URSA Viewfinder motion judder at 25p

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Rakesh

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URSA Viewfinder motion judder at 25p

PostWed Jul 11, 2018 3:39 am

I have recently purchased a BM viewfinder for my BM Mini Ursa Pro.
We shoot PAL 25p in HD as a standard procedure like we do with our other cameras.
When shooting in this frame rate the Viewfinder shudders when panning/tilting camera.
When shooting at 50p the viewfinder is smooth.
We would only shoot in 50p if we were going to use shots in slo motion.

Is this how the viewfinder is designed?

Anyone else with this issue?

Would have liked to know this before we went down the BM road.

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Denny Smith

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Re: Black Magic Viewfinder performance

PostWed Jul 11, 2018 5:07 pm

At 25p, you need to pan and tilt the camera very slowly and smoothly to get best results. Move it too fast, and yiu will get the shudders, as the movement is faster than the frame rate. The larger the sensor, the more this becomes evident.
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Denny Smith
SHA Productions
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Rakesh

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Re: Black Magic Viewfinder performance

PostWed Jul 11, 2018 11:05 pm

Thanks Denny for the reply.

The viewfinder also shudders when stationary but subjects is moving ie cars/walking people.

Kind of unusable when using in 25fps. The LCD is fine at this frame rate, which I can use but cant when handheld on my shoulder.

Seems like a strange behavior or is that everyone now shoots on 50p/60p and hasn't seen this?

Im in two minds now to shoot in 50P (pal) so i can use the viewfinder or shoot in 25p and avoid being shoulder mounted to avoid viewfinder....
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Rauno Linnamäe

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Re: Black Magic Viewfinder performance

PostThu Jul 12, 2018 3:56 am

In my opinion the EVF shudder got worse after firmware 4.8. I haven't had the time to arrange for a second EVF to do a proper side by side comparison but after switching between 4.1 and 4.8 a couple of times I decided to stick with the older firmware. There's still some of the shudder inherent to OLED technology but FW4.1 seems to render motion more naturally. The only downside I have noticed is that with an up to date camera the EVF does not display the correct shutter angle in the status bar.
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Rakesh

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Re: Black Magic Viewfinder performance

PostThu Jul 12, 2018 8:47 pm

Thanks Rauno.

If this is true then the Viewfinder issue is a malfunction rather than a the way it designed?

Not sure if anyone from Blackmagic support has seen this post but it would be good to know if this can be fixed in an update.
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Tim Schumann

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Re: Black Magic Viewfinder performance

PostFri Jul 13, 2018 1:21 am

There is no difference at all in the motion reproduction on the Viewfinder between Camera 4.1 and Camera 5.1.1 software. If you have two URSA Viewfinders with the same brightness and dynamic range settings that are receiving the same SDI feed with these two different camera software builds loaded they will look identical. We have tested it here and they match exactly. The motion doesn't change.

Rakesh, if you are used to looking at 25 frames per second images that are captured at 1080i50 then looking at true 25p images in an OLED viewfinder may be a bit of a shock. For true 25p or 24p capture you need to be aware that there are certain speeds that you can move the camera without judder in the resulting image and anything faster than this will result in a juddery look. This has been the same with images captured on film for almost 100 years and is why in every cinematography handbook will have a formula or table for recommended safe panning speeds.

For those coming from broadcast backgrounds, which tend to use 25 frames per second capture with 50 interlaced fields or 29.97 frame per second captured with 59.94 interlaced fields, this can be a bit of a shock as you are no longer capturing motion sampled at 50 or 59.94 times per second, you are capturing at half of that. A true progressive capture without interlace.

This is further compounded by the fact that OLED's have quite a fast pixel response and do not decay as slowly as LCD or CRT so this is most likely the difference you are seeing between your displays on camera and viewfinder.

Some other manufacturers camera / viewfinder systems have 'smooth mode's in them but you have to run the camera at 60p to smooth out the motion and send that to the viewfinder that whilst actually recording at 24, 25 or 29.97p... but the judder that you are seeing in our viewfinder is an indication that this is how your resulting footage will look so we figure you are better off to know this and have a clear indication of this in the viewfinder while you shoot.

If you find the judder objectionable and you shoot a lot of handheld content you may want to consider changing your shutter angle / speed. If this doesn't help then try shooting at a higher project frame rate like 50p, 59.94p or 60p, or even shoot with the same 25p project rate but switch to an off-speed frame rate of 33p, 48p, 50p, or 60p when you go handheld. The resulting images will be smoother and then you can decide whether to use those extra frames as slow motion or sped up to normal speed in post.
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Uli Plank

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Re: URSA Viewfinder motion judder at 25p

PostFri Jul 13, 2018 1:34 am

This text should be a sticky, Tim!
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Rauno Linnamäe

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Re: Black Magic Viewfinder performance

PostMon Jul 16, 2018 3:26 am

Tim Schumann wrote:There is no difference at all in the motion reproduction on the Viewfinder between Camera 4.1 and Camera 5.1.1 software. If you have two URSA Viewfinders with the same brightness and dynamic range settings that are receiving the same SDI feed with these two different camera software builds loaded they will look identical. We have tested it here and they match exactly. The motion doesn't change.


Thank you Tim, I'll give 5.1.1 a try. I did not have a second EVF at hand when I did the comparison (it was done in a controlled environment by upgrading/downgrading the same EVF unit) but with firmware 4.8 there was a subtle but nevertheless observable difference in the image - unless I imagined the entire thing, of course :)
Special Effects Supervisor / Key Grip / Managing Partner at Nordic Vision
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Tim Schumann

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Re: URSA Viewfinder motion judder at 25p

PostMon Jul 16, 2018 3:57 am

Flashing the viewfinder with 4.1, 4.8 or 5.1.1 will look the same unless you have different brightness or dynamic range settings applied to one of them. Viewing 'film' on one and 'video' on another might give a perceived difference because of the different contrast in the image.

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