Video cameras and dSLRs: Shutters?

[Adey]

Ok ive been wondering about this a while now and have finally remembered whilst being near a pc

When a dSLR records video, the shutter is always open, as it is with live view aswell i'd presume. So then what happens with shutter speeds? Does the shutter close itself and then quickly re-open for the exposure time or what?
Or is it simulated by the sensor turning on and off? And if so then why do we need shutters at all, besides dust issues?

And what does a digital film camera do, does it have a shutter - either mechanical or circuit based?

The thing that finally tipped my curiosity was reading about someone using a dSLR for filming, and shutter speeds (40th/sec) being mentioned.

Can you folks enlighten me please

 

[Markk]

Ok ive been wondering about this a while now and have finally remembered whilst being near a pc

When a dSLR records video, the shutter is always open, as it is with live view aswell i'd presume. So then what happens with shutter speeds? Does the shutter close itself and then quickly re-open for the exposure time or what?
Or is it simulated by the sensor turning on and off? And if so then why do we need shutters at all, besides dust issues?

And what does a digital film camera do, does it have a shutter - either mechanical or circuit based?

The thing that finally tipped my curiosity was reading about someone using a dSLR for filming, and shutter speeds (40th/sec) being mentioned.

Can you folks enlighten me please

Not too sure if I can help, but I seem to hear the following on my D90 when taking pictures while using liveview.
Click - to open live view
Press silver button to take picture
Click - shutter closes
click - shutter opens
click - shutter closes
click - shutter opens to get back into live view

As for filming, I think that shutter speed is mentioned simply as the last shutter speed used before starting filming but it doesn't affect the movie. Whereas aperture and exposure do most of the work.

 

[jomike]

In video mode, a DSLR's shutter is electronic. (sensor turns on and off).

Some older low end Nikons, D40 and D50, were electronic shutter over a given shutter speed, because the mechanical shutter was not fast enough. The down side was that you got blooming on bright light sources, the up side was a 1/500s max flash synch.

Most DSLRs now use purely mechanical shutters. P&S use electronic AFAIK.

Digital video cameras use electronic shutters, at least the lower end ones do, and they also suffer from blooming.

 

[Adey]

Thanks for the info guys. Since getting into photography i've been really curious about how film cameras work. Someone the other day mentioned his wife being a focus puller, didnt know what it was , but an hour later i knew stuff i didnt know before

Cheers like!