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LCD screen Moire help


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#1 Dominik Bauch

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Posted 26 June 2017 - 12:40 PM

Just watched Deepwater Horizon over the weekend (great looking movie) and it has a ton of great c/u detail LCD screen shots. Where you really see the great texture of the LCD screens.

 

Using an Alexa Mini and virtually any cine lens, I've never managed to safely go above an 85mm without getting into Moire. But at that focal length I never get close enough to get the nice LCD pixel break up.

 

How do people achieve this? Deepwater was shot on an Alexa XT with Sumicron C's but I've used virtuall that same combination, same sensor and lenses but no joy.

Anyone have any insight or know how to go about this?

 

 


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#2 Phil Rhodes

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Posted 26 June 2017 - 02:51 PM

Quite often it's necessary to scale down the graphics to a smaller grid size and shoot it with a macro lens, in order that the pixel grid is sufficiently visible. Modern monitors can be really very high in resolution and the issue can be one of excessive subtlety - that is, it looks too good, the result is not sufficiently obvious.

 

Either way, macro.

 

P


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#3 Dominik Bauch

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Posted 26 June 2017 - 02:59 PM

Thanks for the info. So you'd essentially scale down the resolution until the moire goes away? I thought of this but was concerned that the number of pixels is still the same regardless of what resolution the monitor is set at so might not make a difference. I'll def give this a try.

Also r.e. macro lens; is this purely to get super close focus or are they better at handling moire. I realize that moire is a sensor issue but I suspect that glass definitely plays a role.


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#4 Phil Rhodes

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Posted 26 June 2017 - 03:02 PM

You shoot a smaller area of the screen.

 

Find an area which makes the pixels the size you want. Scale the graphics to fit.


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#5 David Mullen ASC

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Posted 26 June 2017 - 03:12 PM

Moire comes from the interaction of one grid pattern over another, so what changes the amount of moire is the relative size between two patterns. If the pattern is the same size, it doesn't matter if you shot it with a 35mm or 75mm other than if you are slightly less than dead flat-on or the wider-angle lens curves the sides, then focus fall-off or line bending will reduce the moire effect in those outer areas.

It's not the lens, it's the pattern interaction creating the moire. As Phil suggests, find a distance / shot size that doesn't moire and is within the borders of the screen and then size the graphics to what you want to see.
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#6 Dominik Bauch

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Posted 27 June 2017 - 05:49 PM

Played around today and off angles worked as but anything remotely flat on was infected. Just as you said. Still confusing as I've seen the front on shots in so many movies shot on Alexa.

Changing screen resolution unfortunately didn't have any effect other than making image more pixelated. 

 

I've been hearing that quality diopters like the Arri Master diopters or the Leica macrolux are amazing - virtually zero stop loss and no CA.

Any reason not to use those compared to a bonafide Macro lens? Seems like diopters are way easier as can be used on almost any lens with adaptors, also I really like what they can do for wide angle lens DOF.


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#7 David Mullen ASC

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Posted 28 June 2017 - 09:16 AM

A macro lens would generally be sharper but maybe in your case, some softness from a diopter would slightly reduce the moire problems.


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