By Matthew Jeppsen, June 24, 2008
The Brevis Flip is Cinevate’s first lens adapter system that produces images in a flipped, or right-side-up orientation. This is accomplished through the use of an internal optical array. The adapter is constructed of milled aluminum with an optical flat-black powder coating. It attaches to your camcorder’s filter threads and juts downward to a lower level imaging tube made of carbon fiber. This lower portion houses the ground glass imaging element and 35mm lens mount. The unit can be flipped over and used with the imaging tube in the upper position as well. It is powered by an internal rechargeable battery that lasts over 20 hours and recharges in less than two. The lower-level imaging tube houses an on/off toggle switch and power indicator light.
The Brevis Flip utilizes an oscillating imaging element design. This diffuse screen is the image plane of the 35mm adapter and ultimately defines the out-of-focus areas, or bokeh rendering of the final image. (The term is from the Japanese word boke — meaning “blur” — and specifically refers to the appearance of out-of-focus areas in an image produced by a camera lens.) Cinevate’s design allows users to open up the imaging tube and swap different CineFuse elements. They offer three basic levels of diffusion that progressively increase the filmic look of bokeh at the expense of greater light loss. The unit also offers a user-adjustable oscillation setting on the inside of the carbon tube. Adding and removing various still lens mounts is quick and gives shooters the option of using many different still lenses in their projects. Cinevate offers a variety of lens mount options that cover the gamut in widely available still lenses.
Collimating a lens on the adapter is an easy task with Cinevate’s micro-collimation mount design. After removing the lens mount, an internal ring can be adjusted incrementally to achieve proper focus on a backfocus chart. This collimation setting is retained across lens mount changes, so you can be assured that the distance marks on your lenses are accurate.
Cinevate states that the Brevis Flip exhibits about a half stop of light loss. With a Sony PMW-EX1 camcorder, I tested resolution and sharpness using a DSC Labs Multiburst chart. With a 50mm lens at f/4, I noted about 700x700 lines of resolution. This was with the camcorder set at an optimum zoom-in level of Z75. The Brevis Flip allows you to zoom the camera in all the way to Z99, but image detail and particularly edge sharpness suffers as you increase the camera’s focal length
. I also noted that the amount of zoom-in made a noticeable difference in chromatic aberration at the image edges. The adapter performs best at wide camcorder focal lengths.
To determine how evenly light was distributed across the frame I shot an evenly lit white background. I connected a waveform monitor to a Sony HDR-FX1 test camera and noted IRE percentage levels from left to right with various lens configurations. I found that vignetting is most apparent when the camcorder’s lens is wide, and least visible when it is zoomed in to the Z99 max. With a 50mm lens at f/4 and the FX1 set to Z82 I noted a 5% dip in left edge brightness, and a 10-percent drop on the right edge of the frame. Wide lenses tended to exhibit more edge falloff, telephoto less. To virtually eliminate vignetting, you must zoom the camera into Z94, where on the 50mm I noted just a 2% drop in edge illumination over the stock lens.
To deliver the best sharpness, the Brevis should be configured with the camcorder lens set as wide as possible. The reverse is true if you wish to eliminate vignetting. Bear in mind also that the focal length of the camcorder has a direct effect on the field of view of your final image. Users will find that obtaining optimum sharpness and an evenly illuminated frame at the same time is a balancing act and requires compromise.
The Brevis Flip is quite light and can technically be used without a rod support system, but I would not recommend it. The system works best when properly supported by standard 15mm rods and the Brevis support bracket. Many third-party rods and adjustable baseplate solutions are available. Cinevate also offers its own carbon fiber 15mm rods and camera baseplate.
Brevis Flip 35mm Lens Adapter
$1,405
DV Score:
Pros:
Virtually no vignetting when properly configured. Interchangeable imaging elements and reliable lens collimation adjustment.
Cons:
Built-in rechargeable battery cannot be swapped in the field. Attaining perfect sharpness and zero vignetting at the same time is virtually impossible; users are forced to choose one of the two.
Bottom Line:
A compact, modular design and good resolution and edge sharpness when properly configured.
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