ARRI ALEXA Mini & Gates MINI Housing – Initial Field Tests
by John Ellerbrock
Bob Cranston and I spent the weekend of July 11/12 diving Catalina Island with the new ALEXA Mini camera and Gates MINI housing. This is a fun part of my job: testing all the new underwater rigs. J What follows are my comments and opinion about the housing and camera performance.
READ THIS BEFORE WATCHING THE VIDEO
This was a challenging shoot, for two reasons:
- Firmware. First, the prototype Mini camera firmware was limited, and did not include a WB SET function. This is important if you’re ‘baking in’ color correction to ProRes, Mini’s native recording format.That said, I took this as an opportunity. With a preset color temp (7300), how much could I correct in post? This would give me an idea of what to expect from Mini when WB SET is actually available.
- Water conditions. Catalina waters were less than optimal. Visibility ranged 20-40 feet, with a ‘chalky’ look, acting like a soft filter to the some images which lack that ‘tack sharp’ look.
Notes about the cut:
- What not to do. You’ll see on-screen highlights of two rookie mistakes I made while adjusting to the new rig. The second Bat Ray clip has an overexposed / clipped corner, which I could do nothing with in post. The Tube Anemone clip illustrates soft corners, the result of shooting the Sony 11-16 lens at full open iris. This is classic behavior of rectilinear lenses.
- Split screen grading. Several clips are split screen showing before / after grading to illustrate the difference.
- Noise. The first Bat Ray clip was aggressively graded and obvious noise appeared. Something to avoid in post. (Pete Lightowler – being far more adept at grading than me -- says that DaVinci Resolve can reduce / eliminate noise with some built in tools).
- Slomo. Mini allows setting bot a Project Frame Rate *and* a Clip Frame Rate (FPS). In this case, 24 and 48, respectively. Playback straight from the camera is 1/2 speed.
Conclusions / Opinions
- Latitude. I am pleased how far I could adjust exposure and push the color grading before things fell apart. Only the Bat Ray shot generated noise, and that’s due to my severe grading. Otherwise the Mini camera / ProRes codec captured detail and color that could be teased out in post. I look forward to further testing in different conditions and a proper WB SET function. I expect easy grading and superb results.
- Magenta. Mini’s showed no sign of the dreaded magenta issue. While this is far from conclusive given the limited conditions at Catalina Island, it is encouraging. Testing in tropical waters will be more revealing.
- Gates MINI Housing. While accolades of the MINI housing will appear totally biased, I’m actually a harsh critic. Here at Gates our job is to find and correct issues before product launch. So to say that the MINI housing is one of the best Gates has ever produced is indeed high praise. It has all the classic elements you’ve come to expect (bulletproof, precision ports, broad lens support, extensive accessories) but adds new features like 12 assignable buttons and a new, compact external monitor housing for the Transvideo Starlite.
Camera / Housing Setup
- Canon 15.5-47. This is amongst my favorite lenses. It is usable through the entire zoom range with the SP80-8 (8 inch) Dome Port.
- Sony SCL-P11x15 11-16mm. This is a repackaged Tokina 11-16, a reasonably good rectilinear lens option. At T3.0 (wide open iris) the corners are soft, so it’s necessary to stop down
- Camera settings.
- FPS 48. Project frame rate 24. (Playback is 1/2 speed).
- Shutter 1/60.
- Exposure Index 800 (chosen to look for noise in low light conditions).
- ProRes 422 or 422HQ (this was necessary for reasonable recording time underwater, which was 9 minutes at these settings)
- Post Processing. Grass Valley Edius and Final Cut Pro.
Watch in 4K: