Cinevate Brevis Flip 35mm Lens Adapter Review (Part1 of 2)
By Matt Jeppsen

Cinevate
www.cinevate.com
(647) 723-2664 (Canada)

The following is Part 1 of FreshDV’s two-part test and review of the Cinevate Brevis flip adapter. Today we cover an Introduction, Imaging Elements, Design and Construction, and Setup and Configuration. Read on for Part 2 which addresses Image Performance and Workflow, Accessories and Miscellaneous and Summary and Conclusions.

Introduction
The last few years have seen an explosion in the use of small-format HD and HDV cameras for production. So-called “prosumer” and even some consumer-oriented camcorders are in wide use by amateurs and professionals alike. One market that has also been growing in leaps and bounds are 35mm lens adapter systems. This review takes a detailed look at the latest revision of Cinevate’s lens adapter line, the Brevis Flip. In addition, we will examine the latest in their series of swappable imaging elements, the CF1Le diffuser.

Background
In lens adapter systems, the image from a 35mm lens is projected inverted on a ground glass or textured imaging element. The camcorder in use focuses on and captures the image projected on that imaging plane. And without an optical method of flipping the image upright within the lens adapter, it is recorded to the camera in this inverted fashion. Now recording a upside down image is not necessarily a problem…it is a relatively simple task to rotate video upright in most NLE’s. However, the issue becomes a bit more problematic when monitoring during the course of a production shoot. If the image your camera is recording is upside-down, obviously the image in your viewfinder and LCD will also be inverted. This makes framing and tracking shots quite difficult. There are a number of ways to deal with this, from using magnets to activate the camera LCD’s frontward-facing LCD inversion feature, to mounting an external monitor upside down and using that for composition and framing. But by far the simplest solution is a 35mm adapter that optically produces an upright image.

Overview
As you may have guessed by the name, 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 Flip unit attaches to the camcorder’s filter threads, while the portion of the unit that contains the array juts downward to a lower level tube where the actual imaging element, lens mount and lenses attach. The Brevis Flip can be mounted to the camera with the vertical-offset in either the upper or lower configuration. It is technically light enough to use without a rod support system, but I would not recommend it. I was pleased to note that the offset design is svelte enough to rotate freely underneath (and not contact) the built-in microphone that sticks out on the front of Sony HVR-Z1U, HVR-V1U, and PMW-EX1 camcorders. This new Brevis Flip model includes a improved achromat as well, which results in less fringing and chromatic abberation in the image than previous Brevis revisions. Current Brevis owners can upgrade to the Flip unit by simply removing their Brevis from it’s achromat lens, and locking it onto the front of the flip unit with the included hardware.

The Cinevate Brevis Flip Bundle includes the following:
* Brevis35 HD lens adapter (with micro-collimation lens mount system and interchangeable imaging elements)
* 72mm Achromat lens (step up/down rings are available and work seamlessly)
* Brevis Flip module
* Lens mount of your choice (Canon EOS, Canon FD, Nikon, Minolta MD, Pentax K, Pentax M42)
* A/C Adapter/charger
* Pelican hard case
* Allen wrench
Note that a PL cine lens mount upgrade is available at a premium cost. Cinevate offers a OCT19 mount option as well.

Imaging Elements
When ordering the Brevis, you have the choice of one of multiple “Cinefuse” imaging elements, called diffusers. The diffuser is the image plane of the 35mm adapter. It is the textured or grained area that you focus your camcorder on, and the part that essentially projects the image from your 35mm lens. As you can imagine, this is a very critical part of a 35mm adapter system. Cinevate offers six discrete elements that can be used in the Brevis. Cameras equipped with filter threads sized under 58mm should use the CF1, CF2, or CF3 elements. Larger cameras with filter threads over 62mm tend to perform better with the CF1Le, CF2Le, and CF3Le options. The “Le” designated diffusers are tuned to deliver better edge sharpness and reduced vignetting across the typical lens range. The brand new “Le” series replaces the previous “L” versions, and deliver better vignetting performance on cheap and slow wide lenses (typically wide lenses tend to have more light falloff, and therefore can cause image vignetting).

Each Cinefuse option contributes a different look to the image, particularly the out-of-focus areas of the frame (or “bokeh”). Essentially, the CF1 elements offer the least diffuse bokeh, and therefore deliver the appearance of deeper depth of field. However, they are the most light-efficient of the Cinevate diffuser elements, and are therefore considered a good choice for general purpose production work. The CF2 series of elements offer higher levels of bokeh diffusion over CF1, and therefore create slightly more pleasing image bokeh at the expense of an additional half stop of light. CF3 increases the background diffusion even more over CF2 and of course has a bit more light loss. CF3 is generally regarded as creating the most filmic image of the imaging elements Cinevate offers. CF2 and CF3 are suggested for use with fast lenses at the lower end of the f stop scale. Please bear in mind that discussions of “good” vs. “bad” bokeh tend to be very relative. Everyone has their own opinion on what looks good. For the purposes of this review, we will be using a Brevis equipped with the CF1Le imaging element, with some comparisons to the part it replaced, the CF1L.

