A7s Grading with Davinci Resolve / by Matt Mahoney

I had the opportunity at the studio today to test a BlackMagic Design URSA. The original idea was to put the URSA through a series of tests to see how and when the image would break during a lighting test of the over and under exposure. These tests take a long time though, more time than I had today which is a bummer. What I did do was briefly test it against the Sony A7s. I shot a wide, a MCU, and CU of a guy I work with in a simple lighting set up. I wanted to see if they would match, or if I could even get remotely close in the grade.

This is a simple camera match grade. I used 3 different lenses, the Zeiss 50mm 2.8, 85mm 2.8, and 135mm 2.8. This glass is really good and I've done my best to get them from the same batch. But due to the age of these lenses combined with the fact that they probably aren't of a similar manufacturing run, the glass isn't quite matched in color and contrast.

This is why a grade test was worth the effort. These 3 lenses are relatively closely matched, but do have their differences, which I knew about but haven't fully tested the entire set yet. I set up a basic interview lighting scenario and dialed in the three focal lengths. 

This test isn't very scientific. I didn't use a color chart or a grey card, just a light meter to get exposure of the face (f/5.6), iris change to get a +2 stop exposure to deal with the SLOG2 (f/2.8), and some grading to match them all. I highly recommend you test the hell out of your gear. You find all sorts of things that you can keep in the back of your mind (or written down if you're like me) so that when you're on a job you know how your camera/lens combo is going to handle different situations.

If I had my low watt bulbs with me I would have swapped out the bulb in the practical fixture back in the corner frame left. But whatever. I'll go into my experience with matching the URSA and the A7s footage soon. In the meantime I've almost dialed in a custom starting correction LUT that knocks down the annoying +2 stop over exposure needed to get the most out of the SLOG, along with curve and sat nodes so you can see what the hell you're lighting with this camera. Hopefully this will come in handy once I pick up the Shogun. If anyone's interested, I can share once I know it's working well.