Double Exposure

[samdring]

Party the other day and a friend sent me an image from her digital P&S which clearly showed 2 people who were transparent and were only apparent where the background was uncluttered. The rest of the image was much as she expected.
Just in case anyone thinks I am in tune with the back of beyond, these 2 people were AT the party but NOT in the shot in question.
Can anyone explain how this can happen please?

[Asher Kelman]

Some few cameras have this function. Check the early Kodak DSLR's and I think that a Nikon may do this too. Perhaps I saw this in a recent Nikon or Fuji?

I've seen this as a function discussed either here in OPF(or in the RG forum in the past 3 years). Here's one article for doing it in Photoshop here !

Although one can do it in PS, one should be able to do it in the camera!

Asher

[samdring]

Asher
You missed my point. This was not intentional. See image with child on extreme left and man three quarters right behind the grey-haired main subject. Both subjects are transparent and, I repeat, whatever happended was accidental but how?

[StuartRae]

Sam,

Forget camera tricks and PhotoShop manipulations. Your friend has obviously stumbled across a rent in the space-time continuum.

There's only one person who can throw any light on this.....................

Stuart

[Joel Slack]

Looks like it's probably a function of a slow shutter speed (low light) and people moving, but the effect is interesting. One of the most interesting shots I ever took was with a P & S, a guy was throwing something off the fantail of our ship and the flash engaged at the end of a longer exposure, which froze the action at one point in time, while allowing the blur of movement from milliseconds earlier, and the effect was dramatic. And purely accidental. Now I try to recreate that happy accident!

[Ivan Garcia]

This is a flash ghost, it happens when the flash fires and the shutter speed is very low, your friend was probably shooting in AV priority, the camera fired the flash but kept the shutter open to register the background, the boy was there when the flash fired, but moved away while the camera carried on with the exposure, so the background shows through. I have achieved this effect purposely countless times as my kids love the ghost effect for their blogs.

[Nikolai Sklobovsky]

<Total OT>
I apologize for the OT, but this post brought some memories...
1972, USSR, no such thing as a personal computer or digital camera has been even heard of...
I'm kid on the summer trip with my parents, in a place which used to be an exile home for a great XVIII century Russian poet Alexander Pushkin.
I used my trusted Smena 8-M, sort of a very basic rangefinder, and a slowspeed bw film.

The trip is over, the film has been developed (in the bathroom:-), it's the night time, the blankets have been put over the windows and door, and the magic of enlargement/developing/fixing prints begins....

... Another frame comes in, it's a picture of one of the gardens. Exposure time has been pretty much zeroed in by the time, quick framinng adjustment, the sheet goes into the developer...

The weak red light enables me and my dad to see what seems to be an impossibility: in the middle of the print a ghost picture of the poet's face becomes clearly visible..

We check the negative - no such thing..
We make another print - just the garden shot..
We're shocked - how on Earth could this happen?
....

OK, I'll keep you guys intrigued for a while and will tell your the answer later;-)
</Total OT>

[Sean DeMerchant]

Originally Posted by samdring

Asher
You missed my point. This was not intentional. See image with child on extreme left and man three quarters right behind the grey-haired main subject. Both subjects are transparent and, I repeat, whatever happended was accidental but how?

The camera was likely in slow flash sync mode or something similar (I think this is the Nikon term). The technique is called dragging the shutter. Here the "ghosts in the background" were walking through the frame when the flash fired but not during the lengthy exposure so they only appear clearly in darker areas as they were captured by only part of the light for the exposure. Techniques like this can be used with a strobing light to capture multiple images of a tennis ball on a single 1/30 exposure. But my favorite aspect of dragging the shutter is that it brings up the ambient tones of a local and often adds warmth to an image.

enjoy your day,

Sean

[samdring]

Thankyou for the replies - very useful although I suspect Stuart was the nearest to the truth!

[Chris Hindle]

Nikolai, best guess ??
Paper was pre-exposed.
Back in the early 80's I had a couple of sheets with bar patterns (which I did not put there). I called up Kodak with the batch number, and they said some QC test prints had gotten mixed up in that batch. Sent me a repacement box of paper. I think in the original box of 50 there were 3 of these "test prints"

Chris.