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Goldfinch feather in UV, visible and IR

6 replies to this topic

#1 JMC

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Posted 09 August 2019 - 18:14

We get Goldfinches in the garden here. For those that don't know these lovely little birds, they are very colourful and are always chattering. Below is an image I took last year - 3 of them at the feeder.
Attached Image: 578A3841a_reduced.jpg

While in the garden a couple of days ago I found a small feather from one. So I did UV, visible and IR images of it.

Setup - Canon EOS 5DSR multispectral, Rayfact 105mm UV lens, single Bowens GM500 flash head with un-coated glass bulb at about 45 degrees to the camera.

UV - Baader U
Visible - BG39, 2.5mm (Chinese)
IR - Heliopan 715nm

Camera and lens settings different between the UV, vis and IR. Images captured as RAW and then whitebalanced from PTFE disc imaged with the different filters. Resized and cropped for here, but not further modified for brightness or contrast.

Visible
Attached Image: 1R4A9635 visible BG39 cropped small.jpg

UV
Attached Image: 1R4A9631 baader u cropped small.jpg

IR
Attached Image: 1R4A9645 heliopan 715 cropped small.jpg

Wasn't sure what to expect with the UV image, but there is still a hint of the yellow there. Can't really see any colour with the IR one.

#2 Cadmium

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Posted 09 August 2019 - 23:20

Jonathan, Quite nice shot of the finches in flight!
Interesting also that a touch of yellow shows up in the UV.

#3 Andy Perrin

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Posted 10 August 2019 - 00:26

I like the flying finches too. The UV is nifty.

#4 Andrea B.

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Posted 10 August 2019 - 01:37

Now isn't that interesting that the light/dark signature is the same in all three wavebands? I wonder if that means anything?
Andrea G. Blum
Often found hanging out with flowers & bees.

#5 enricosavazzi

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Posted 10 August 2019 - 06:52

A 715 nm cutoff of the NIR-pass filter is still quite close to VIS, so it is expected that some of the VIS pattern still shows. At 900 or 1,000 nm probably there is little or no trace of the VIS pattern.
-- Enrico Savazzi

#6 Cadmium

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Posted 10 August 2019 - 07:02

830/850nm is where it pretty much evens out. Anything above that is just for water darkness mostly.

#7 JMC

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Posted 10 August 2019 - 12:48

Thanks all. The image with 3 Goldfinches was a bit of luck to get them all in focus at the same time.

I've taken some more images with some more IR filters.

Heliopan 780
Attached Image: 1R4A9652 780 small.jpg

Heliopan 830
Attached Image: 1R4A9655 830 small.jpg

Heliopan 1000
Attached Image: 1R4A9660 1000 small.jpg