Painting in different wavelengths

[StephanN]

So, slowly ticking off a few indoor-things on my to-do list before the summer season fully kicks in, I've turned my attention to a painting which I've wanted to take photos of for some time. I bought the harbour-painting years ago at a discount when a local art shop went bust; must have been at some point during the 1990's. According to this article, it's a fake: https://www.walesonl...ns-most-2080619 (apparently, the artist only signs on the back of the paintings), so I won't be able to sell it and retire on the proceeds

 

The second painting (the one with the ship-wreck), however, is genuine, as I purchased it directly from the artist

 

The equipment used is as follows:

• VIS: Canon, EOS 5DSR, Canon EF 24-70mm
  
• UV1: Canon EOS 6D, b/w-conversion, internal X330C, external S8612, Steinheil München Cassar-S 50mm
  
• UV2: Canon EOS 6D, full spectrum, UV-filter by Optik Macario, Steinheil München Cassar-S 50mm
  
• IR: Canon EOS 6D, converted to 700 nm, Canon EF 24-70mm
  

Post was minimal, mainly cropping (which made me realise that I hadn't aligned the sensor fully parallel to the paintings). The shots with the LEDs display some uneven lighting, which is due to my wobbly handling of the torches. That's why I took the control shots with the full frontal FS-flash.

 

I. Harbour (whoever painted this)

 

1. Visible light, room-lights

 

2. Visible light, UV-LED (Nemo)

 

3. IR, room-lights, WB grass

 

4. IR, 850nm-LED, WB same as 3

 

5. IR, 940nm-LED, WB same as 3

 

6. IR, UV-LED (Nemo)

 

7. UV1, UV-LED (Nemo), light-painting, standing slightly to the left of the camera

 

8. UV1, FS-Flash (Yongnuo YN560-III), flash held over the camera, pointed directly at the canvas

 

9. UV2, FS-Flash (Yongnuo YN560-III), flash held over the camera, pointed directly at the canvas, WB in-camera from PFTE

 

10. same as 9, converted to b/w in Lightroom

 

 

II. Shipwreck (Romana Rachbauer)

 

1. Visible light, room-lights

 

2. Visible light, UV-LED (Nemo)

 

3. IR, room-lights, WB grass

 

4. IR, 850nm-LED, WB same as 3

 

5. IR, 940nm-LED, WB same as 3

 

6. IR, UV-LED (Nemo)

 

7. UV1, UV-LED (Nemo), light-painting, standing slightly to the left of the camera

 

8. UV1, FS-Flash (Yongnuo YN560-III), flash held over the camera, pointed directly at the canvas

 

9. UV2, FS-Flash (Yongnuo YN560-III), flash held over the camera, pointed directly at the canvas, WB in-camera from PFTE

 

10. same as 9, converted to b/w in Lightroom

[colinbm]

Fascinating to see the differences in the different lights, thanks for sharing.

I have too many questions on the setup of the lightings, but I think I get it.

I will wait for others to comment & see how this pans out.

[StephanN]

I have too many questions on the setup of the lightings

 

Go on then, ask away

[Stefano]

You seem to have false yellows and false lavenders in UV, so the reflectance of some pigments may have a bump at 360-370 nm.

[StephanN]

You seem to have false yellows and false lavenders in UV, so the reflectance of some pigments may have a bump at 360-370 nm.

 

Oh no, let's not go down the road of determining wavelengths via colour. Wasn't there a thread just a couple of days ago, where this idea was torn to pieces

 

What I find interesting in the harbour-painting is, how different the UV1- and UV2-photos are (8 and 10). It may be in part due to slightly different angles of the flash, so I ought to repeat these shots with the flash mounted on the camera, I'm not sure why I didn't think of this in the first place

[dabateman]

I like how the four boats on the left are clearly made up of different paints than one would expect from the visible image.

In IR they almost disappear. But in UV the two front are dark and the back ones are light.

You can see some of the different paint layers with this analysis. Quite interesting.

I think I have silk screen I will have to investigate.