Test Drive: Cinevate Brevis35, Part 2

Figure 1. To those who doubted my ability to successfully assemble these disparate parts (including you, Mom), here''s the assembled unit!
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I know, it''s been two weeks since I left you hanging with the receipt (but not the use) of the Cinevate Brevis35 imaging system. In this episode, I''ll take you through assembly, alignment, and configuration of the unit and reveal the first images shot with my now supercharged Canon XH A1 (Spielberg, watch out! I''m coming). OK, I''ll calm down. Truthfully, though, this process has been intensely interesting and fun, and if the early results are any indication, more than worth the effort.

Let''s start with a look at the assembled unit. On the right is the base Canon XH A1, with the lens hood off and the Brevis with Flip Module attached. On the extreme left is the 35mm Canon lens, and the entire rig is sitting on and supported by the 45cm rails system. Pretty sweet.

Of course, assembly is just the first stage, albeit an important one. Beyond this are the three stages of configuring the unit, or alignment, focusing the camcorder, and collimation. Let''s take this one item at a time (and yes, there will be a test).

Figure 2. Aligning the adapter.
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Step 1 is alignment. Essentially, you''re screwing a tube to the end of your camcorder, and then shooting through the tube. If it isn''t properly aligned, you won''t get the optimal results. As I mentioned in the first article, you attach the Brevis Flip Module to your camcorder via four set screws in a ring that sits outside your camcorder''s lens, similar to how you would attach a lens hood or matte box.

To align the unit, you loosen the screws, point the camcorder in the air to lessen the weight of the adapter (hence the picture of my air-conditioning vent), and then jiggle the lens around until the opening is squarely in the middle of the frame. In the figure, I probably could rotate the lens perhaps 1/4in. counter-clockwise, and perhaps a few millimeters to the right. When you''re perfectly centered, you tighten all the screws to set the alignment.

Then, using the camcorder''s zoom control, you zoom the image in until all the edges you see in that sexy shot of my office ceiling are gone. Then you save the zoom position, because as long as you have the adapter attached, you''ll never use it again.

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Test Drive: Cinevate Brevis35, Part 1 Like most shooters, I''ve encountered many situations where I wished the 3 1/3in. CCDs on my best Canon and Sony camcorders could produce sufficiently shallow depth of field to allow me to blur out irrelevant sections of the frame. Perhaps it''s the ability to blur out the background in an interview or training video, which hides lots of flaws in the back wall...

Why is that? If you think about what''s going on here, it works like this. You''ve attached a 35mm lens to your camcorder. That lens sends the image back to where the CCD would sit in a regular 35mm camera. What''s there instead is the image element of the Brevis adapter. What you''re trying to do during alignment is to frame the camcorder as closely as possible to that image element. In essence, with your camcorder, you''re trying to take the best picture of the picture captured by the 35mm lens. If you zoom into the picture with the camcorder''s zoom lens, you''re actually focusing on a smaller chunk of that picture, which can degrade quality.

Figure 3. Setting the camcorder''s focus.
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This picture-of-a-picture concept also helps explain the next concept, which is focusing your camcorder. Essentially, now that you''ve framed the image by aligning the unit and framing the picture element, you have to focus your camcorder on that picture element. You do this by stepping down the f/stops on your 35mm lens and pointing your camcorder at a bright object—which, in my case, was the Apple Cinema monitor I was using to write this article.

In this condition (high f/stop, bright object), the grain in the image element becomes clearly visible, and you can focus the camcorder on that, especially with peaking enabled. That grain is what you see in Figure 3.

Focusing on this grain leads to a couple of very obvious questions: First, why does this grain have to exist at all, and why doesn''t it show up in the video that you shoot? Remember, the purpose of this element is to replace the film that the lens is expecting and to capture the image from the lens in a form that the camcorder can capture. The grain has to exist because if the imaging element were perfectly clear, the image couldn''t form on that glass, and the camcorder couldn''t capture it.

Why doesn''t the grain show up in the video? Because when the Brevis unit is powered up, the diffusion element oscillates very quickly, which eliminates the grain but retains the image. How? OK, it''s magic. What can I say? I''m not an engineer. Still, I do know that if you shoot without the Brevis running, the grain will appear in unfocused regions of the screen, looking frost-like, and almost like an Adobe Photoshop effect.

OK, almost home. We''ve aligned the unit and set the camcorder''s focus. Now we have to set the unit''s collimation. According to the Brevis manual, collimation is “the process of setting the distance between the lens mount flange and the film plane (imaging element).”

This gets back to concept of the imaging element of the Brevis unit replacing the film in a 35mm camera. In the still-photography world, the cameras and lenses are precisely manufactured so that the image from the lens projects precisely on the film; otherwise, the picture will lack focus. When you attach a 35mm lens to your camcorder via the Brevis, you have to position the lens the same precise distance from the imaging element; otherwise, it may not focus properly. Collimation also ensures that when you dial the lens to focus at 2 meters, it actually focuses on an object 2 meters away.

You collimate by setting the camcorder up a fixed distance away from a focus chart and using an internal ring on the Brevis adapter to adjust the distance of the focus mount to the imaging sensor. This sounds complicated, but there''s an online video and several pages in the Quick-Start Guide that will help you get it done in about 5 minutes or so.

While this all sounds pretty daunting, if you budget one hour for the entire process, it should be more than sufficient.

Figure 4. Here''s the setup.
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The proof of the pudding is in the eating, so I set up the shoot shown in Figure 5. The subject stood about 3ft. from the camcorder and about 4ft. from the back wall, and I was shooting with the 35mm lens set to maximum aperture.

Here''s a frame shot with my subject in focus:

Figure 5. The back wall is about 4ft. away from the subject.
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Here''s a frame shot with the back wall in focus:

Figure 6. Same distances, back wall in focus.
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Overall, with this setup, the depth of field was pleasingly shallow, and with two subjects only 2ft.-3ft. apart, you would have no trouble selectively focusing on either, with the other out of focus. Basically, the Brevis more than worked as advertised, and it is a relatively inexpensive (compared, say, to a Red Digital Cinema camera) option for creating that filmic look.