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Sony NEX-5N (monochrome) for UV/IR

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#41 nfoto

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Posted 10 May 2020 - 18:28

Yesterday.

#42 dabateman

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Posted 10 May 2020 - 21:03

Wow excellent harsh photo.
The details even here are excellent, after the website software touches it.

Glad your back out moving around.

#43 nfoto

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Posted 10 May 2020 - 21:44

Moving around with extreme care and using a mask if need be. The "social distancing" aspect is easier to implement in my neck of the woods.

However, doing photography with a mask over your face is not my favourite approach :sad:

#44 Andrea B.

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Posted 13 May 2020 - 16:28

I enjoyed so much my walk with Ruth along the River Glåma. It was beautiful. And I found many wildflowers along the way.
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#45 nfoto

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Posted 19 May 2020 - 18:46

The NEX-5N is good for IR. One gets almost a "genuine" Kodak HIE feeling about the images produced.

Attached Image: S202005190817_World_of_HIE_830IR_25CVf4_NEX-5NMonochrome.jpg

Am example from today, a snapshot from my porch with the 25mm f/4 Voigtländer Skopar SC and the B+W 093 filter.

#46 Andrea B.

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Posted 20 May 2020 - 16:02

I like the boat on the lake of white grass.
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#47 nfoto

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Posted 06 January 2021 - 12:42

Same view, but now in wintertime. We had a very long and wet "pseudo-winter" so far, but last week snow arrived and with it, the cold so typical of a Nordic winter. Today it is -17C and I don't envy the young lady walking her dog. On a tangential note, I snapped the photo because of the dog as we have a saying here of "bikkjekaldt" which is the exact opposite of the English "hot dog".

Handheld at ISO 1600, 1/30 sec, if memory serves, f/8, using the W-Nikkor 3.5cm f/3.5 rangefinder lens for the late '50s on the NEX-5N.

Attached Image: S202101060954.jpg

Despite my hands shaking in the biting cold, the image came out with a pleasant crispness. This Nikkor is not amongst those old lenses transmitting UV into the very "deep" range, but obviously it suffices to give a nice UV snapshot. What more can one wish for (except for less cold weather) ?

#48 Andrea B.

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Posted 07 January 2021 - 22:09

I don't think I would know this is a UV photo if you had not told us. :grin:
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#49 Stefano

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Posted 07 January 2021 - 22:23

UV appears very similar to visible when in B&W.

#50 nfoto

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Posted 08 January 2021 - 06:01

There are tell-tale signs. For example, the very visible frost patterns on the housing walls. These are not visible to the naked eye.

#51 Andy Perrin

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Posted 08 January 2021 - 06:22

Could we see a B&W visible photo of the same scene? I don’t see the frost patterns but I’m probably not looking at the right thing.

#52 nfoto

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Posted 08 January 2021 - 07:55

Look at the houses left and right. See the criss-crossing pattern on the facades? That is caused by heat transfer through the wall support structure.

The visible impression of the dwellings is pretty much like what you can see in the previous IR picture (sans the IR "glow" of vegetation, of course).

#53 Andy Perrin

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Posted 08 January 2021 - 15:39

I see some horizontal lines on the houses that might be what you are referring to? They remind me of what I see with the thermal camera.

#54 nfoto

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Posted 08 January 2021 - 17:07

Yes. Those are the tell-tale signs of thermal transfer, which of course with an ambient temperature around -17C will generate frost patterns.

The actual house paint colours are different (white-cream-greyish blue), but of course not manifested as such in monochrome. However, as UV "sees" the pigments most facades are UV "blue" due to TiO2 and other pigments, so are rendered quite bright in monochrome UV no matter what visible colour they represent.

#55 Andy Perrin

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Posted 08 January 2021 - 19:12

TiO2 is a strong UV absorber (hence its use in sunscreens), so I'm not sure why it would be UV bright on houses. It could be responsible for the blue I guess by absorbing, but it would not act to brighten the reflectance, very much the opposite.

#56 nfoto

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Posted 08 January 2021 - 22:03

Well, the house colours are white, pale cream, or grey blue, (one even brown, but not visible on all photos), and all look light grey in UV (monochrome).

#57 Stefano

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Posted 08 January 2021 - 22:18

It may depend on how deep you are imaging in UV. UV-blue indicates increasing absorption at shorter wavelengths, and so such objects/surfaces appear lighter in the upper UV.

#58 JMC

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Posted 08 January 2021 - 22:33

With TiO2 how it appears in UV depends on particle size and wavelength. Larger particles tend to scatter more UV, while smaller ones absorb more of it. I seem to recall as particle size decreases, the transition between scattering and absorption moves to shorter wavelengths, but would need to double check that.
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#59 Andy Perrin

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Posted 08 January 2021 - 22:34

Stefano, TiO2 is very strongly absorbing in UVA. While the exact spectrum depends on how it's annealed, typical curves look like this. 3.1eV = 400nm, 3.3eV = 375nm.
Attached Image: Screen Shot 2021-01-08 at 5.31.41 PM.png

Jonathan, good point about the scattering. I'm sure that must be why it's so light looking. The situation is analogous to the snow in my NIR/SWIR photos -- when the absorption coefficient was in the moderate range in the NIR pics (980nm), the snow appeared light due to scattering dominating, but as you push towards 1450nm, it went black eventually.

Edited by Andy Perrin, 08 January 2021 - 22:40.


#60 nfoto

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Posted 17 January 2021 - 14:16

Plenty of snow combined with bitter cold (down towards -20C) and recent health issues keep me indoors these days. Still one can manage a comparison of UV vs visible scene rendition, even shooting through triple-layer glazing. The monochrome version of the NEX-5N (courtesy Vivek Iyer) allows for hand-held UV although the outdoor scenery is a darkish white-out of frost fog and snow.

Taken with the 3.5cm f/3.5 W-Nikkor (RF mount) on the NEX-5N, shooting through a triple-layer window that robs a lot of the image sharpness. UV needs about 6EV more exposure and alters scene reflectivity only in subtle manner for this winter scene.

Attached Image: WNikkor3,5cmf3,5_UV_vs.Vis_NEX-5NMonochrome.jpg