Assessment of the 5D2 by the BBC (Alan Roberts) - Page 2 at DVinfo.net

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All about using the Canon 1D X, 6D, 5D Mk. IV / Mk. III / Mk. II D-SLR for 4K and HD video recording.


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Old September 4th, 2009, 04:15 PM   #16
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Originally Posted by Jon Fairhurst View Post
....................
BTW, if you can film an image of Princess Diana's ghost, the neither the Beeb nor any other news channel on the planet would care if it was shot on your kid's cell phone...
That's right - the rules apply unless the rules don't apply.

Canon's a bunch of engineers. They know these problems, and because of these issues probably underestimated the camera's impact. Another example of the big things being much more important than the details. The BBC will accept 35mm adapters on 1/3 cameras, which is rather pitiful compared to the 5DII.

We know Canon will come out with a much cleaner version of this technology. Thank goodness for Scarlet. On their own the Japanese companies would stretch this out for years.
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Old September 4th, 2009, 04:37 PM   #17
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It's funny though as the BBC will accept footage shot on a PD170 or a Z1 & to the best of my belief the 5d2 is better quality than both of those cameras.
In many ways it is better, but in some ways it is worse. For example, if you compare a 10-year-old computer with a small monitor and anti-aliased fonts, then compare it with a brand new computer with a large monitor and anti-aliased fonts, the new one will look much better. But what if the new one does not have anti-aliased fonts? Some people don't notice at all. But others are driven absolutely crazy by it.

Same thing with the PD170 and 5D2. The former at least has a natural anti-aliased look, even if it is low-res, low contrast, etc. The latter cannot achieve a natural-looking image if anything is in focus because it's riddled with aliasing artifacts. But again, most people don't mind (or even see) the aliasing artifacts. Some are driven nuts by it.

Furthermore, in the case of the BBC and this White Paper, the main problem cited is not the aliasing artifacts themselves. It's the compression artifacts *caused* by the aliasing. It can be helped greatly by having only a tiny sliver of the image in focus, but if you have any deep DOF shots (e.g. wide angle), the compression artifacts go crazy. They are bad enough already on the out-of-camera 5D2 files, but they get much worse when compressed again for broadcast.

Aliasing isn't really new with the 5D2. Before, people were adding aliasing artifacts in post (mostly on accident, but some of them did it on purpose because they like the "crunchy" look), but now it comes aliased out of the box.
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Old September 4th, 2009, 04:44 PM   #18
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I do think it's ridiculous to judge a cameras capabilities on this particular test, which does not clearly reflect the cameras performance in practice. As filmmakers we don't spend our time shooting resolution charts, how can this alone possibly represent our tools?
You may not notice the aliasing artifacts in your footage, but some do. There has been no 5D2 clip ever made that is both sharp and alias-free. It's either too soft (out of focus, diffraction, no small details, etc.) or it has aliasing.

The chart just allows more precise measurement of the artifacts. They do show up in real footage too.

Aliasing artifacts are explained in this metaphor. In real life, when you pour two liters of water into a one liter container, water spills out and makes a mess. But camera design is different: when you pour two liters of water into a one liter container, the water folds back on itself and corrupts the entire container. The amount of water is the level detail (spatial frequency), and the volume of the container is the number of megapixels in the camera. Aliasing is the corruption. Anti-aliasing filters reduce detail down to a level that can fit within the pixel resolution.

Aliases are a certain kind of image artifact; they can be described as jaggies, stair-stepping, unwanted sparkling, "snap to grid", wavy lines, bands, patterns, fringing, popping, strobing, noise, or false detail. Some photographers desire aliasing artifacts and describe them with positive terms such as ”crunchiness”, ”sharpness”, etc. Other photographers perceive the artifacts as an unnatural, unwelcome ”digital” look. The only aliasing artifact that is universally disliked by all photographers is moiré.

This image shows aliasing artifacts. Again, some people see no difference below. Others see "fake, digital, yuckiness" vs "natural and smooth":



This site has a great explanation of aliasing:

http://www.wfu.edu/~matthews/misc/DigPhotog/alias/

Aliasing is also described in this SD9 review:

http://www.imaging-resource.com/PRODS/SD9/SD9A12.HTM
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Old September 4th, 2009, 05:34 PM   #19
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To me this is just very useful information about how best to use this camera. I never had any illusion that it would not have some serious compromises.

Some remaining questions (to me):

1. Not good for use with heavy compression, but knowing exactly how much this effects something like DVD compression, which is much less than HDTV compression, would be useful. There might be optimizations possible.

2. How useful the technique mentioned in connection with some of the other cameras (softening the image slightly before it hits the sensor to lessen aliasing artifacts) might be with this camera. Even if it cannot make it suitable for heavy compression HDTV use, it may still be very useful for other uses.

3. The largest part of the problem seems to be from using de-bayering optimized for still use with moving images. I wonder if some sort of external software might be devised to partially 're-de-bayer' the images, if the original transform is known, and known camera settings are used. Plus, there is a programmer already mucking about in the cameras internal code, I wonder...

It looks like this cameras best technical use is actually the very thing people were most interested in - shots like closeups with very soft backgrounds. Not so bad.

-Mike
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Old September 4th, 2009, 05:39 PM   #20
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I am also wondering what things like pre-editing conversions might do to help or hinder-- things like Cineform's codec where the there changes to correct some luminance issues.
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Old September 4th, 2009, 06:32 PM   #21
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The keepers of the gates don't like your key.

Doesn't the BBC paper say the camera they tested is 29.97?
It's 30 true fps as far as I can tell.

