Video Assist not wysiwyg?

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Patrick Baldwin

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Video Assist not wysiwyg?

PostSun Nov 19, 2017 6:03 pm

I have 5" and 7" video assists and I have noticed that when I monitor from my FS5, either SDI or HDMI, the monitors don't seem to truly represent what the highlights are doing. I was aiming for a white background but could see some detail still in it on the VA's but it was completely blown out when I downloaded the footage. I have had a similar experience where clouds have appeared to hold detail but have been overexposed once I downloaded it. I am not using any luts or shooting in Log. Would anybody know what I am doing wrong?
Best wishes. Patrick.
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Denny Smith

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Re: Video Assist not wysiwyg?

PostMon Nov 20, 2017 5:19 pm

You really over exposing the sensor on your camera. Set your camera Zebras to 95% and keep the exposure below this level. The VA is displaying the processed video,out from your camera, and may not be indicative of what your sensor is doing.
Cheers
Denny Smith
SHA Productions
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Patrick Baldwin

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Re: Video Assist not wysiwyg?

PostTue Nov 21, 2017 12:16 pm

Thanks for taking the time to answerDenny. My zebras are set to 95%. I was aiming for a blownout background but in order to achieve it according to the VA's I had to give it more light which when downloaded showed some considerable flair/wrap back onto the subject which wasn't evident on the VA. I'm missing something here. I thought the whole point of the VA and such like was to show you what the camera was doing otherwise how do I judge it properly.
Best wishes.
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Denny Smith

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Re: Video Assist not wysiwyg?

PostWed Nov 22, 2017 1:57 am

This would only work if the various cameras video output actually reflected what and how the camera was recording the data. Unfortunately, this is not the case with a lot of prosumer camera’s and low to mid range Pro cameras. That is why I set Zebras on the camera, not on the VA, and have this overlay available on the camera output (again this is not possible on some cameras also). Camera Zebras usually, but again not always, will reflect what the sensor clip level'is for exposure. BM cameras work this way.

With time and practice, and some testing, you should be able to get a feel for how the camera is recording compared to its video output image. This is where other exposure tools like waveform and vector scopes come in handy, along with false color *which is like a IRE spot meter at various IRE levels.
Cheers
Denny Smith
SHA Productions
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Patrick Baldwin

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Re: Video Assist not wysiwyg?

PostWed Nov 22, 2017 10:19 pm

Thanks again Denny. I was actually using the cameras zebras but as you say I guess I will just have to learn to interpret what I'm seeing. I was actually using the waveform and false colour on the 7" as well.
Many thanks for taking the time to respond.
Best wishes. Patrick.
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Robert Niessner

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Re: Video Assist not wysiwyg?

PostThu Nov 23, 2017 9:22 am

Patrick, I am quite sure your highlights are not blown out. Most cameras - when not shooting log - make use of so called super whites. With 8bit material that means all RGB values above 235 are super whites and may appear clipped when loaded into e.g. Premiere Pro. However those super whites are not lost and can be pulled back. This is just how Rec.709 works.

To do this for example in Premiere Pro you can put a RGB curve effect onto your clip (for example at your master clip). Using the RGB-parade of the Premiere Pro reference monitor you can visually see how much can be restored. Just drag the upper right end of the RGB curve effect Master Curve a bit downwards and you will see your blown out whites coming back.
Robert Niessner
LAUFBILDkommission
Graz / Austria
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