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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

TEST/REVIEW - Motion Mount on Helium

Christoph Tilley

Christoph Tilley

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Pretty sure the Motion Mount isn't working as intended on Helium sensors, which is quite unfortunate. The color shift shouldn't be this bad.
 
It was a while back I used it . But I think the whole idea with the motion mount is the sinewave shutter. The "global" square shutter is not much better than the rolling shutter that is in use when not having the motion mount. And I think the square option in the settings are more to let in more light than the sinewave option can do.

My guess is that the helium color science work is still in progress and the motion mount depending parameters are possibly not in priority at this early stage.


So how is it preorming without ND and in sinewave mode. As thats really what it´s built for / to create a sinewave typ motion blur. Hench the name motion mount instead of ND mount I guess.
 
Pretty interesting. One thing to note with the motion mount is that when changing the ND value you have to wait a second or so for the camera to adjust/compensate the colour shift and it won't do that if you change the value while rolling, for example. That said I haven't used mine on a helium sensor as of yet.
 
The motion ghosting happens because the sensor cannot read fast enough at 8k for the motion mount's global shutter to work. If anyone's curious why I can draw a picture explaining why that is, but ultimately the helium sensor is at fault, not the motion mount.

I found that 8kWS with 1/50th second shutter does draw a global frame with the square shutter at 24fps, so that height in pixels should be around the threshold for normal cinema settings. I wonder if this is how they shot The Underdog since the motion was so nice.

One other artifact that can occur with the square shutter, extreme highlights that are well beyond clipping will also ghost, and there's nothing you can really do to stop this artifact. This is because the sensor is running opengate, 360 degree shutter behind the motion mount, which acts as the shutter by rapidly turning opaque and clear. It's opaqueness is around 9 stops of ND, not a full opaqueness like a metal mirror shutter. Anything that can get a signal through 9 stops of ND will have 360 degree shutter motion blur, while the rest of your image has 180 or whatever you set it to. This is only really a problem with bright bulbs in a black room, that sort of thing, where the motion blur of the bright object 9 stops down is enough to register against the otherwise captured image.

The sine wave mode, "soft shutter", seems to demand even more from the sensor and I think I found it working at around 4kFF 1/60th at 24fps. But the motion artifacts will always only draw at the bottom of your frame and the sine wave artifacts benefit from the sine wave shutter, making them softer.
 
I'd also mention that the mount is essentially a polarizer. Screens can look strange, or sometimes black with the mount. I love the motion mount, but I think this review nailed it's shortcomings.
 
Supper great review and explanation of the Motion Mount. Its the kind of explanation that will help a lot quickly understand how to get the most out the their Motion Mount. And what things to avoid or be aware of.
One thing that I feel is sometimes over looked is the ability to ND lenses that have almost no way to filter using the MM. These are lenses that would otherwise not be able to be filtered or would need a complete set just for that lens.
Supper wide lenses and speciality lenses.. And I have to say that to have the MM on when Im using a Telephoto lens like say a 400mm prime it is invaluable for a quick ND change.
Hopefully some of the concerns can be remedied over time.

Thank you Christoph
 
This is amazing. For the longest time I didn't understand some of the pitfalls regarding the motion mount. I do have a question regarding captive vs non-captive. Is there a difference between the two filters besides screws?
Thank you very much for this.
 
I will just say that the color shifting I am getting with the "new motion mount" is insane, really really bad. I even get a yellow banding which looks like a sunset grad if I max out the ND in the Motion Mount. -

Epic W Helium (latest firmware October) Skintone OLPF

Brook Aitken
DP
Boulder CO
www.brookaitken.com
 
MM is not to be used wide open you have to stop down a bit, otherwise at some high value you get the weird color shift in the bokeh (not the normal color shift in the image). It's mentionned on Red website if I recall.

I've never had any trouble with my PL MM on Dragon (I only use ND only) when using it within Red recommendations. The camera adjusts the color automatically and it matches enough the footage so it's not grading dramatic at all.
 
brook aitken said:
I will just say that the color shifting I am getting with the "new motion mount" is insane, really really bad. I even get a yellow banding which looks like a sunset grad if I max out the ND in the Motion Mount. -

Epic W Helium (latest firmware October) Skintone OLPF

What are your settings? The strength of the ND or shutter setting on the MM the lens your using and the f stop your using. Or do you see the color shift at all settings.
Maybe a R3d file to let some of us take a look.

Make sure you don't have things like HDRX turned on if you can even turn it on with the MM on the camera Im not sure, and in my experience some higher frame rates vs shutter angles, don't play well together but you can almost always adjust a bit on each and find one that works.

Like Berenger said if you play with in the guidelines that RED has said work it is a gem of a tool to have on the camera... When you ask it to do the max ability on any of the settings you start to notice artifacts but those are usually the extreme settings.

And Shawn, I would think that there should be no difference between captive vs non captive screw other then you have to hold the screws when changing the mount.
Click to expand...
 
I created a ticked and am now send in the motion mount to Red. No HDRX, ND only, kept it pretty basic. The shifting was pretty massive and would just start to bake in the yellow grad tint randomly. I don't have the footage so I cant share RD3 but hopefully you can see the images in my Dropbox link, (if I shared correctly)
IMG_9537.JPG


https://www.dropbox.com/s/pxhowygeyo7yve0/IMG_9537.JPG?dl=0

https://www.dropbox.com/s/pxhowygeyo7yve0/IMG_9537.JPG?dl=0

will have to see what RED tech says-

Brook Aitken
DP
Boulder CO
www.brookaitken.com
 
I just wrapped a 3 days shoot before christmas, with Helium and Motion mount all the way. The first I did with that combo.
With Celere lenses, and slowmotion at 90° and 180°. Prores only (I just hate that mode it's not good enough in 4k, I always have to explain the director why slow-mo is 2k only).

I must say it was a pretty weird combo. We had all sort of abberations, from shutter trouble (the bar in the middle, black or colored) to insane flaring (Celere are already too flary, and it was worse).

And color shifts in shot (like, switching 5600° to 3200°). Really weird and really random. It didn't occure during the test.

Anyone had this happened ?
 
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