Regardless... the 5Dmk2 is a really wonderful tool. I've shot with it twice now and can not believe what it's capable of for the price. And knowing that the EF L lenses are going to be usable on Scarlet (or RED should Scarlett never surface) and the 7D and whatever comes out next from Canon, I couldn't be happier.

Engineers can throw all the negative charts, graphs, papers, and blogposts at me that they like.

Ex: attached is a 5D capture from a video shoot from this past Sunday. I find it a bit more visually satisfying than the BBC's chart. If the aliasing artifacts bother you, I apologize.
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Assessment of the 5D2 by the BBC (Alan Roberts)-dreamincalifornian_fixed.jpg  
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Old September 5th, 2009, 04:05 AM   #22
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I believe the Z1 is an HDV camera that can shoot dvcam does this mean that the BBC doesn't accept it as HD even in it's HDV mode? Is that what you are saying?
Yes, quite a few broadcasters only allow a percentage (15%) of each HD programme's content to be shot with SD formats. Although, broadcasters will make exceptions if the subject matter makes sense, for example shooting with a Z1s on "Deadliest Catch", during which a large number of cameras get written off on each series.

The SD formats are listed on P4, which includes HDV.
http://www.bbc.co.uk/commissioning/p...d_delivery.pdf
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Old September 5th, 2009, 04:28 AM   #23
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Two years ago I found a previous paper that Alan Roberts wrote about the Sony A1 very helpful eg it gave useful guidance about the optimum exposure settings for this camera.

The moire test seems fair comment. Hardly anything I have shot with the 5DmkII so far has been free of aliasing and sometimes eg storefront shutters at night, it has been quite wild.

This camera is the first of a new generation. Within a year it will hopefully be made obsolete by new film cameras based on this technology.

Let's hope that Alan's paper helps to prod the engineers at Canon, Sony, Nikon etc into addressing the shortcomings of the technology.
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Old September 5th, 2009, 08:55 AM   #24
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I do think Alan's assessment is fair. I've encountered really bad aliasing on wide angle and highly detailed shots from the 5DmkII. Have a look at the buildings about a third of the way into this video One Week in Urumqi - Uighur ethnic unrest in western China on Vimeo

I am one of the news photographers that Canon originally aimed the 5DmkII at, indeed I was one of those calling for video on DSLR cameras for years. I think for news even the BBC will accept 5DmkII footage, its all about being there at the right place, right time. As the DSLR video thing has taken off the criteria changed and now many others want to use the camera for other uses. Canon didn't see this coming.

I do think it is only a matter of time before these issues are addressed, but for now we have to live with it.

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Old September 5th, 2009, 12:13 PM   #25
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I noticed the beautiful footage but had to look for the aliasing.

As far as Canon figuring out what to do with this huge interest in dslr video, I doubt they will make good choices. It crosses division lines in a large, conservative company. Canon does much better on the counter attack than leading the charge.

There's a chance, however, that they will get closer to matching red technically with the next 1 series. That's a technical challenge, not a product design and positioning decision.

Anyway, someone will exploit this new area.
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Old September 5th, 2009, 12:17 PM   #26
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I do think it is only a matter of time before these issues are addressed, but for now we have to live with it.
Agreed. Given that the Optical LPF in a DSLR is tuned for photos, and there are way more photosites than we need for video, it's just a matter of adding enough processing to do good 2D digital filtering. No new inventions or miracles needed.

Scarlet is 3K wide and is intended for 2K or 1080 output. It might have as much as 2.4K resolution.

The 5D2 is 5.6K wide. With better digital filtering, it should be capable of virtually perfect 1080p.

Given that silicon gets faster and cheaper all the time, it shouldn't take long.

Rolling shutter is the tougher nut to crack on large sensor cameras. To cut the skew by a factor of five, the chip has to get five times faster. The more sensible solution, IMHO, is to add another layer of transistors that will allow CMOS with a global shutter. That will take a few more years, unless RED has something up their sleeve that we don't know about yet...
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Old September 5th, 2009, 03:39 PM   #27
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I'll take FF35 with aliasing over claustrophobic 1/2" or 1/3" any day...

Why are the guidelines for broadcast video so strict? Most broadcast footage looks like crap anyways. People don't care about aliasing, especially on 20" SD televisions. Seems like a bunch of pompous BS...
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Old September 5th, 2009, 04:13 PM   #28
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Personally, I have had success removing aliasing by using Caprock Anti-Moire filters. They reduce the aliasing/moire without making any noticeable compromise on resolution. I can't completely get rid of the problem, but I can make it disappear in the rare occasions where it may be noticeable.
Interesting, I looked at their website and saw four variants: 4.0, 5.6, 8.0 and 11.0.
Which one do you recommend for the 5DMKII?
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Old September 5th, 2009, 04:41 PM   #29
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I'll take FF35 with aliasing over claustrophobic 1/2" or 1/3" any day...

Why are the guidelines for broadcast video so strict? Most broadcast footage looks like crap anyways. People don't care about aliasing, especially on 20" SD televisions. Seems like a bunch of pompous BS...
I think it's due to the degradation that takes place during transmission, meaning that any issues that are there in the original footage will be amplified when it's compressed and sent down the satelite.
I know lots of people that say that their HDV footage looks fabulous when camera plugged straight into HD TV set, but once broadcast it looks rubbish!
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Old September 5th, 2009, 04:58 PM   #30
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I noticed the beautiful footage but had to look for the aliasing.
I agree- I clicked on the link to look for objectionable aliasing, but ended up blown away by the beauty of the cinematography. Well done.
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