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Multispectral test with filter rings

Multispectral TriColour
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#1 Stefano

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Posted 16 June 2021 - 16:22

Finally, after years of having my filters attached to a cardboard/tape roll, I mounted them in appropriate filter rings. This improves versatility a lot.

I took a UV, VIS and IR image of a plant to test multispectral stacks. The filter rings allow me to change my filters without moving my camera (at least, reducing the forces on the lens).

I didn't refocus, and I didn't align the images, so enjoy some chromatic aberration. The paper tissue was used as a white balance target. UV, VIS and IR images white balanced in-camera, stacks white balanced in Photo Ninja (it provides better results than IrfanView).

This time I worked with .tif files, so the quality should be better.

Camera: full-spectrum Canon EOS M;
Lens: Soligor 35 mm f/3.5.

Filters:
UV: ZWB2 (2 mm) + Chinese BG39 (2 mm);
VIS: Chinese BG39 (2 mm);
IR: Hoya R72.

UV (f/8, ISO 100, 8 s exposure):
Attached Image: IMG_3334.jpg

VIS (f/8, ISO 100, 1/125 s exposure):
Attached Image: IMG_3336.jpg

IR (f/8, ISO 100, 1/60 s exposure):
Attached Image: IMG_3338.jpg

TriColour (IR = red, VIS = green, UV = blue):
Attached Image: UV+VIS+IR PN.jpg

IRG:
Attached Image: IRG PN.jpg

GBU:
Attached Image: GBU PN.jpg

Notes:
- My Chinese BG39 is not the best filter to cut UV/IR, because it doesn't cut UV at all (at least, most UV) and it suppresses the reds too much. But this is what I have at the moment.
- IRG and GBU should be quite known abbreviations here, but to recap:
An IRG image has infrared in the red channel, red in the green channel and green in the blue channel;
A GBU image has green in the red channel, blue in the green channel and UV in the blue channel.