Opening up the Brevis and swapping a Cinefuse diffuser is a relatively straight-forward task that can be accomplished in about 5 minutes with some practice. It just takes a flat surface, allen wrench, and a Phillips screwdriver. I recommend that you perform imaging element swaps in a clean, controlled environment so as to limit the introduction of dust to the inside of the Brevis imaging tube. The fact that you can change the essential characteristics of your 35mm adapter image with a simple element swap is one of the characteristics of the Brevis adapter that I find most attractive. You can essentially to tune the image based on the needs of a particular project. Shooters can use an extremely light-efficient CF1-series element for general purpose projects, and have the option to add a CF2 or CF3 series Cinefuse into the mix when low light isn’t an issue and they need a slightly more filmic image.

Design and Construction
The Brevis is solidly constructed of milled aluminum and carbon fiber. All metal surfaces are powder coated with an optical flat black finish. Cinevate has informed me that they are now introducing surface hardened anodizing as the standard finish. I’ll describe the design by starting from the camcorder filter threads and work towards the front of the adapter. The achromat lens is secured to the back of the flip unit body. A small amount of adjustment is built in so you can fine tune your camera’s alignment with the achromat. This is important, as so many camcorders seem to have a variance in sensor alignment. No one size truly fits all, and the Brevis can be adjusted to account for these slight variations. The prism flip unit juts downward and is encased in a smooth milled aluminum shell that feels very tough and looks like it can withstand the rigors of production work. At the bottom of the flip unit there is another round 72mm “window” that the actual Brevis imaging tube attaches to. This is designed to offer a second alignment point. It also hosts 62mm threads which I am informed are for third party applications. The Brevis is locked to the Flip unit at this point with four allen head screws. I should note that the same fastener head size is used throughout this adapter, so you only need carry one tool for servicing and adjusting the Brevis adapter. The Brevis itself is a sleek carbon fiber tube with smooth aluminum ends. The power switch and charger plug are located on the back of the Brevis, in the metal end cap. The front of the adapter tube has the lens mount collar with a micro-collimation ring inside that can be used to fine-tune the adjustment of your lens mount, ensuring the feet and meter markings on the lens itself are accurate. This design is very simple to use and really takes the pain out of lens collimation in my opinion. As a side note, due to the diameter of the PL and OCT19 cinema lens mounts, they actually enclose the front lens collar and lock down in that fashion. Adjustment of the larger cinema mounts is independent of the SLR film lens mount collimation. This ensures that your SLR collimation remains consistent. However, it also means you should take time to micro-collimate the PL and OCT-19 mounts if/when you attach them to the Brevis.

The Brevis flip unit completely assembled measures about 5 and 3/4 inches in length from the back of the flip unit (the achromat threads) to the lens mount. This is actually quite close in length to the pre-flip adapter, which measures just under five inches from the achromat to the lens mount. Camcorders like the Z1U that require an extension tube to achieve proper close focus can add about 3/4 of an inch extra length to the pre-flip unit. However, the Z1U doesn’t require an extension tube with the flip unit, so the total length of the unit doesn’t really change for those particular users who wish to upgrade to the flip. So if your current setup doesn’t require an extension tube, the flip version is going to add another 3/4 of an inch in length to your rig.

Setup and Configuration
Setting up the Brevis Flip unit with your camcorder is a relatively simple task. It may seem a bit confusing to new users, but once you do it a few times you will get the hang of it. That being said, there are a number of considerations that should be addressed if you wish to achieve optimal image results. For starters, I have always recommended that you base everything on a good set of 15mm support rods. The Brevis and Flip unit along with a typical 50mm SLR lens weigh only a few pounds fully configured, but that weight resting solely on camcorder filter threads concerns me…use support rods! Cinevate offers a riser plate that locks to your camera’s 1/4-20 mounting thread and tripod plate, and it supports standard 15mm rods. You should use that riser along with the adjustable Brevis tube support. There is plenty of adjustable range in both mounts to elevate the rig high enough to accommodate the flip unit’s vertical offset. You can mix and match other brands of riser plates and rods as the Cinevate hardware is all industry standard in design. But for this test Cinevate provided me with their new solid carbon fiber rods and the latest tool-less revision of the Brevis support mount. Both are beautifully designed. The 15mm carbon rods used for testing are the 45cm variety (just under 18â€?), Cinevate offers them in 30cm and 60cm as well (approx 12â€? and 24â€?, respectively). They address one of the issues I have personally noted with the previous revision of Cinevate carbon, namely a widely varying thickness down the length of the rods. This latest carbon revision showed near perfect width tolerances in my testing. And being solid, they offer more stiffness. Cinevate claims 75% stiffer than steel. After using the solid rods for a while, I can’t argue with that…they are rock-solid. The new tool-less Brevis support mount specifically addresses a wish we noted in one of our 35mm adapter tutorial videos. This new design makes setup and configuration a breeze! I sincerely appreciate that Cinevate has a pulse on the community and is willing to re-design and engineer around users issues. Good form!

