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Oil Painting in UV-Vis-IR


10 replies to this topic

#1 Andrea B.

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Posted 29 March 2014 - 03:30

I wanted to see what an oil painting looked like in UV and IR. Sometimes evidence of an underdrawing can be found showing how the artist sketched out the preliminary compositon, so I wanted to look for that.
I don't know if this painting was ever varnished.

The IR photograph showed a lot of detail because the IR penetrates the surface of most oil paints. However, I do not see any underdrawings in this painting.

Most details of the painting's subject were lost in the UV photograph which only shows some surface details such as brushstrokes.

Painting: Hughes Avenue, Bronx, 1948 by Xavier Barile.
Barile was an American artist who was associated with the early 20th century Ashcan School.

Equipment [Pentax K5-broadband + Asahi 85/4.5 Ultra-Achromatic-Takumar]

Visible Light [f/11 for 1/1.7" @160 in Indoor Sunlight with Baader UVIR-Block Filter]
Attached Image: PNTX0008pnCrop.jpg

Ultraviolet Light [f/11 for 15" @800 in Indoor Sunlight with Baader-U UV-Pass Filter]
Actually it was very overcast, so the exposure was longer than usual.
And my window glass attenuates some (but not all) UV.
Attached Image: PNTX0017pnCrop.jpg

Infrared Light [f/11 for 2.5" @160 in Indoor Sunlight with B+W 093 IR-Pass Filter]
Attached Image: PNTX0020pnCrop.jpg
Andrea G. Blum
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#2 nfoto

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Posted 29 March 2014 - 21:52

Can you combine these captures to a multispectral composite?

#3 Andrea B.

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Posted 30 March 2014 - 03:59

Red(vis) + Green(uv) + Blue(ir)
Attached Image: Rvis+Guv+Bir.jpg

Red(ir) + Green(uv) + Blue(vis)
Attached Image: Rir_Guv_Bvis.jpg

(255,128,0)IR + (0,255,128)Vis +(128,0,255)UV
Attached Image: Oir+GBvis+Puv.jpg
Andrea G. Blum
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#4 colinbm

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Posted 30 March 2014 - 05:05

Wow, What does all this mean ?
Col

#5 Andrea B.

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Posted 31 March 2014 - 01:18

I've taken the 3 Visible, Infrared and Ultraviolet images, dragged them onto 3 layers in Photoshop, aligned them and then assigned each layer to a different RGB colour channel to make a new composite, "multi-spectral" image. You get a different look depending on which image you assign to which channel.

For the 3rd image above, I used Orange, Green-Blue and Purple channels instead of the basic Red, Green and Blue channels.

Typically the layer alignment step will only need very minor nudging with using a lens such as the Asahi UAT, but I bumped the camera rig when I was shooting the IR frame! This is slightly evident in the 3rd image above where I couldn't quite realign things in Photoshop.

In the case of this particular oil painting, I didn't find the multi-spectral composites particularly compelling. Landscapes usually give more interesting channel stacks in my experience.

In some channel stacks I made from UV, Vis, and IR gourd photographs, I was very pleased with the results because they do seem to present a 'flavor' of each wavelength in the composite result.
See this Link: http://www.ultraviol...namental-gourd/
Andrea G. Blum
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#6 colinbm

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Posted 31 March 2014 - 02:10

Thanks Andrea
I need to digest this a bit more.
I can't find anything about UAT please ?
Col

#7 Andrea B.

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Posted 31 March 2014 - 05:59

Ultra-Achromatic-Takumar
No focus shift across UV-Vis-IR.
Although I'm not sure of the precise nm range over which that holds true.
Andrea G. Blum
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#8 colinbm

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Posted 31 March 2014 - 07:00

Thanks very much Andrea
Col

#9 Bill De Jager

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Posted 08 April 2014 - 04:25

Very hard to find, BTW. I'd had a standing search for the lens on eBay with no meaningful results for the several years it's been up.

#10 Andrea B.

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Posted 08 April 2014 - 14:07

Keep an eye also on Westlicht Photographica Auctions. That is where a lot of collectible items pop up.
Andrea G. Blum
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#11 nfoto

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Posted 08 April 2014 - 15:21

At a stiff price, if I may say so.