Pro video blog…Produced by Philip Johnston DoP/Editor


I had to wait till my filming was done this morning before performing the Z Test on my very own Canon C300 as a dead C300 is not good news for future work prospects !

The Z Test allows me to inform you how a camera will perform under major stress during recording and one major stress is a sudden loss of power, while recording I disengaged the battery causing an immediate power failure, does the recording survive ?


1. Up to 30 seconds the recording is lost

2. From 35 seconds onwards you will get an attempt recovery warning on power up, you say “YES” and it then tells you to check the file. You will retain all but 8-10 seconds from the end of the recording which is very useful to know.

3. As a further test I recorded 5mins of footage and the last 7 seconds were missing.


This all depends on the cameras ability to recover the file but interestingly it takes the same time (seconds) to recover 40 seconds as it does 5 minutes.

At least we now know after 30 seconds your footage is written to card and all the information is recovered apart from the last 10 seconds, this should stop you having a major panic in the event of complete power loss.


Having been working in the video business since 1988 I have amassed a great amount of knowledge of both the kit and production values over the last 30 years.

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