Sunday, October 24, 2010

House Urchins

Sea urchins are usually found in the sea. When beachcombers find them and transport them home, they're known as house urchins. Here are some tiny ones, about the size of a 5 cent piece.

Why are the shadows blue? Please tell me.

8 comments:

  1. Q. Why are the shadows blue? Please tell me.

    A. Possibly because the room lighting is artificial, such as tungsten household light bulbs. These have a lower colour temperature (around 3400 K), so giving a warmer illumination to object, resulting in warmer tones ... yellow / red. Our eyes will adapt to this warn tone, so objects appears normal to us. Traditional film is balanced to around 5000 K, which is close to daylight (though you could get film balanced for other light sources, but with the digital age, not sure if these are still available). Digital cameras also have a set standard colour balanced of around 5000 K (prior to any manual or auto white balancing). So with this warmer illumination, your image has recorded with warn tones, as the film or chip was balanced to expect neutrals to be cooler than illuminated, so off balancing the tone of the image. So why the blue shadow ? There must have been some additional (secondary) lighting from a cooler light source to that of the room lighting (3400 K), such as daylight or electronic flash (5500 K). This has caused a secondary less intense shadow, which is cooler (bluer) in colour tone (but closer to normal for the film or chip). Hence the ‘blue’ shadow, has captured closer to normal, while the rest of the image (illuminated with the warmer room light) has captured with warn tones.

    To recap. The ‘blue’ shadow is thrown by a more neutral light source, as far as the film or chip has been balanced. While the rest is illuminated by a warmer light. So it isn’t the ‘blue’ shadow that is blue, its the rest of the image that is warm (yellow / red).

    Try not to mix your light sources. And if the light source is warn, use a colour balancing filter to neutralise to D50, or white balance a digital camera to the light sources colour temperature.

    All this without the use of Wikipedia, finally the years of study have paid off. Unless Lewk has a totally surreal comeback (which wouldn’t surprise me, reading the rest of his blog). Probably its just martian communication rays interfering with our brains giving us distorted perceptions on the world. Wait a minute, I didn’t think like this before reading Lewk’s blog. Are we being influenced by this higher being. Has he got us in his control. Why do we continue to follow this blog. HELP.

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  2. OMG Bod, do you have a doctorate in photography ? That's a very comprehensive answer,and you were correct - there were 2 light sources: sunlight and tungsten lamp.

    I think in future to avoid colour weirdness I stick to painting and will ditch the camera !

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  3. Lewk. Don't put away your camera. Your photo’s are great, especially the sunsets. More sunsets please. And the photo where you broke your car was worth it (though your wallet may not agree).

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  4. Bod, my love,

    Be my geek and I'll be your beauty!

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  5. OMG Lady Gaga, you betrayed Lewk...

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  6. Lewk, how should we settle this, pistols at dawn ... for the love of the lady.

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  7. Oh I'm no lady, Bod.

    But you'll find out soon enough, sweetheart!

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  8. Lady Gaga I guess you're saying you're just a young girlypin?

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