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Moire issus with Alexa?


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#1 Dominik Bauch

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Posted 15 October 2016 - 06:20 PM

I shoot a lot of laptop screens and was thinking about getting an Alexa Mini.

Is the Alexa sensor prone to moire or is it a non issue. Red dragon can have issues with longer lenses. 

Anyone had any issues?


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#2 David Mullen ASC

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Posted 15 October 2016 - 08:34 PM

It's not a non-issue but it's not a big issue either.


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#3 Dominik Bauch

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Posted 15 October 2016 - 08:53 PM

Thanks David, would you say that it's on par or better than Epic Dragon? I was concerned that the lower resolution of the Alexa sensor would be more prone to moire than the 6k Dragon sensor.


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#4 Tyler Purcell

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Posted 15 October 2016 - 09:34 PM

Where it's true the higher resolution cameras have less of an issue, it's always an issue if you re-scale the image, either in camera or in post. I work mostly in post and I see moire issues constantly with re-scaled content that didn't exist in the high resolution camera original.

So yes it's nice to have a nice big high resolution imager, but distribution is still setup for 4k or below. This is why I vastly prefer the 3.2k of the Alexa with a an up-scaled 4k finish, rather then a 6k camera which is down-scaled to 4k.
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#5 David Mullen ASC

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Posted 16 October 2016 - 08:21 PM

Thanks David, would you say that it's on par or better than Epic Dragon? I was concerned that the lower resolution of the Alexa sensor would be more prone to moire than the 6k Dragon sensor.

 

 

I haven't compared them, but it's not just the resolution of the sensor, it's the optical low-pass filter that affects how much moire there is in the image.  Plus sometimes the moire isn't in the original, it's just appearing on your particular HD monitor that you are viewing on -- even film images can have moire problems when viewed on a monitor.  Red cameras have a fairly aggressive OLPF so moire isn't particularly a problem with them compared to a camera with no OLPF at all, like a BlackMagic camera.


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#6 Dominik Bauch

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Posted 17 October 2016 - 07:00 PM

Did a test today and from what I can tell the moire is far less of a problem than with epic dragon. I was able to shoot a macbook pro screen at on a wide open 135mm CP.2 at minimum foucs with no moire at all.

Pretty insane. I maxed out on the epic dragon at a 50mm, sometimes a 75mm would be good too but sometimes not. 


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#7 Robin R Probyn

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Posted 18 October 2016 - 05:59 AM

Moire also often depends what focal length you are on.. you can see this on a zoom.. a tiny bit wider or closer and the Moire will go..or appear..


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