DSLR Video time limit

I've tried to research how the video time limit is implemented on the D90 and 5DMkII, can't seem to get a clear answer.

Is each clip limited to 5min on the D90 and 12min on the 5D, or is that the total time for all clips on the card, and is this irrespective of card size? How is that time limit 'reset', turning on and off, changing the card, waiting a certain period of time?

I've tried to research how the video time limit is implemented on the D90 and 5DMkII, can't seem to get a clear answer.

Is each clip limited to 5min on the D90 and 12min on the 5D, or is that the total time for all clips on the card, and is this irrespective of card size? How is that time limit 'reset', turning on and off, changing the card, waiting a certain period of time?

Can only speak for the 5d, but the clip is limited to 4GB (well in practice it has been 3.99).

In HD this gives you +/- 12 mins. UW it will be longer... I got 14min 29sec... as the compression seems to act a bit like jpeg, in that if you are shooting all one colour (blue UW) and low contract the compressed file will be smaller than if you are shooting a big range of colours+ tones.

In SD the 4GB clip length will be longer as it's lower res +/- 24 mins.

That is each clip... button on to button off. So it's not really an issue most of the time, as in reality unless you are doing some specialised shooting (maybe some behavioural activity longer then 12-14 mins) you just button off and button back on again to start a new clip.

Can only speak for the 5d, but the clip is limited to 4GB (well in practice it has been 3.99).

In HD this gives you +/- 12 mins. UW it will be longer... I got 14min 29sec... as the compression seems to act a bit like jpeg, in that if you are shooting all one colour (blue UW) and low contract the compressed file will be smaller than if you are shooting a big range of colours+ tones.

In SD the 4GB clip length will be longer as it's lower res +/- 24 mins.

 

That is each clip... button on to button off. So it's not really an issue most of the time, as in reality unless you are doing some specialised shooting (maybe some behavioural activity longer then 12-14 mins) you just button off and button back on again to start a new clip.

OK, so it's really no big deal, even on the D90, and the amount of video is limited only by the size of the card. I read somewhere that on the D90 5 min clips range from 800MB to 2GB max. As the reason for this limit supposedly has to do with the sensor overheating, are there any recommendations for how long to wait between clips?

In the manual of the D90, it states that once you hit 2GB or 5 mins in 720P, it stops recording. The manual states the heat from the sensor causes banding and other noise and color artifacts to show up. My 1 hr test of the D90, I shot 3 continuous clips and the camera shut down by the over heat protection system. It gave me 30 seconds of warning like a MI bomb. I'm guessing it'll allow you to shoot when the temperature cools down and repeat if it heats up again.

5D2 is different. The FAT32 flie system limits file size to 4gb. So once it hits 4GB on the last I frame of the GOP, it stops. I think the Digic IV isn't fast enough to convert the buffer to do a continuous recording onto a 2nd file.