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Moire pattern with Canon 7D

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Phil Yunker
Moire pattern with Canon 7D
on Jul 10, 2010 at 12:51:48 am

I shot some footage last week and on the side of the brick homes I got a really noisy moire pattern.
I was using a Canon 7D with a Canon 18-135mm F3.5 - 5.6 EFS IS lens, edited in FCP, compressed with compressor.
You can see the pattern here: http://vimeo.com/13047791
The original camera files had the moire pattern, so I do not think it's Apple's FCP, Compressor or Vimeo causing this.
What is causing this? Sub-par lens? incorrect picture profile? Camera compression with h.264, camera sensor, combination of all the above? How can I avoid this or is this the nature of the beast?
Thanks.
PHIL

moire pattern link here:
http://vimeo.com/13047791


PHIL YUNKER
Yunker Video Production Services
http://www.philyunker.com
http://www.linkedin.com/in/philyunker


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Noah Kadner
Re: Moire pattern with Canon 7D
on Jul 10, 2010 at 2:25:32 am

turn down your sharpness settings next time. But yeah Moire is an issue for these and a lot of cameras so don't fret too much. You just learn to spot situations that are not conducive to good looks.

Noah

Check out my book: RED: The Ultimate Guide to Using the Revolutionary Camera!
Unlock the secrets of 24p, HD and Final Cut Studio with Call Box Training. Featuring the Sony EX1 Guidebook, Panasonic HVX200, Canon EOS 5D Mark II and Canon 7D.
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Phil Yunker
Re: Moire pattern with Canon 7D
on Jul 10, 2010 at 2:31:07 am

Noah, thanks I'll try that.
PHIL



PHIL YUNKER
Yunker Video Production Services
http://www.philyunker.com
http://www.linkedin.com/in/philyunker


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Uli Plank
Re: Moire pattern with Canon 7D
on Jul 10, 2010 at 5:34:35 am

Moiré is unavoidable in DSLRs. You can't optimize the anti-aliasing filter for photography and video at the same time if the camera can't shoot 24 fps full-frame and downscale after that.

But due to the narrow DOF, you can keep repetitive patterns out of focus most of the time…

Director of the Institute of Media Research (IMF) at Braunschweig University of Arts


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Peter DeCrescenzo
Re: Moire pattern with Canon 7D
on Jul 10, 2010 at 4:00:45 pm

Uli is correct when he says "Moiré is unavoidable in DSLRs."

I'd just add as an FYI that the Panasonic Lumix GH1 hybrid "DSLR" produces noticeably less moire & alias artifacts in its HD video compared to Canon DSLRs. Further, Canon DSLR video moire/alias artifacts tend to include a color fringe smudge that GH1 HD video generally does not.

Don't get me wrong, the 7D is an excellent cam with many very important advantages over the GH1 (the 7D has far fewer compression artifacts in high-detail high-motion scenes, and live video output during recording!), but moire/alias artifact performance isn't one of them. ;-)

Barry Green wrote a very good & very fair article comparing the 7D & GH1 several months ago, before Vitaliy Kiselev's firmware hack became available for the GH1. Vitaliy's hack vastly improves the GH1's compression performance -- as good or better than 7D & 5DM2 HD video -- and also adds several other very useful features, some of which exist in a stock 7D:
http://www.dvxuser.com/articles/article.php/26
http://www.dvxuser.com/V6/showthread.php?t=206788


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Phil Yunker
Re: Moire pattern with Canon 7D
on Jul 10, 2010 at 4:19:14 pm

Peter, et al,
Thanks for all the info. What about the 5DMKII and it's moire compared to the 7D and Lumix GH1? Will the full size sensor be better, thus eliminating some of the moire? I have the 7D up for sale and wanted to buy the 5DMKII but will look at the Lumix GH1. Any know articles comparing the 5DMKII to the Lumix GH1?
Thanks.
PHIL


PHIL YUNKER
Yunker Video Production Services
http://www.philyunker.com
http://www.linkedin.com/in/philyunker


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Peter DeCrescenzo
Re: Moire pattern with Canon 7D
on Jul 10, 2010 at 4:54:57 pm

Actually, it's the other way around: The higher a DSLR's sensor resolution, the more moire/alias artifacts it tends to exhibit in HD video.

