Sunday, January 30, 2011

iPhone shutter effect

The photo is found here.
Here are some weird shots from a scanning camera.

Though not really related to the moire effect mentioned in last post, I just remembered the amazing visual effect of this photo. The effect is said to be from the shutter scanning across the frame. I guess the iPhone has an electronic shutter instead of mechanical one with a moving slit going across the frame, though I'm not sure how it's relevant to the effect.

I'm wondering though if this photo is not composed from several exposures, each one having one strip of that propeller?

Alex found this video which shows just how this happens, very kewl.

1 comment:

Alex said...

But that is exactly what "rolling shutter" is.

Here's an analog example.

Take a contemporary film camera. It has two curtains to the shutter, one drops open, then a short time after the second drops closed.

Now have the shutter take 1/128th of a second to fall. Let the two shutters be started a micro second between. (don't get into all that diffusion on point source of light).

Use a very fast film. Now the shutters take many slices of photo, and composite them together.

The electonic film, the sensor does this. It samples one line of pixels at a time, and writes them out to the memory.

You have efectively taken what 1000 pictures 1 pixel by sensor width and stitched them together.