Weird effect

[jaapv]

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Can anybody explain these weird blue highlights:confused: I havent seen it before in 13000 shots...It was just an exposure test shot before my wife's birthday meal, and none of the other shots showed this. ISO 640 EV-1. (not the right exposure anyway )(No IR filter too, that curtain is mint-coloured..)

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[SJP]

light from outside reflected on the silverware (chrome ?) & wine glasses, see also on the windowstill - same color

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[Hans Roggen]

light from outside reflected on the silverware (chrome ?) & wine glasses, see also on the windowstill - same color

 

That would be my guess too. Did you change the white balance after this testshot? Or did it get dark soon after this shot? That would explain why the blue highlights didn't show in the rest of the shots.

 

En nog gefeliciteerd Jaap.

[jaapv]

Nope- No blue neon lights in my garden or room, no UFO's hovering. All other shots had no hint of this. The reflections are too pure blue and cyan to be real too... Thanks Hans:)

[gwelland]

It almost looks like the highlights clipped and were recovered but lost red/green. I could understand it in post-processing or with a raw converter but not directly from the camera like that.

 

I also wondered if there were some other illumination sources outside the visible spectrum but that the sensor is sensitive to? I know the classic example of this is the colour shift we see with things like Blue Bells.

[Hans Roggen]

If your white balance was set to tungsten you'd get these kinds of blues from what's left of daylight outside.

[jaapv]

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AWB, this was a dng anyway C4 settings "as shot" It was well underexposed; I pulled it up 1 1/2 stops.

[badpets]

sometimes natural light in the evening from outside can appear quite blue in the images. this image doesnt look extremely weird though. does it happen to other photos under similar condition?

[luigi bertolotti]

Is almost incredible... you say, no PP, directly on the developed DNG you already got this weird blues ? For me, the most interesting is the dish in 2nd plane... i suppose is dark blue, and only half or so is heavily "tinted"... something which makes one think at effect related strictly to specific angle of reflection of SOME lightsource... but WHICH one ? Was there some other light besides the candles ?

[luigi bertolotti]

AWB, this was a dng anyway C4 settings "as shot" It was well underexposed; I pulled it up 1 1/2 stops.

 

Were the blue/cyan markings visible also before pulling up the exp ? The "clipping" therory, for me, is the most probable...

[jaapv]

The dishes are black, any other light is tungsten.As you can see through the window, the light in the garden was very low, and not blue.

[jaapv]

Were the blue/cyan markings visible also before pulling up the exp ? The "clipping" therory, for me, is the most probable...

Immediately, on the camera LCD.and straight away in C4.

[Hans Roggen]

I know light from outside is not blue, but it can appear quite blue, in fact, as blue as in your picture if your white balance was set (by you or the camera) to tungsten.There was probably just enough left to appear like this in your test shot and gone by the time you were having dinner.

[jaapv]

I hear what you are saying, Hans, and I thought of that too, but none of the other shots before and after show the same effect. It must have been a very short flash in that case. There is horizontal banding in the window too.

[gravastar]

There are several things that are curious about the blue artifacts.

 

They only seem to appear on specular reflections from horizontal surfaces. That would tend to support the theory it's blue skylight from outside the window. Reflections from near objects facing away from the window like the inside rim of the wine cooler, bottle and inside of the dark dish are normal.

 

The effect certainly looks like channel clipping and this would be supported by the appearance of a vertical blue highlight halfway down the stem of the nearest candle. The stem's lensing effect increasing the intensity of the light reflected from the knife. However you would expect the naked candle flames to show the same effect - unless their color temperature was very low. Hmmm... thinking about this the candle could be as low as 1500K and the outside skylight 15-20,000K. Since the overall color balance of the picture is only slightly warm and matches the candlelight the blue channel must have had a very large boost.

 

I suspect the effect can be explained by the blue channel clipping due to the very large color temperature difference between the ambient room light and low intensity residual skylight. I'm always suprised how the eye/brain ignores such large differences. For example blue LEDs shining on a wall lit by tungstem room light, the color difference isn't that noticeable until you take a photograph!

 

ETA: If you look carefully at the inside edge of the wine cooler the specular relections are normal except for a small blue spot at the very left where light from the window is reflected.

 

Bob.

[Hans Roggen]

Just took this otherwise crappy picture in my son's room with the blinds closed to keep most of the daylight out (to simulate the evening). Looks like the effect in your picture to me. I put the cd in to reflect the light from outside like on your plates, cutlery and window sill. Maybe it was a cloudy night with a little piece of blue skies between the clouds?

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[antonv]

Have you thought about a police car with flashing blue light driving by the very moment you pressed the shutter?

[jaapv]

Have you thought about a police car with flashing blue light driving by the very moment you pressed the shutter?

I've never had that in my garden! I certainly would have noticed:eek:

[Dantist]

Typical "before dinner or sunset" colored skylight, close to UV range, reflected from the same source.

The sensor might be over eye-ranged, may be that's why UV/IR filters are provided ?

Beautiful colors anyway, I will have to try it soon, over the polar circle

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[luigi bertolotti]

Jaap... my impression & advice : "strange things do someone happen in this world...forget it and go on..."

 

(the cd posted by Hans is significant... strong random reflections by silver/glass surfaces...)