The optical low-pass filter in a DSLR is tuned for best performance for hi-res digital stills, not the relatively low-res of HD video. And the relatively low-performing (and relatively low-cost) HD processing & compression engines in current DSLRs also do their part to "mess up" the pretty images hitting their sensors.

Here are two comparisons/comparisons of the 5DM2 & GH1 ...
http://www.dvxuser.com/V6/showthread.php?t=214113
http://jayshaffervideo.com/why-the-hacked-panasonic-gh1-is-a-better-video-c...

... but most posts I've seen from people who own both the GH1 & 5DM2 say they _love_ their 5DM2: Its super ultra narrow DOF & low light shooting capability can't be matched by the GH1. However, for most productions a full-frame DSLR's narrow DOF can be a hindrance since it makes pulling focus a significant challenge. And a GH1 fitted with a fast lens, and especially together with Vitaliy Kiselev's firmware mod, can give a 5DM2 a run for its money.

Compared to the most common 35mm motion picture film format, the crop factor of the GH1 is 1.18, a more useful comparison for video producers than the more oft-quoted 2.0 crop factor when compared to the 35mm still photography format.
http://www.dvxuser.com/V6/showpost.php?p=2005971&postcount=105

For most productions the differences aren't an issue, but obviously there are exceptions. Certainly, when you need its "look", the 5DM2 is a great choice.

Then again, there's the ease and relative low cost of fitting lenses to the GH1, including even cine PL lenses, without permanently altering the cam or spending many many thousands just for the hardware mod:
http://www.hotrodcameras.com/
http://cameraquest.com/adp_micro_43.htm
http://www.fotodiox.com/catalog/index.php?cPath=21_101

Until something new is announced out at Photokina this Sept. ;-)


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John Frey
GH1 firmware hack
on Jul 10, 2010 at 5:08:53 pm

Peter, I have not yet installed the latest hack for my 2 GH1 cameras. Have you had any major issues - freezes, etc. Which settings would you recommend for both 1080 24p and for 720 60p. I am starting on the 2nd part of a motorcycle racing 'slo mo' project, and the 720 60p looks like the right choice. Are you able to use SDHC class 6 cards successfully with the new settings? Can you comment on 16 GB card capacity comparing the default Panasonic 60p setting vs. the hack! Any info that you can share would be greatly appreciated, as I am considering the firmware hack install this weekend.

John D. Frey
25 Year owner/operator of two California-based production studios.

Digital West Video Productions of San Luis Obispo and Inland Images of Lake Elsinore


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Peter DeCrescenzo
Re: GH1 firmware hack
on Jul 10, 2010 at 5:27:16 pm

Hi John: I've added firmware mod-related notes to my sample GH1 video clips on Vimeo; for example:
http://www.vimeo.com/12969418

One thing I can add here that isn't discussed there: I haven't done much 720p shooting with my GH1, so I can't comment on that. I've mostly been shooting AVCHD 1080p24N with the firmware mod's official "C" settings.

In summary, if you plan to shoot using the firmware mod's 24pN mode (w/o pulldown), then use a very fast Class 10 SDHC card (such as Sandisk Extreme Class 10) to increase the odds of recording without issues.

Counter-intuitively, if you keep the cam and/or scene moving and/or use selective DOF focus you can use somewhat slower Class 10 or 6 cards. Currently, with the firmware mod AVCHD 1080p24N produces very high data-rate spikes on _static_ high-detail scenes. I'm using a Panasonic Class 10 SDHC card successfully to shoot ~95% of typical scene w/o issues. Worst case, if I can't shoot the scene differently in terms of motion or selective focus I can temporarily re-flash the cam's firmware so it records pulldown just for the "problematic" scenes.

