The most obvious difference is the pixel resolution: The original Phantom Flex (aka Flex 2K), has a 2.5K sensor and the Flex4K has a full 4K sensor.   There are many other differences, which we have tried to capture here:

Recording media

The Flex (2K) uses the CineMag or CineMag II non-volatile magazines. These are available in 144, 256 and 512GB sizes, and mount to the top of the camera using a pogo-pin array (also referred to as the ‘magmate’ board).

The Flex4K uses a new CineMag design, called the Phantom CineMag IV. The CineMag IV is available in 1TB and 2TB memory sizes. They mount in the side camera enclosure of the Flex4K, and are not compatible with the earlier cameras.

In both cases, Raw Cine files are transferred from RAM (or recorded directly) at speeds over 800 Mpx/second. The Flex4K will also support compressed recording to the CineMag IV in early 2014.

Image properties

The Flex (2K) has a maximum resolution of 2560 x 1600 on a super 35mm CMOS sensor. The pixel size is 10 microns. The Flex4K is also super-35mm but with a full resolution of 4096 x 2304 and with  6.75 micron pixels.

The dynamic range is higher, and the overall noise level of the Flex4K is significantly lower than the Flex (2K).

The base sensitivity of the Flex4K is ISO 250T, and the exposure index can extend the image up to over 1000 (ISO equivalent) without significant loss of image quality. The Flex (2K) has a base sensitivity of ISO 1000T, but we don’t recommend pushing the exposure index on that camera in order to maintain the optimum image quality.

Another difference is that the Flex4K has a progressive scan shutter (with less than 1ms scan time), and the Flex (2K) has a global shutter.

Regarding color processing, the Flex4K operates from the newer Phantom protocol, which lets you set the white balance in degrees Kelvin as opposed to RGB gains like previous Phantom cameras.  Powerful image processing controls like tone curves and color matrix are also possible with the Flex4K.

On-camera controls

The Flex (2K) has basic controls on the left side of the camera. The camera needs to be connected to a viewfinder or monitor to see the menu and settings change.

The Flex4K has similar controls on the left side, but on the right side there is a new full menu system that lets you control every setup and control parameter of the camera, including user settable buttons that let you adjust your favorite settings quickly.  This full menu is displayed on a built-in LCD menu.

Power & battery control

The Flex (2K) has two 24-volt power inputs. One can be used as the main AC power (220 watt power supply), and the other can be connected to a stand battery to use as a battery backup. OR, power the camera with a stand battery (like the Anton Bauer VCLX series)

The Flex4K has one 24-volt power input, and the option for one built-in battery back to accommodate either 24v Hawk Woods batteries or 2x 12V Anton Bauer batteries. More info about the battery types and specs are coming soon.

Video features

The Flex (2K) has two 1.5G HD-SDI outputs and one component video signal, and they all output an identical scaled 1080p or 720p output.  The two outputs can work together to provide a 4:4:4 1080p signal.

Each of the Flex4K’s 4x main HDSDI outputs can switch between 3G and 1.5G, and two of them can be used together for a dual-link 4K signal.  The camera can be set to continuously monitor the live feed where 2 of the outputs play back what was captured to camera RAM or the CineMag IV. Also, the Monitor/VF and Record outputs can be independently switched between Rec709 and 2x pre-defined Log modes.