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Canon EOS Crop Sensor for HD
APS-C sensor cameras including the 80D, 70D, 7D Mk. II, 7D, EOS M and Rebel models for HD video recording.


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Old April 2nd, 2011, 01:45 PM   #1
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Moire

So I just found out that 7D's and DSLR's in general create this terrible Moire effect and I'm wondering what you guys do to avoid / minimize this. When I was making my decision to switch from video cameras to DSLR's I never came across this issue for some reason. I know this has been a problem ever since DSLR's started to come out, (I found posts that talking about it back in 2009 etc) but isn't there a fix by now?

Here is my test footage (shot with a t2i but the 7D did the same thing). The roof and windows look so bad...

* I posted this in the general area of the board but wanted to talk to 7D user specifically as well.

Last edited by Oliver Darden; April 2nd, 2011 at 03:00 PM.
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Old April 2nd, 2011, 04:46 PM   #2
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Re: Moire

If I'm shooting wide I use the Sony EX1, the whole reason we use DSLR's is for shallow DOF, if you're not going to use shallow DOF use another camera that handles wide better, Moire basically happens when filming wide with little DOF - cameras are only tools with strengths & weaknesses.
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Old April 2nd, 2011, 05:48 PM   #3
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Re: Moire

Now that has to be one of the most balanced and sensible comments I have seen on the use of DSLRs in video production.
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Old April 2nd, 2011, 05:58 PM   #4
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Re: Moire

Quote:
Originally Posted by Nicholas de Kock View Post
Moire basically happens when filming wide with little DOF
Yeah, I just did some tests and noticed the same thing. Most of my shallow DOF shots are perfect; it's when everything is in focus and wide is when I see the Moire.
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Old April 3rd, 2011, 12:48 AM   #5
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Re: Moire

Be forewarned... It's not at all about shallow or deep DOF. It's about straight, regular, right-angle lines of any sort in the frame. A nice, tight headshot with crazy-shallow DOF... and someone wearing a houndstooth coat will still be moire-city.

The way that DSLR down-converts multi-mega-pixel stills to 2k video on the same sensor is a binning/down-convert process, and one of the side-effects is moire. Your best bet is to avoid brick walls, fences, patterned suits, and houndstooth jackets. The big bummer is that you won't notice the defect on your DLR screen or even your 7" field monitor sometimes. You pull up your footage on your big monitor... and see this crazy, show-stopping moire.

There is some rescue available in post... a little channel blur on the red channel and a feathered mask can save some shots. But, it's best to avoid moire in the first place.
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Old April 3rd, 2011, 02:34 AM   #6
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Re: Moire

Hey Brian, you ever tried the Caprock 2.0 Anti Moire Filter?

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Old April 3rd, 2011, 09:34 AM   #7
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Re: Moire

Thanks, Oliver, for the link. No, I haven't tried a Caprock filter, but have done some reading-up on them. They make several different "strengths" of filters, and each would be suited for certain focal lengths, types, and sizes of moire. While this might be This kind of extensive testing would take some time, and $, at $130 per filter.

I've also read that picture style profiles can be altered in terms of sharpness and contrast, to at least eliminate the rainbow artifacts (which, to my eye, are the most offensive), and this sounds like the most promising fix for me.
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Old April 3rd, 2011, 09:48 AM   #8
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Re: Moire

you might find some tests i did on this filter of some use. You have to compensate with sharpness and contrast in post.


As for color aliasing, my chart tests show that 5D handles color aliasing slightly better than 7D.
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Old April 3rd, 2011, 04:48 PM   #9
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Re: Moire

Here's a free Moire filter for FCP.

FCP Plugins Jorgen Escher
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Old April 3rd, 2011, 09:24 PM   #10
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Re: Moire

Ted, thanks for the test footage, very helpful. Seems the Caprock is a bit tricky to work with, but worth it if you can find the sweet spots for each filter.

Kirk, I tried the plug-in just now and it didn't really do anything. I had the Chroma Blur and Softening amount turned ALL the way up, and there was no noticeable difference. After further reading it seems this plug-in works best with micro-moire issues. The site says "This filter is less effective in removing moire appearing in regular and/or artificial patterns such as brick walls." Thanks for the lead tho, I'm sure there's something out there that can help.
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Old April 4th, 2011, 07:46 AM   #11
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Re: Moire

There is no way to prevent this with a Canon DSLR. Thats why they are so cheap compared to a pro video camera after all.

All cameras need a filter to prent this sort of thing. The filter on DSLR's is optimized to filter still images so they do not look too blurry. On HD cameras the filters are optimized for 1920x1080 video.

That is only part of the problem.

Canon has a rather disgusting method of down scaling the full sensor image to HD resolution. This is not a general DSLR issue because Panasonic does a much better job of this on their DSLR's.

Panasonic still has moire and aliasing but at a much lower level then the Canon DSLR's. This is mainly due to a lack of a HD resolution limited filter. The Panasonic AF100 is basically a DSLR with a 1920x1080 limited filter which is why it's video looks perfect.

The Panasonic DSLR's actually use a proper down scaling method which helps a lot but it still isn't perfect.

Basically with the Canon DSLR's this is something you have to live with. There will never be a fix for it other then Canon coming out with a new DSLR. Even if they do it still will never be perfect unless the limit the filtering to 1920x1080 which would in effect make stills look very soft.

A DSLR is not a 100% for a video camera and you should keep at least one video camera for shots a DSLR just cannot do very well.
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