looking through the objective end towards a window, in the daylight :-). Turn the glass lens at the objective around and watch the view if it gets dimmer and brighter the whole way around then it is supposed to be phase-coated, but if one half of the view gets brighter and one half gets darker it is not p-coated. Now if you have a porro -prism disregard all this nonsense.;)
Regards,Steve

[jjg213]

Thank you Steve. I will try it with two photographic filters that I have on some of my bins that I know to be phase corrected and then on the ones in question.
John

[Kevin Purcell]

Now if you have a porro -prism disregard all this nonsense.;)
Regards,Steve

Though if you try it you'll find the output of the porro is polarized ;)

That test is actually easier to do if you wear polarized sunglasses and either put another polarizer (sunglasses) over the objective or look at the blue sky oposite the sun (especially later in the day) where you'll find it is polarized (then you can rotate the bin).

One other thing I've noticed (with PC bins) is if you view a polarized scene (e.g. blue sky behind a bird) through polarized sunglasses you of course get different sky brightnesses and a very odd 3D view because the two barrels have the prisms rotated in opposite directions (so the roof edge isn't vertical or horizontal).

[jjg213]

Hi Steve,
I just realized that you wrote that you should look from the objective end. Re-testing is complete and most satisfactory.
Thanks again,
Regards, John