Newton Upper Falls (980nm BP10 filter)

[Andy Perrin]

Here's Newton Upper Falls (Newton, Massachusetts, US) at 980nm (the water dark spot). The image is a panorama.

 

Each photo was F8, 15 sec, ISO100 with only indirect sunshine unfortunately. I would really like to see what happens if I try a polarizer stacked with the 980nm filter...

 

 

Crop of pano:

 

iPhone pano:

[ulf]

Interesting pictures, Andy!

 

I would really like to see what happens if I try a polarizer stacked with the 980nm filter...

Be prepared to use an expensive specialist polariser for IR.

 

Normal polarisers begin to lose their ability to polarise light above 700nm.

This is a spectrogram of my brown-tinted Polaroid® glasses:

 

They work by the book up to about 650nm

The transmission of an ideal functioning polariser is maximum 50%, disregarding the surface losses.

[Andy Perrin]

Thanks! Yeah, I had figured I would need something like that. I tried my polarizer earlier with the 980nm filter and it failed to work at all. I could get no reduction in reflection off the surface of a glass of water.

[ulf]

This is not painfully expensive and could be worth to try out:

https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=7081&pn=LPNIRE2X2

More ambitious ring mounted variants are often one magnitude more expensive

[dabateman]

Andy,

Go through this review, look at all the filter curves. One maybe a winner at your wavelength:

 

https://www.lenstip.com/115.9-article-Polarizing_filters_test_B+W_EW_KSM_C-POL_MRC_72_mm.html

[dabateman]

Ok skimmed through them all. They all break at 800nm. So not going to work for you.

 

I somehow remember Shane mentioning that the Breakthrough CP was good in IR. Maybe look that one up. I think theirs is X4 or some odd name.

 

I still can't find a spectrum for the polar pro quartz line filters.

[Andy Perrin]

This is not painfully expensive and could be worth to try out:

https://www.thorlabs...81&pn=LPNIRE2X2

More ambitious ring mounted variants are often one magnitude more expensive

 

I was thinking this one ("LPNIRE100-B - Ø1" Linear Polarizer with N-BK7 Windows, 600-1100 nm") instead:

https://www.thorlabs...ctgroup_id=4984

[ulf]

Thorlabs:

Note: these polarizers are not designed for imaging applications due to internal scatter and relatively larger wavefront distortion. For polarizers with minimal scatter, please see our Nanoparticle Linear Film Polarizers.

[dabateman]

Those are an order of magnitude more expensive.

May want to message Shame and see if the Breakthrough CP will work.

 

[Andy Perrin]

Thorlabs:

Note: these polarizers are not designed for imaging applications due to internal scatter and relatively larger wavefront distortion. For polarizers with minimal scatter, please see our Nanoparticle Linear Film Polarizers.

I saw that, UlfW, but it's the same stuff as the one you linked, just between some glass. I'm willing to try them and tolerate less than perfect image quality in the name of not spending $300.