1/12 shutter speed at 25fps?

[mpalomaki]

Hi,

I have a PAL camera and I can set the shutter speed to 1/12 at 25fps. Does this make sense? Can anyone explain how this works?

Kind regards,
Mack Palomaki
Singapore

[jwfilm]

I am also very curious to hear an answer to this enigma.
Barry mentioned in some other thread that you loose resolution when you use a shutter speed lower than your framerate. He explained how it worked, but I didn't comprehend.
All I know is that you actually get more light with 1/12 shutter speed...it's a push-button miracle.

[mpalomaki]

What really makes me think about this is that 1/12 sec is not an exact multiple of 25fps...

[Barry_Green]

You lose (vertical) resolution in an interlaced camera if you set the shutter speed slower than the capture rate. i.e., if you use a Sony VX2000 at 1/30 shutter speed, it has to drop to a single field instead of two fields.

On a progressive camera you don't lose (vertical) resolution, but you do lose frames (temporal resolution). If you set the shutter to 1/12, you'll get 12 distinct frames per second. It'll still record the 25 frames per second, but each one will be duplicated.

1/12 shutter on the PAl camera is 1/12.500 of a second, so it is an exact multiple of 25fps, just the display is rounded down.