How on earth does UV or IR photography work on consumer digital cameras, when they have bayer filters

[akburk]

I hope this is in the right section.

 

I was looking at the bayer filter and wondered - if consumer cameras have red/blue/green filters affixed on them and are irremovable, how does IR and UV light get through these filters? The red, blue and green must have a tight bandpass of 610nm≤λ< 760nm, 500nm≤λ< 570nm and 450nm≤λ< 750nm respectively, if they were not and let light leak then the bayer filter would be useless.

 

I can see there being a leak on the red side of the filter into IR since they are adjacent in wavelength, but I can't on the UV side because the blue filter would need to be inclusive of purple to leak over to UV, which it does not - otherwise it would not be a blue filter.

[Stefano]

They pass also UV and IR. If you search on the web you can find a lot of images like the one here, made by UVP member JMC. The different transmissions of these filters at different wavelengths is what allows false colors in UV and IR photography.

[akburk]

Thank you! I love this community, it so refreshing to see those graphs. It would have been perfect if it was done with the a6300 sensor so I can see my own filters specification

[Stefano]

The Bayer filters response seems to be the same for most cameras. In UV, red is usually dominant around 360 nm, and at deeper wavelengths, usually below 340 nm green is dominant. In IR, the red, green and blue filters all become transparent above about 850 nm, and that's why IR photos taken with an 850 nm or deeper longpass filter are black and white.

[akburk]

Now I can see why UV is easily suppresed in consumer sensors while IR is passed easily.

[akburk]

I have used a 900nm filter for IR photos and all photos are black and white. It's great to know why

[JMC]

Can't remember if I shared my Sony A7 III conversion results on here. If not here's a link to it - https://jmcscientificconsulting.com/imaging/project-mirrorless-part-2-the-camera-conversion/

 

There are subtle differences between different sensors, but as Stefano mentioned, in the UV they are briefly similar.

[Stefano]

Jonathan did a very good job related to this: https://www.ultravioletphotography.com/content/index.php/topic/2580-build-thread-at-home-measurement-of-camera-uv-spectral-response

 

A long topic, but you may read it if it interests you.

[akburk]

I am very grateful to get those links, thank you. I was going to look for wavelength-sensitivity graphs for sony cameras but now I don't need to.

[Stefano]

Also, camera sensor in visible and infrared light under a microscope: https://www.ultravioletphotography.com/content/index.php/topic/4095-microscopy-of-a-monochrome-converted-camera-sensor

 

Half debayered sensor: https://www.ultravioletphotography.com/content/index.php/topic/3150-enhanced-uvb-sensitivity-in-monochrome-converted-eos-5dsr

 

https://www.ultravioletphotography.com/content/index.php/topic/2974-split-sensor-image-monochromemultispectral-at-the-same-time

 

There's a lot to look for in this forum.

[dabateman]

I learned that the dyes are mostly the same ones that fuji makes and sells to Sony and even Canon. At least for cameras within the last 6 ish years. The difference comes down to various coatings on the sensor coverglass on top of the color filter array.

I was surprised when Eric Fossum mentioned that to me in an email.

 

You can see and buy them here:

https://www.fujifilm.com/us/en/business/semiconductor-materials/image-sensor-color-mosaic/rgb