Arri recently released version 9 of the Alexa Firmware. Part of this update, for Alexa XT cameras, is a feature called Open Gate. Open Gate uses the full resolution of the sensor, including the space reserved for look around to generate a 3414×2198 resolution ArriRaw image meant to be up scaled to 4k. One of the issues with Open Gate, is that Arri’s Frame line generator web app. is not capable of generating frame lines for the new sensor mode. Included in the White Paper for Open Gate is a work around to generate frame lines. It’s nice of Arri to offer a work around, but the really cool thing about it is the other use of the work around. It has been an issue on any production that has to jump back and forth from 4:3 to 16:9 sensor modes with the extra steps in re-loading custom frame lines. Custom frame lines don’t get automatically recall with a user setup. The issue is that a custom frame line is loaded from the SD card and temporarily stored in the cameras memory. Switching sensor modes factory resets the menu, clearing your frame line.
The work around from Arri uses the user rectangle feature to draw the frame line. User rectangles are recalled with user setups. Here are the step by step instructions on how to recreate an accurate frame line using user rectangles as written by Arri. (To test the process I started with the web tool to create a PNG image file, opened it in Photoshop, modified the frame size, and save my .JPEG)
Create a JPEG with a resolution of 3414×2198 pixels with the required rectangles/objects (see sample image OpenGateMarkers.jpg) and save it to an Alexa formatted SD card in folder ARRI\ALEXA\Grabs\. Note: you can also do this with other formats, such as:
2048×1536 for 4:3 2K, 2048×1152 for 16:9 2K or 1920×1080 for 16:9 HD
On the camera (using the matching Sensor mode respectively recording resolution) set MENU > FRAME GRABS > COMPARE GRAB 2 LIVE IMAGE > OPTIONS > COMPARE MODE = TOGGLE. Load the JPEG image you created with LOAD GRAB and select COMPARE.
On the viewfinder press [EVF] to open the EVF submenu. Set USER RECTANGLES to RECT 1, RECT 1 or RECT 1&2 depending on the number of “boxes” you need. Then go to EDIT USER RECTANGLES and adjust the top, bottom, left and right red lines to match your required rectangles/objects observing the EVF or MON OUT of the camera.