As always, since YMMV, you should run end-to-end tests before production day.

See also the earlier thread here:
http://forums.creativecow.net/readpost/280/2071

Anyway, sorry to hijack the OP's thread.


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Phil Yunker
Re: GH1 firmware hack
on Jul 10, 2010 at 5:35:17 pm



[Peter DeCrescenzo] "Anyway, sorry to hijack the OP's thread."

That's all useful information.

PHIL



PHIL YUNKER
Yunker Video Production Services
http://www.philyunker.com
http://www.linkedin.com/in/philyunker


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Phil Yunker
Re: Moire pattern with Canon 7D
on Jul 10, 2010 at 5:33:08 pm

[Peter DeCrescenzo] "The higher a DSLR's sensor resolution, the more moire/alias artifacts it tends to exhibit in HD video. "

Well that makes perfect sense, not what I want to hear, but makes sense.
Thanks for the links I will have to read these later this weekend and look into the GH1.
And get out this week and shoot some more with the 7D with the sharpness dialed down a bit and see what happens.
Thanks.
PHIL


PHIL YUNKER
Yunker Video Production Services
http://www.philyunker.com
http://www.linkedin.com/in/philyunker


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John Frey
Re: Moire pattern with Canon 7D
on Jul 10, 2010 at 6:01:37 pm

Phil, here is a link to a GH1 Hack tester with brick walls and tiles. Very impressive.

http://www.vimeo.com/12792325

John D. Frey
25 Year owner/operator of two California-based production studios.

Digital West Video Productions of San Luis Obispo and Inland Images of Lake Elsinore


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Phil Yunker
Re: Moire pattern with Canon 7D
on Jul 10, 2010 at 6:11:41 pm

Bricks and tile roof look good, no moire.
W.A. is a very cool place, btw.
PHIL

PHIL YUNKER
Yunker Video Production Services
http://www.philyunker.com
http://www.linkedin.com/in/philyunker


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Phil Yunker
Re: Moire pattern with Canon 7D
on Jul 10, 2010 at 5:50:43 pm

[Noah Kadner] "turn down your sharpness settings"
So I'm looking at my picture style settings and I have the sharpness dialed to just one click from zero or all the way down. Same with Contrast, Sat is @ one to the left from center and colour tone is at zero.
You think dialing the sharpness all the way to zero?
Thanks.

PHIL





PHIL YUNKER
Yunker Video Production Services
http://www.philyunker.com
http://www.linkedin.com/in/philyunker


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Uli Plank
Re: Moire pattern with Canon 7D
on Jul 11, 2010 at 11:26:35 am

Yes, I'd always dial sharpening down to zero, it doesn't do any good. You can always add some sharpening after grading, noise reduction etc. and use more sophisticated and fine-tuneable methods for that.

There's good reason for RED not to have any in camera sharpening. It's not bad per se, but you'll want full control. The only place where it would make sense is video to be used without much post-processing at all. But that's not what you'd get a DSLR for, that's the domain of a video camcorder.

All other settings are highly dependent on your set, lighting and desired look. You need to get as close to desired look in camera as possible, since the massive compression together with 8 bit doesn't leave too much room for grading – you images can fall apart quite easily. For example, I don't subscribe to the idea of always shooting flat as sometimes suggested. If you need some punch later, you'll have to stretch those few bits too much. Of course it makes sense with very high-contrast scenes, since the sensor can do much more than 8 bit.

Director of the Institute of Media Research (IMF) at Braunschweig University of Arts


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Phil Yunker
Re: Moire pattern with Canon 7D
on Jul 11, 2010 at 2:55:56 pm

Uli,
All great info and makes perfect sense to me. I was told to shoot flat and then grad it in post. But your advice on getting it close to your desired look in camera makes sense as well.
Thanks again for all the advice.

PHIL

PHIL YUNKER
Yunker Video Production Services
http://www.philyunker.com
http://www.linkedin.com/in/philyunker


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