Moire on many clothing tests with BMCC

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Stefan Markworth

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Moire on many clothing tests with BMCC

PostWed Mar 20, 2013 4:15 am

I have just doing several BMCC Moire tests to check various pieces of clothing for a short film we are shooting next week on Monday. When sharp, most of the clothing I tested suffer from Moire. While focusing on actors faces, clothes around the shoulders and neck have Moire. This is very disappointing. I am busy in pre-production, but as soon as I have time I will be posting examples of the video footage.

I know the BMCC does not have a OLPF. However this is just causing us more problems.

Does anyone know of any solutions to fixing the Moire problem on the BMCC, besides not being in focus. Has anyone found any very soft matte box diffusion filters, 4x4 or 4x5.65, that help keep a sharp enough image yet solve the Moire problem?

Has anyone tried or successfully used any Mosiac Engineering filters to work with a BMCC?

I would be very interested to hear how anyone using the BMCC on any serious professional productions solves this problem.

Moire is another problem to work around with the BMCC. I would be very grateful to hear from anyone who has been able to solve it.

Cheers,

Stefan
Stefan Markworth
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Trevor Zuck

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Re: Moire on many clothing tests with BMCC

PostWed Mar 20, 2013 5:00 am

Are you shooting RAW or ProRes?
Are you viewing at 100%
and was it under fluorescent lights?

Simple questions I know, but I've noticed moire more prevalent when viewing things not at full size. RAW gives you more definition to combat moire. And i've seen fluorescent lights cause weird image issues before.

Lastly i'd find a softer lens or just lower the clarity of the DNGs. or pick not so moire causing wardrobe.
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AdrianSierkowski

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Re: Moire on many clothing tests with BMCC

PostWed Mar 20, 2013 5:03 am

Not that I use the BMD-- yet-- but on the RED and other digital camera, when i hit such problems, I find a bit of a Tiffen Black Pro Mist to be the ticket. Or, if you wanna have a lot of fun, black net the lens.
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aesnakes

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Re: Moire on many clothing tests with BMCC

PostWed Mar 20, 2013 5:10 am

You can solve some moire in post, I believe someone made a plugin for the 5DMKII files in final cut

Here: http://colorbyjorg.wordpress.com/plugins/

In Nuke Ive been successful by converting from Linear colorspace to YCbCr, blurring the chroma channels (Cb, Cr) and then converting back to linear.

I have been successful getting rid of false color moire patterns but if its in course details you may still see it in the luminance like a chain link fence .

A filter to put in over the sensor would be ideal though.
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Steve Lee Jean

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Re: Moire on many clothing tests with BMCC

PostWed Mar 20, 2013 6:52 am

Ahhh, the wonderful moire. If it isn't so prevalent in your production, you COULD fix them in post frame by frame in a compositor like After Effects. Other than that, others had made fine suggestions. Many posters, including Marco Solario have indicated that its possible for a very sharp lens to worsen moire. There is the Zeiss Softar filter that Philip Bloom did a review on, though there are noticeable effects on the highlights.

Or.....You could always take the extra preventative measures as we have in the DSLR world. Change the wardrobe, work in a shallower DoF, try an alternative angle etc, if shooting outside sometimes a stop or two of ND helps if the moire isn't too bad.

Good luck!
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Thomas Schumacher

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Re: Moire on many clothing tests with BMCC

PostWed Mar 20, 2013 8:28 am

Here's a thread where they post some promising examples of removing moire with certain NR-methods:

http://www.bmcuser.com/showthread.php?2 ... -Solutions
https://www.gernemehrfilm.de/
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CaptainHook

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Re: Moire on many clothing tests with BMCC

PostWed Mar 20, 2013 11:39 am

I was going to post that link before but it's against the forum rules here to link to other forums.
**Any post by me prior to Aug 2014 was before i started working for Blackmagic**
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Thomas Schumacher

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Re: Moire on many clothing tests with BMCC

PostWed Mar 20, 2013 12:00 pm

CaptainHook wrote:I was going to post that link before but it's against the forum rules here to link to other forums.


What hilarious roule is that? So the admin has to do some work here.
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rick.lang

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Re: Moire on many clothing tests with BMCC

PostWed Mar 20, 2013 6:13 pm

Stefan Markworth wrote:I have just doing several BMCC Moire tests to check various pieces of clothing for a short film we are shooting next week on Monday. When sharp, most of the clothing I tested suffer from Moire. While focusing on actors faces, clothes around the shoulders and neck have Moire. This is very disappointing...
Stefan


If you have any wardrobe in your film that you can control, fix the problem at the source, not in post. I recall seeing an extensive test of different clothing materials on sensors and the results were that natural fibers particularly cotton were highly recommended and synthetic materials particularly rayons should be avoided. Sounds like an easy fix may be possible if your shirts and blouses can be made from natural fibers.

Rick Lang
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Felix Steinhardt

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Re: Moire on many clothing tests with BMCC

PostWed Mar 20, 2013 6:53 pm

What about Tiffen Digital Diffusion in 1/4 strength?
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Peter J. DeCrescenzo

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Re: Moire on many clothing tests with BMCC

PostWed Mar 20, 2013 8:20 pm

Felix Steinhardt wrote:What about Tiffen Digital Diffusion in 1/4 strength?


