Unfortunately I am disappointed. Iâ€™ve been building my own adapters for over a year, first static then oscillating so I had pretty high expectations and I know exactly what I want from an adapter, and I was nearly there with my own oscillator when I decided to buy the Brevis because I thought Dennis had solved the final problems I was struggling with.
The lens mount adjustment for correct infinity focus could be better. Itâ€™s difficult to ensure the lens is on a parallel plane to the GG, the surface the screws press against should at least be flat but it has grooves in it. When you tighten the screws the mount gets pushed out of line. What's the point in having micrometer accuracy on everything else if the final lens alignment relies on how the grub screws sit against the grooves on the lens mount?
Thereâ€™s no adjustment on centering the already small GG on the centre of the cameraâ€™s z axis which means further reduced field of view when you have to zoom in to get all four edges out of shot. The centre of the GS400 is not in line with the Brevis GG centre which means some wasted image area.
Furthermore the blobs of glue/tabs mounting the GG encroach onto the GG by a good mm on each side again reducing useable image area. The glue appears to have run or been rubbed into the fresnel grooves somewhat as well, and the diffuser has scratches near the edges.
The real disappointment for me is the bokeh. Itâ€™s bad bokeh... I took a risk jumping into the beta group without seeing a rack through a point source of light, but Dennis assured me there was no haziness when I specifically asked him about it... Hereâ€™s two comparison shots between my own adapter (POC 20 degree diffuser plus 2 x 120FL condensers) and the Brevis.
Brevis open aperture bad bokeh:
POC20 open aperture comparison good bokeh:
Brevis F4 better but still bad:
POC20 f4 comparison good bokeh:
The Brevis has hazy bokeh until you stop the lens stopped down to f4 or higher. Even then it's not as good as it should be. With the lens fully open it has the same characteristic haziness you get with a Beattie. It looks like the same type of diffuser with a fresnel, and the bokeh looks identical to the results I got with the Beattie.
Sufficient diffusion is a trade off against light loss, and since Dennis has also tested the POC 20 degree diffuser I find it hard to believe he didnâ€™t prefer the bokeh of the POCâ€¦ the light loss is about the same as the Brevis but the diffusion is better. Maybe it has too much grain, that's the final hurdle I haven't got over with my adapter, it doesn't move fast enough to eliminate the grain. The thing is, insufficient diffusion also increases the apparent depth of field, which is not what we want, and the DOF on the Brevis seems deeper than my adapter with all settings being equal.
Another let down is the noise of the Brevis - it's ok with the camcorder's own mic but the Rode videomic doesn't like it. A lot of bass rumble comes through even with the low pass filter on. Plus the end of the mic is right above the Brevis motor. Camera mounted mic is not an option with the Rode.
I'm sure plenty of people will be thrilled will the Brevis, but for me the bokeh is a disappointment considering the research Dennis has done. If you want your background lights/highlights to turn into nice discs of light like they do in the movies you need a sufficiently diffusing GG.
Sorry to be so negative Dennis, these are my first impressions, after specifically asking you about the diffusion of the bokeh I feel a bit let down...