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Really excellent article. As a 5d owner, this is exactly what I really didn't want to believe, so thanks for laying out the incontrovertible evidence and forcing us all to face facts. It does make me want to find a good res chart and test it on the 5d, though I suspect its real resolution is only slightly better than the 7d.

The only chart I've seen on a 5D is that by Alan Roberts, during his assessment of the 5D for BBC HD use.
http://thebrownings.name/WHP034/pdf/...on_5D_DSLR.pdf

Barry, I think this article does a lot to quell the hatred you sometimes get (from fanboys, etc.).

The key for me is to point out that it may not matter to the user. For some, the picture looking good is all that matters, regardless of how it got there. It seems that for some people they need you "permission" to think that way. The usual conversation goes:

"This is what I'm seeing with tests: 500 lines of resolution"
"No! It looks so much nicer than my EX1, way more sharp!"
"Yes, it's tricking you, the EX1 resolves more lines"
"But...I like the way it looks"
"Okay, it's still not really sharper"
"Just tell me it's okay!"


I like that in this article you put more information about what the facts mean for the user.

Thanks. My intent with these articles is to point out what happens, so that folks can be prepared to combat or avoid troublesome scenarios, and will know the limitations that these new technologies provide.

Article has been updated with a couple of "real world" examples where aliasing contaminated and ruined shots, even in natural settings.

Actually, the 5d aliasing examples that you posted are quite mild. You should see some of the shots that don't get posted to vimeo. Twilight beach scenes are notorious.

On the other hand, the 5d can take twilight beach scenes that will knock your socks off, if you have the time to hit some shots and miss others. To my eye the 5d's rich color in low light is heads above any other prosumer camera (<$10k). So is its depth of field, of course. I don't agree that other cameras are equivalent "with proper lighting". Being able to shoot with less light opens up creative possibilities. What you call "proper lighting" is likely to be in my mind "the best compromise between the lighting I would prefer and the lighting the camera needs". Some cameras give you a wider range of lighting possibilities than others, and that's a definite advantage in terms of artistic range, and not just convenience.

You're absolutely right that all DSLRs have unprofessional sound, but that doesn't exclude them from professional use. It just means you need an external recorder. The internal audio is fine for home and most web video, and quite handy for manual syncing with external audio.

I also agree that it would be foolish to use a DSLR as primary video camera at a live event for a paying client. Unplanned situations force you to use a wide depth of field, which hugely increases the likelhood of moire, and nullifies one of the DSLR's main advantages.

However, you can do a very professional job with the 5d as primary camera for independent TV and cinematic work. It requires more pre-shooting and botches more shots than a pro crew and pro actors would tolerate, but for self-produced, no-budget projects, it's one of the best options. Still, it's probably best used in tandem with a standard videocam.

My wife and I have been shooting with the 5d for almost a year now, and I think we've run into just about every flaw it has. Until I read this article, I wasn't sure if some of these flaws were the result of aliasing or the codec, so thanks for solving that question and laying out the case in favor of aliasing being the primary culprit. But there's one more thing that I'm still unsure about.

To my eye, compared to conventional video, the 5d often looks flatter. By that I mean the 5d's image is somehow less convincing in producing the illusion of 3d. This is a very subjective judgment, and maybe others will disagree. But I'm wondering if that also could be a result of aliasing. Could aliased fake details be stomping on the subtle real details that give the illusion of depth?

I think that perhaps what you're seeing is that actually, even when sharply focussed, the 5D2 is quite soft. Resolution measures very low for a "1080p" camera, and standardly aggressive edge sharpening is applied. That means there's very little in the way of real micro-detail, and what is left gets squashed by the codec. I reckon that could quite easily account for the lack of "3d effect".

Thank you Barry for that great article. I'm a bit late on this discussion so I probably will repeat things that are already said. I own a 5D and I'm conscious of its limitations. But I always stated that I'm not too keen on sharpness. I sympathized for a long while with the HPX 500 and though we are talking about totally different cameras, I would say if you can live with a resolution of 720 lines (or less) the 500 and those video DSLRs are great tools. I really love their low light, DOF and color capacity - the only really ugly and distracting thing is aliasing and when one uses the now commonly known tricks one will get a pleasantly looking 720p image. Within one or two years we will have full HD resolution - but for me that is not the quantum leap that represented this first generation of video DSLRs, It's evolution. It is welcomed, of course, but is not a game changer anymore. Consider your video DSLR as a 720p camera and you will be happy. I am ;)

This is a great article Barry, and important info for folks to have if they're planning on working with these cameras.

You categorize the rolling shutter effect as being a kind of aliasing. That's the first time I've heard it described this way. The classic wagon-wheel example makes sense as aliasing — the sample rate is two low to accurately depict what's going on, rendering the impression of false information. But I'm not quite seeing how rolling shutter adheres to this definition.

So you threw me there at the beginning, but then you grabbed me right back again. I think I often confuse people when I write about the low effective resolution of the 5D and 7D, now I have a reference to point them to. Thanks!

-Stu

The idea with the "rolling shutter as aliasing" is that the slow sampling rate of the rolling shutter is not letting the system always accurately represent the information it's attempting to. Look at the "bendy propeller" and you might see how it's kind of the same situation as the wagon wheel, but driven by the slow progression of the rolling shutter down the frame. It misrepresents the propellor as actually being horizontal instead of vertical. It's a "motion" version of the res chart extraction I pulled out, where mainly horizontal lines are actually represented as primarily vertical lines. Might be a little bit of a stretch, but the main goal I was going for is that aliasing results in image (or sound or motion) representations that are not accurate. And the rolling shutter bendy propeller certainly did that.

I see rolling shutter as a seperate issue from aliasing. There is currently a passionate (perhaps even overly-passionate) discussion about LCD shutters over at Cinema5D with a member claiming that one is on the market in Paris for the 5D. There is also a vimeo of this kind of solution as proof-of-concept here:

http://www.vimeo.com/5976527

Aliasing remains for me an artifact of accentuation, whereas rolling shutter is the outcome of the slow reading-out of the sensor. Might be good to have a seperate article about rolling shutter if there isn't one already. (Come to think of it, I think there already is somewhere here...)