I've done lots of 1/2 second exposures with 3s interval, and it shoots some at much shorter interval than 3 and some 3+??? At one point, the docs said 5s was a barrier. Maybe it was the 5dmkii specifically. All of my cards are rated higher than the 5D can write (but makes DIT much faster) so I doubt it is write speed interfering. What makes me think it is not the camera is that using a cheap external timer works without skipping a beat.
I've done lots of 1/2 second exposures with 3s interval, and it shoots some at much shorter interval than 3 and some 3+??? At one point, the docs said 5s was a barrier. Maybe it was the 5dmkii specifically. All of my cards are rated higher than the 5D can write (but makes DIT much faster) so I doubt it is write speed interfering. What makes me think it is not the camera is that using a cheap external timer works without skipping a beat.