Pixelation.... at DVinfo.net

Henrik Helms · January 15th, 2010, 10:51 AM

Hi!
I have experienced pixelation in hair and eyebrows in these interviews I have made with the Canon 7D.
I used the 20-70mm 2,8 Canon lens. It is shot in F4 and iso 400 - speed is set to 100 and the videomode is set to 720p50
Sharpness was put down two points and the same with contrast.
There is a link here - and it is possible to download the original.

What would change it? Lower the sharpness or???

By Henrik Helms On ExposureRoom

Paul Curtis · January 15th, 2010, 11:11 AM

Henrik,

I think you've just discovered how low the actual resolution of the 7D is. It skips lines on the sensor and the highlight on the glasses is a perfect example of the artefacts you'll see.

I think if you'd shot in 1080 and scaled down to 720 you'd have squeezed a bit more resolution out of the camera, perhaps enough to smooth over those highlights.

I've been researching these cameras and this is by far and away the worst aspect of them.

As far as fixing them, i'd be tempted to upres, blur it a tiny bit and scale down in something like after effects but it's unlikely you'll get a perfect result. I'm sure someone (if they haven't already) will come up with a filter that attempts to smooth these high contrast artefacts - much like the 4:2:0 reconstruction plug ins.

hth
paul

Jon Fairhurst · January 15th, 2010, 11:41 AM

Nah, the worst aspect is rolling shutter. Aliasing takes second place. ;)

Henrik Helms · January 15th, 2010, 12:00 PM

And heating...
Twice I have experienced that the camera signal problems with heating after doing interviews in 45 min......

Jon Fairhurst · January 15th, 2010, 12:55 PM

Thankfully, the 5D2 doesn't tend to suffer from overheating. I did see the temp warning once when the sun was hitting the LCD panel with the camera on a tripod. And loupes on the LCD can burn the thing, if the sun shines into it.

A piece of cloth to shield the camera from the sun is a good idea.

Bill Pryor · January 15th, 2010, 01:06 PM

I haven't seen any heating on the 7D either.

Andy Wilkinson · January 15th, 2010, 03:04 PM

Neither have I experienced any overheating issues with my 7D. I've seen the alaising and moire issue though (especially in 720p50 mode, big time).

Nothing's perfect (and if it was I could n't have afforded to buy it!). Use it for it's strengths, understand it's weaknesses. Most of all, have fun with it.

Paul Curtis · January 16th, 2010, 09:05 AM

Quote:

Originally Posted by Jon Fairhurst

Nah, the worst aspect is rolling shutter. Aliasing takes second place. ;)

Personally in most day to day shooting i don't think you really find rolling shutter issues unless of course you're running wild and hand held in which case grab a cam with a CCD sensor (LX3)

However you have resolution issues in most shots. I can live with rolling shutter but not the aliasing.

IMHO :)

paul

Jon Fairhurst · January 16th, 2010, 12:57 PM

To me, rolling shutter affects what and how one shoots. Handheld is out. Shoulder rigs are so-so. Tripods are good, but static. Jibs and dollies take setup time. Steadicams are expensive. Not to mention that strobe lights at a concert will destroy your footage.

And you will see those motion artifacts even scaled down for the web or in SD.

On the other hand, I've only had one truly unacceptable shot due to moire over the past year. Sure, I see aliasing on other shots, but most people say "that looks great!"

I'm not saying that aliasing isn't a problem - especially if you deliver at full res. But it doesn't change the way I shoot in the way that rolling shutter does.

Mikko Topponen · January 16th, 2010, 05:40 PM

YouTube - HMC Action Training 5 - Canon 7d

We shot that with the 7d. All hand-held and it works fine rolling shutter wise. The rolling shutter in 720p mode is actually way better than for example the rolling shutter on the hv20.

Paul Curtis · January 17th, 2010, 03:51 AM

Quote:

Originally Posted by Jon Fairhurst

To me, rolling shutter affects what and how one shoots. Handheld is out. Shoulder rigs are so-so. Tripods are good, but static. Jibs and dollies take setup time. Steadicams are expensive. Not to mention that strobe lights at a concert will destroy your footage.

I'm not saying that aliasing isn't a problem - especially if you deliver at full res. But it doesn't change the way I shoot in the way that rolling shutter does.

As you say it's entirely how you shoot and use these things. For me i do have a steadicam and tend to do less handheld and then i'm always in post where the resolution/aliasing issues could cause problems.

Although as Mikko pointed out and from what i've seen i believe the 7D is pretty good as far as the rolling shutter goes.

cheers
paul

Jon Fairhurst · January 17th, 2010, 11:47 AM

With a Steadicam I'm not surprised that aliasing would be the bigger problem. If you're using a wide-ish lens and setting the aperture/focus to give a forgiving DOF, that can lead to a lot that can alias. I'm building myself a steadi-rig to avoid rolling shutter and to make things more dynamic. Aliasing might soon be my biggest gripe too.

One solution is to narrow the DOF, but that requires a remote follow focus and operator. I've read some hints that some nice electronic focus aids will be available for EOS lenses before long. That's what I'm counting on. If nothing else, I'm hoping that Tramm will make Magic Lantern's eRack focus feature triggerable via IR in a future version.

