ALEXA XT Open Gate
Record it all: Open Gate sensor mode
A recording mode using the full sensor area has been made possible through the increased processing power of ALEXA XT cameras. While 16:9 and 4:3 modes will remain the standard for most ALEXA capture, some specific situations will benefit greatly from recording in Open Gate mode, including wide establishing shots, image repositioning, resizing, rotating or stabilizing, native 3.4K VFX work, or up-scaling to 4K.
ALEXA XT cameras are able to switch from recording normal ARRIRAW to record the entire active image area of 3414 x 2198 photosites, yielding a 1.55:1 'Open Gate' image with slightly shallower depth of field and no surround view. Lenses must cover an image circle of 33.5 mm, so it is important to test — especially with wide angle lenses — to make sure that they cover the entire image area. Most spherical prime lenses above 20 mm are suitable, as are spherical zoom lenses at the longer end of their range.
Bill Bennett, ASC, was the first to test the feature, commenting: "When we viewed the results up-rezzed to 4K, we were surprised at how good 3.4K looks. However, my clients don't want to process or distribute in 4K; they all love how the ALEXA looks. What they want is a little more resolution from the camera for repositioning, resizing, stabilizing or rotating the image. The Open Gate mode provides exactly that."
When shown test footage of the Open Gate mode, Oscar®-winning VFX supervisor Rob Legato thought it to be "a significant increase in sharpness. This could be used to reframe a 2.8K window inside the 3.4K acquisition, to work natively in 3.4K for VFX or to render the 3.4K to 4K and zoom in as required. Either way, it is a significant new option."