If it were that simple, Mosaic's anti-aliasing filters wouldn't exist. They don't have one yet for the BMCC, but I suspect they're probably working on one as fast as possible.
http://www.mosaicengineering.com
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CaptainHook

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Re: Moire on many clothing tests with BMCC

PostWed Mar 20, 2013 10:13 pm

gmf wrote:
CaptainHook wrote:I was going to post that link before but it's against the forum rules here to link to other forums.

What hilarious roule is that? So the admin has to do some work here.

This was forum Terry Frechette, one of the site admins (perhaps it's changed now):

We have a policy that we do not want to have URLs of resellers, sales and service companies and other forums in posts.
**Any post by me prior to Aug 2014 was before i started working for Blackmagic**
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Philip Sportel

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Re: Moire on many clothing tests with BMCC

PostThu Mar 21, 2013 2:29 pm

Distance from subject is a factor in moire as well. Try moving closer to or further from the subject and see if the problem disappears.
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Frank Glencairn

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Re: Moire on many clothing tests with BMCC

PostThu Mar 21, 2013 4:03 pm

Use vintage glass :mrgreen:
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I told you so :-)
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tom gray

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Re: Moire on many clothing tests with BMCC

PostWed May 22, 2013 5:04 pm

How can one get moire from a progressive scan, I only know of it happening from interlacing fields. it would appear these BM cameras are using interlace sensors and reassembling to look progressive. would explain data rates for such small cameras. when lines become too thin, and same size as the field the upper and lower can't decide which one should grab that same line and this is what moire is all about... in short that is! don't know how this can propagate from a true progressive sensor.
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Margus Voll

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Re: Moire on many clothing tests with BMCC

PostWed May 22, 2013 6:04 pm

Frank Glencairn wrote:Use vintage glass :mrgreen:



:D

Spot on!
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Scott Pultz

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Re: Moire on many clothing tests with BMCC

PostWed May 22, 2013 6:53 pm

tom gray wrote:How can one get moire from a progressive scan, I only know of it happening from interlacing fields. it would appear these BM cameras are using interlace sensors and reassembling to look progressive. would explain data rates for such small cameras. when lines become too thin, and same size as the field the upper and lower can't decide which one should grab that same line and this is what moire is all about... in short that is! don't know how this can propagate from a true progressive sensor.


Tom it is because of the bayer arrangement of the pixels. There is not an RGB value for each pixel location, but rather a single component at each pixel location:

RGRGRGRG
GBGBGBGB
RGRGRGRG
GBGBGBGB

When high frequency detail hits a sensor like this without properly being blurred first (low pass filter to cut the high frequency data), then moire/aliasing happens. It's a shame too because this is really the only issue with the BMCC image.
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Margus Voll

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Re: Moire on many clothing tests with BMCC

PostWed May 22, 2013 7:21 pm

Sometimes you do not want your image blurred and just use older lens or pro mist.
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Nick Vega

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Re: Moire on many clothing tests with BMCC

PostWed May 22, 2013 9:20 pm

Whats a good strength on the mist/softfx/digidiffusion filters for a wide lens and a 50?

I was thinking a 3/1 but idk if the crop factor would make a 1 too intense on a 50.
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Benton Collins

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Re: Moire on many clothing tests with BMCC

PostThu May 23, 2013 12:46 am

Philip Sportel wrote:Distance from subject is a factor in moire as well. Try moving closer to or further from the subject and see if the problem disappears.


This is very true. And moving the camera can be a simple fix.
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Michael Borkowski

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Re: Moire on many clothing tests with BMCC

PostThu May 23, 2013 1:00 am

Moire issues occurs at different focal wavelengths & the Best effective way to resolve moire issues
on any camera afflicted is to either Simply move in Or away or zoom in or out from the subject until the moire disappears or is minimized ,also if avail purchase an olpf for the camera. .....hope this helps
Cheers
http://www.synapsecreative.com.au/index.html
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Thomas Schumacher

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Re: Moire on many clothing tests with BMCC

PostThu May 23, 2013 4:54 am

If you can't move the camera, move the moire-causing object aka undress the talent! :mrgreen:
https://www.gernemehrfilm.de/
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rick.lang

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Re: Moire on many clothing tests with BMCC

PostThu May 23, 2013 4:08 pm

gmf wrote:If you can't move the camera, move the moire-causing object aka undress the talent! :mrgreen:


D'oh!

I think your creative idea was to 'remove' the moiré causing objects and I agree that would work! Of course the talent might prefer you 'replace' the moiré causing clothing.

Rick Lang
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Benton Collins

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Re: Moire on many clothing tests with BMCC

PostThu May 23, 2013 4:42 pm

Benton wrote:
Philip Sportel wrote:Distance from subject is a factor in moire as well. Try moving closer to or further from the subject and see if the problem disappears.


This is very true. And moving the camera can be a simple fix.


I should also add that zooming in or out will have the same effect.

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