Haunting image!

[GregP]

Practising techniques at twilight to produce "starburst" effects from street lights, I shot this image. Nothing remarkable, until you look more closely at a full size version, which shows a spectral image. There are no post processing or photoshop effects.
Of course, these type of shots require the combination of long exposure and narrow aperture. I guess these settings and the light conditions explain the phenomenon, though I cannot recall seeing anyone in the frame. The jpeg photo was taken from an upstairs window and the area of the shadow figure was about 25 metres away. The settings on my Nikon D3100 were as follows: ISO 400, aperture f10 (not narrow enough, really), focal length 55mm, shutter speed 4 secs.
Can anyone give me a clear (ie non-technobabble) explanation of why the transparent shadow appeared without the appearance of a solid blurred figure anywhere?

[Shadowman]

The person probably noticed your camera, stopped and reversed direction.

[GregP]

Thanks... but why is the figure near transparent?

[Shadowman]

Your slow shutter speed, if you had used an even longer shutter speed you wouldn't have captured anyone at all.

[HaseebM]

Could this be a shadow of someone?

[Donald]

Could this be a shadow of someone?

No, it is not that Haseeb. It is, as John has written, simply a result of the 4 second shutter speed that was used. At that bright spot underneath the light, the person was sufficiently lit to allow them to register on the sensor, but their movement was of a speed whereby they moved through that exact location in under 4 seconds, thereby creating the 'ghosting'.

[Manfred M]

Exactly; the person stopped long enough and stood still enough to show up in your frame. Had you shot with a faster shutter speed, the person would have looked a lot more solid. With a lower shutter speed, he / she would not have shown up at all.

[GregP]

Many thanks... case closed!

[pnodrog]

It is a pity when there is a simple technical explanation. I far prefer spooky mysteries...

[McrDave]

Hi Greg,
I went on a photoshoot at night around Manchester and the same thing works - providing the subjects stay moving, the shot looks like noone is there at all. I guess providing they don't reflect much light. Take care.

[barrydoig]

I am a lurker on this forum. I read and enjoy the conversations but I'm very busy getting old.
I think it is a person who was coming towards you when you opened the shutter. It looks like they are walking on the grass. Either that or there really are fairies in the bottom of the garden. Barry