For this review and test I used both the Sony HDR-FX1 HDV and the new XDCAM PMW-EX1 camcorder. The setup process on both cameras is almost identical, but I’ll refer to the EX1 here. I mounted the EX1 camera to the Cinevate riser plate and attached that to the Cinevate carbon rods and baseplate. Quick note…for this test I was using a medium-weight Manfrotto tripod with 501 fluid head. It handled it, but a heavier duty tripod head might give you better performance…I felt like this rig was pushing the limits of the 501 on some pans. After attaching everything to the tripod, I adjusted the riser plate so there was a few inches clearance between the bottom of the camera and the rods. About 3 inches seemed to do the trick.

Now I personally own the Brevis pre-flip adapter; it is the model with the latest micro-collimation adjustment option. So this setup process will cover the entire process of attaching a Brevis imaging tube to the flip unit upgrade parts that Cinevate provided me with. For starters I removed my previous revision achromat and a 72mm extension tube from the Brevis carbon tube and attached the imaging tube to the flip unit using the allen head screws to lock it in place. I recommend not tightening everything down completely at this point, more on that in few moments. After removing the EX1’s stock lens hood, I threaded on a 77 > 72mm step-down ring. Pretty much any brand will work (use the metal variety), and Cinevate stocks a variety of step rings for common applications. The next step is threading the upper/achromat side side of the flip unit onto your camera front threads. Always take your time with this and support the entire flip unit and Brevis tube with your other hand. I like to tighten this on the threads until it is just finger tight, since most of the weight will be borne by the rod support system. I then loosened the allen screws that secure the achromat and rotated the flip unit until it stood perfectly vertical. This is also a alignment point if you need it…you can watch the camera LCD and adjust the flip unit X and Y to line everything up perfectly with the imaging element “window.� If you’ve done this right you shouldn’t have to adjust the allen screws again. Just thread on the unit until it stands vertical.

Next I slid the Brevis adjustable support onto the rods and raised it up till it bore just a bit of the weight of the Brevis imaging tube. You want it to bear weight but you don’t want to push it so high that it stresses the camcorder threads upward. I always try to place the riser mount’s lower shackle on the carbon tube, right behind the metal end that attaches to the lens mount. This is easy to accomplish with most equipment configurations, generally there is plenty of space on support rods with this setup. Before putting the top clamp on I turned on the EX1 and looked through the viewfinder to ensure the Brevis imaging element “window� was square to my camcorder’s image frame. If not, you can simply loosen the four allen screws that secure the Brevis tube to the flip unit and rotate it as needed. I prefer to position mine with the on/off toggle switch, power light, and charging plug on the top of the unit. Once everything is squared up, put the top clamp on the Brevis and lock everything down (did I mention that I love this tool-less clamp design?). I then locked a 50mm Nikon lens to the lens mount, closed the aperture down to f/16, and aimed the camera at a lit white card. On the EX1 camcorder I engaged full manual modes for zoom, focus, shutter and aperture. 1/60 shutter and f/1.9 iris settings are a good start. Looking through the viewfinder I slowly zoomed into the “window� until I fully cleared the outside edges of the Brevis imaging element. The EX1’s overscan LCD makes this easy to determine. On cameras like the FX1 without an overscan mode you’ll want to zoom in further to ensure you clear the edges of the imaging element, or use an external monitor that shows the entire frame being recorded. One of the things I immediately noticed was how much more zoom room I had to operate with. Sony small-format HD cameras tend to have rather poor macro lens performance, and need a spacer tube added onto a pre-flip Brevis to attain proper close focus. Between the need to zoom in enough (to clear the diffuser frame) and the limits of the stock camera lens, there is very little margin for focus adjustment. The Brevis flip unit however has no such needs for either the FX1 or EX1. You can zoom in the entire focal length of your stock lens if necessary, which makes attaining focus on the imaging element MUCH easier. So I did. I zoomed in all the way, engaged the camera’s peaking mode, and manually focused on the imaging element grain structure. Between peaking, the ability to zoom in fully, and the XDCAM EX1’s beautifully sharp LCD, attaining perfect focus was simple. There really is no need for an external monitor for this task. And if you need a little help, you’ve also got the camera’s focus assist function. After focusing on the imaging element grain, I locked the camera focus ring down with a strip of gaffer tape on the lens body. I then zoomed back out to a wider focal length, just wide enough to give a nice usable field of view without showing the edges of the imaging element. After attaching a Redrock Micro follow focus and turning on the Brevis power, I was ready to shoot test charts.

Continue reading this review with Part 2.