January 15th, 2010, 10:51 AM	#1
Henrik Helms Regular Crew Join Date: Oct 2005 Location: Herning, Denmark Posts: 45	Pixelation.... Hi! I have experienced pixelation in hair and eyebrows in these interviews I have made with the Canon 7D. I used the 20-70mm 2,8 Canon lens. It is shot in F4 and iso 400 - speed is set to 100 and the videomode is set to 720p50 Sharpness was put down two points and the same with contrast. There is a link here - and it is possible to download the original. What would change it? Lower the sharpness or??? By Henrik Helms On ExposureRoom __________________ Greetings from Henrik dBA MEDIA www.dba-media.com

January 15th, 2010, 11:41 AM	#3
Jon Fairhurst Inner Circle Join Date: May 2006 Location: Camas, WA, USA Posts: 5,513	Nah, the worst aspect is rolling shutter. Aliasing takes second place. ;) __________________ Jon Fairhurst

January 15th, 2010, 12:00 PM	#4
Henrik Helms Regular Crew Join Date: Oct 2005 Location: Herning, Denmark Posts: 45	And heating... Twice I have experienced that the camera signal problems with heating after doing interviews in 45 min...... __________________ Greetings from Henrik dBA MEDIA www.dba-media.com

January 15th, 2010, 12:55 PM	#5
Jon Fairhurst Inner Circle Join Date: May 2006 Location: Camas, WA, USA Posts: 5,513	Thankfully, the 5D2 doesn't tend to suffer from overheating. I did see the temp warning once when the sun was hitting the LCD panel with the camera on a tripod. And loupes on the LCD can burn the thing, if the sun shines into it. A piece of cloth to shield the camera from the sun is a good idea. __________________ Jon Fairhurst

January 15th, 2010, 03:04 PM	#7
Andy Wilkinson Inner Circle Join Date: Sep 2007 Location: Cambridge UK Posts: 2,853	Neither have I experienced any overheating issues with my 7D. I've seen the alaising and moire issue though (especially in 720p50 mode, big time). Nothing's perfect (and if it was I could n't have afforded to buy it!). Use it for it's strengths, understand it's weaknesses. Most of all, have fun with it. __________________ Andy K Wilkinson - https://www.shootingimage.co.uk Cambridge (UK) Corporate Video Production

January 15th, 2010, 11:11 AM	#2
Paul Curtis Major Player Join Date: Mar 2005 Location: canterbury Posts: 411	Henrik, I think you've just discovered how low the actual resolution of the 7D is. It skips lines on the sensor and the highlight on the glasses is a perfect example of the artefacts you'll see. I think if you'd shot in 1080 and scaled down to 720 you'd have squeezed a bit more resolution out of the camera, perhaps enough to smooth over those highlights. I've been researching these cameras and this is by far and away the worst aspect of them. As far as fixing them, i'd be tempted to upres, blur it a tiny bit and scale down in something like after effects but it's unlikely you'll get a perfect result. I'm sure someone (if they haven't already) will come up with a filter that attempts to smooth these high contrast artefacts - much like the 4:2:0 reconstruction plug ins. hth paul

January 15th, 2010, 01:06 PM	#6
Bill Pryor Contributor Join Date: Jan 2003 Location: Kansas City, MO Posts: 4,449	I haven't seen any heating on the 7D either.

January 16th, 2010, 12:57 PM	#9
Jon Fairhurst Inner Circle Join Date: May 2006 Location: Camas, WA, USA Posts: 5,513	To me, rolling shutter affects what and how one shoots. Handheld is out. Shoulder rigs are so-so. Tripods are good, but static. Jibs and dollies take setup time. Steadicams are expensive. Not to mention that strobe lights at a concert will destroy your footage. And you will see those motion artifacts even scaled down for the web or in SD. On the other hand, I've only had one truly unacceptable shot due to moire over the past year. Sure, I see aliasing on other shots, but most people say "that looks great!" I'm not saying that aliasing isn't a problem - especially if you deliver at full res. But it doesn't change the way I shoot in the way that rolling shutter does. __________________ Jon Fairhurst

January 16th, 2010, 05:40 PM	#10
Mikko Topponen Regular Crew Join Date: Oct 2009 Location: helsinki Posts: 104	YouTube - HMC Action Training 5 - Canon 7d We shot that with the 7d. All hand-held and it works fine rolling shutter wise. The rolling shutter in 720p mode is actually way better than for example the rolling shutter on the hv20.

January 17th, 2010, 11:47 AM	#12
Jon Fairhurst Inner Circle Join Date: May 2006 Location: Camas, WA, USA Posts: 5,513	With a Steadicam I'm not surprised that aliasing would be the bigger problem. If you're using a wide-ish lens and setting the aperture/focus to give a forgiving DOF, that can lead to a lot that can alias. I'm building myself a steadi-rig to avoid rolling shutter and to make things more dynamic. Aliasing might soon be my biggest gripe too. One solution is to narrow the DOF, but that requires a remote follow focus and operator. I've read some hints that some nice electronic focus aids will be available for EOS lenses before long. That's what I'm counting on. If nothing else, I'm hoping that Tramm will make Magic Lantern's eRack focus feature triggerable via IR in a future version. __________________ Jon Fairhurst