This is a slightly technical post. I don’t imagine many people will be interested in it, so just ignore it. But someone somewhere might find these findings useful. I sure learned a lot from doing these.
For the Short Film we’re doing centered around the New York Police Officer, wanted to do it as high caliber as possible.
Filming at night so chose the Canon 5D MKIII with Magic Lantern to allow us to film on RAW.
Got two 64GB UDMA cards from Amazon. Komputerbay cards. Doing a little search on the internet you’ll find posts upon posts about the Komputerbay cards. So to summarize all these posts.
1. They’re almost exactly the same as Lexar cards but much cheaper, it’s just a bit of a gamble if they’re going to be good or not.
2. 64GB is supposed to be the most efficient. (Hence buying 2, instead of one 128GB)
At 1080p RAW, 24fps.
One card averaged a 90MB/s write speed.
The other a not so good 60MB/s write speed.
I tested the cards filming at 1080p RAW. First card was fine. The second card dropped A LOT of frames and generally I got a few errors from it.
Also, quite an important note. Filming at 1080p RAW did seem to take up about 4.8GB PER MINUTE.
So I dropped the resolution to 960p and I still had issues with the second card. Dropped to 900p and both were fine.
Here’s some useful info I put together showing what write speed you need filming at different resolutions.
This is 24fps
1920 x 1080 - You need a write speed of at least - 83MB/s
1800 x 960 - 73MB/s
1600 x 900 - 57MB/s
1280 x 720 - 37MB/s
1120 x 580 - 26MB/s
Also, the lower down the table you go the less data it takes up.
Did a quick test for this and found 900p takes up about 3.2GB per minute. Which is still a lot less than the 4.8GB per minute (1080p RAW).
Shoot time per card (64GB)
1080p RAW 24fps - 13 minutes.
900p RAW 24fos - 20 minutes.
So basically what I learned from this short test was that I’m probably better off shooting at 900p and upscaling my footage to 1080p or alternatively, send the slower card back to Amazon for a replacement and just hope for good luck that the card’s better.