Centering image on HVX200 with Brevis Flip, anyone with success?

J

Joe Kocsis

Well-known member
I cannot get my image centered with the flip. I have adjusted at all points of so called adjustment point.. 3 of them if I recall correctly while sitting here..
I can center it with the non flip.

Is anyone with an HVX200 able to get their image centered with the Brevis with Brevis Flip?
 
Hi Joe,

I m using HVX and the Brevis with flip. So far my Brevis with flip is pretty close to centre. I guess it is hard to be perfect edge to edge centre. But I have mine satisfying close to centre. How bad is it for yours? Try going back to Cinevates Video University and try adjusting it again. Or you might want to check out the forum before emailing Dennis for help.

Has anybody else got the image really centre with flip?
 
Joe, every HVX200 is different, and nearly none of them we've seen have the camera's CCD block direclty centered. In other words the issue is with the HVX200 itself, not the adapter...and indeed why we came up with the term XY adjust in the first place. If you back off the screws completely on the Brevis/flip couper (V ring) you'll get about 1.5mm of adjustment, and then another .5 or so at the flip achromat. It's highly unlikely your HVX optics are that skewed, but read on. Our adapter is CNC machined and the imaging element plates are installed using a highly accurate assembly tool. You can confirm this by rotating the Brevis unit 180 degrees on the flip. You'll see that your XY issue does not go away when you do this, which tells you the HVX imaging block is off-center.

One of the ways you can tell definitely is to use something like a 82-55 step down ring on your bare HVX, or make yourself a paper ring "doughnut" (using a graphics program) so the "doughnut" has an OD of 82mm and and ID of 55 or so. Cut it out so there's a hole in the center. Alternativey, center a 16:9 ratio frame in the middle of the 82mm circle and cut that out. Put this paper template over your HVX200 (using the camera's 82mm threads to center your 82mm graphic) bare lens and zoom in. Eventually as you zoom in you'll see that the hole is not centered giving you a visual reference as to how offset the captured image is. If you need further help, just give us a call. We can give you visual overview via conference using SKYPE or OOVOO for free. OOVOO provides a web based interface so you don't need an account..just a web browser.

Cheers,
Dennis.
 
I adjusted at all points, and it went from extremely off, to not great.

>You can confirm this by rotating the Brevis unit 180 degrees on the flip.
> You'll see that your XY issue does not go away when you do this, which tells you the HVX imaging block is off-center.

I don't doubt that all HVXs are mildly off center.

However,
It seems to me that the FLIP unit itself does not have a perfectly straight light path, and that the prism is slightly skewed. If the actual path of the FLIP was true rotating the FLIP unit 180 degrees should not improve centering. However, it appears that many have actually seen this improve their center, and is the only way for them to achieve it.(this is documented on a thread on your forum under the FLIP subforum). Someone suggests this as a work around in the thread on your forum, although its ridiculous, because all my accessories also woudl then have to be jacked sky high.
 
try rotating the brevis, not the flip. That may help if the imaging element is not center.... or if it's the flip, try flipping + rotating the flip instead of just rotating if you dont want to go snorkle up... ack nevermind i think that may get you the same results.. i think..
 
I just paid over $800- for the FLIP over $1000- if you include the new baseplate.. I didn't expect to have to TRY anything. I expected it to be designed to bolt on and work correctly.

The other thing I've noticed is that the unit has become more sensitive to higher shutter rates with the flip on than without it.. When shooting in slow-mo like 720p60 180d I get a pretty significant strobing that is barely detectable without the flip. thats 1/120 shutter speed.. 1/60 is fine.. It's nice to have an upright image, but overall It's been pretty disappointing thus far.
 
hey, like Dennis said, the alignment issue is a camera issue not the brevis. I don't think there's an adapter that exists today that you can just slap on. Even my sgblade required adjustment to get it right. They all require tweaking to work since all cams are different.
 
Also, if you can frame an 11" wide object(like a 8.5"x11"paper), at 2 feet away from the focal plane, using a 50mm lens, then you are at academy framing. If you can't because you had to zoom in too much, then yeah, the centering is not acceptable.
 
Well when I say try.. I'm talking about spinning and reversing... etc..

I've worked with the Brevis for a while.. I have had good results with Brevis without the flip. I also have it dead center..

I have other issues with the FLIP outside of just the centering, like the one mentioned above in regards to shutter speed.. I dont know why it does it.. but it does, and it's a problem..
 
Joe, with respect to alignment, it's for sure not the flip. It actually adds quite a bit more adjustment than the non-flip unit. The flip btw, is symetrical and can be used either way, with no issues. It's in a CNC machined case with a bonded prism array...so even with stack tolerance it is for all intensive purposes, perfectly aligned. You're correct in that with the camera's XY issues aside, you shouldn't need to mess around. I do know after experience with literally hundreds of HVX200s out there, not all of them can be aligned perfectly. However, if you can align the non-flip unit to your HVX200, then the HVX200 has to be nearly perfect in terms of alignment and I'd suggest making sure your flip achromat and Brevis/flip interface are 100% flush to each other as even a slight issue there would give the symptoms you describe. The tolerances inside the flip are so tight, if it was not aligned, the prism array would already be broken.

On the oscillation/shutter issue, I'd be about 95% confident that the increase in the rig's mass (if oscillation was tuned in the non-flip mode) is what you're seeing. The MP.1 and MP.2 both allow tuning the microprocessor's oscillation control on the fly, and completely rigged. We recommend this because you want to set it (as the videos suggest) with a fully rigged unit on tripod. This has the highest "fixed" mass and therefore is how you should tune it. If you're handheld, on a sandbag or otherwise, the relative oscillation will always be a bit less..and therefore never an issue. At 1/120 you actually want to reduce oscillation speed slightly, and at 1/48, you can increase it.

If there's any way we could arrange a SKYPE session with video, I'm confident we could sort the issue very quickly. That way we can look at your setup directly.

Hope that helps,
Dennis.
 
You must log in or register to reply here.
Back
Top