Thursday, 20 December 2007

Richmond Bridge, night, cold, calm - # 328

A "less often seen" night-time view of the bridge (built 1778). Often the river is surging through the arches but this time, calm weather and probably "slack water" at the turn of the tide, it is as calm as a mill pond.
About a week ago Richard at http://zurich.dailyphoto.forthmedia.com/dailyphoto/index.cfm posted a fine photo of Venice at night in which the street lamps displayed a simple and very attractive star effect. Here we also have a pleasing star burst inside a very distinct hallow bubble. Is this the effect of the camera lens, or the lens covering on the lanterns? Is it an accident, or is it the result of careful research by lighting engineers for the benefit of car drivers?

11 comments:

  1. I'm have now answers to your technical questions... can only see a nice bridge on a nice photo!

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  2. Me, I can't explain it technically eihter, but it really looks nice, especially in b/w which underlines the architecture of the bridge, the soft lines of the arches.

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  3. Here how I understand it, but I haven't worked it out on paper yet myself: The starburst is a result of diffraction at the edges of the blades of the aperture diaphragm. The effect becomes apparent with "point" sources when the aperture is small. The claim is that if there are an odd number (n) of blades, there will be 2n spikes; if n is even, then there will be n spikes. So, that means my Lumix FZ7 has a 6 blade diaphragm as seen in this photo here. Richard's would be 8 as he reported. Yours seems to be 7 as you have 14 points. Here are a few links:

    "Another phenomenon affected by the aperture are diffraction stars."

    (what is) The physics behind the "starburst" effect (?)

    A Flickr page with a couple of examples of different numbers of aperture blades

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  4. Ludwig Boltzmann20 December, 2007 17:12

    Hey Z, are you some kinda particule physician or what?

    Richard

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  5. At this time of year we need more hallow bubbles - sounds like some kind of space telescope combined with carol singing. Z has summarised this quite nicely. Never buy a lens with odd numbered aperture blades, ever. (They didn't tell you that on DPreview, did they)

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  6. ranoutofnames.com20 December, 2007 17:25

    I suspect this has something in common with Richards photo - ie the longish exposure time - 3 secs maybe? This helps give the glassy effect to the water and reflections

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  7. I cant explain your quandry, but I like your picture just the same!

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  8. Exactly. Lots of my photos are more luck than judgment, but I'm not complaining! I really like this one, and I think it works really well in black and white.

    Jackie
    Glasgow Daily Photo

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  9. Interesting that the lights look like florescent tubes when reflected in the water.

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  10. how was the weather that night? any moisture in the air would have helped contribute to the glow. looks maybe like you were getting errant lightrays also contributing to those hollow rings you see round every light. only oher thing i can think of is slight overexposure on the lamps
    direct flickr link
    to the flickr page/comment that describes the diffraction with examples

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