I'm sure we disagree about what constitutes aliasing. Most people think the only aliasing artifact is moiré, which I agree does not occur that often in real-world applications. But there are many other aliasing artifacts. I've been shooting my 5D2 for almost a year now, and with other 5D2 cameras in weddings and multi-cam shorts, and I've seen lots of footage posted online, but I have never yet seen one .MOV clip from a video DSLR that had both fine detail and no aliasing. Most of the time there is no fine detail because the DOF is too thin, focus was missed, subjection motion, soft lenses, diffraction, etc.

When I have stated that in the past, people are quick to defend the 5D2 and post many links to Vimeo that they say only has a "little" aliasing, here and there. In fact they are riddled with aliasing all over, but only have a little moiré, here and there. So it's obviously a difference in perception.

Here is one way to help illustrate the difference. The following image is riddled with aliasing artifacts, just like the 5D2:

http://thebrownings.name/photo/2009-...-400-point.png

And here is the same image, but with no aliasing artifacts:

http://thebrownings.name/photo/2009-...00-lanczos.png

Some people are not be able to see any difference between the two. Many would prefer the first image, describing it as sharp, crunchy, high microcontrast, with lots of fine detail, such as stubble. Others would see it as fake-looking, with harsh transitions, jagged edges, and lots of false detail, such as stubble that should be too small to see and jagged edges on the ear.

Some would prefer the second image, describing it as smooth, natural, with the appropriate amount of detail for its size. Others would see it as mushy, hazy, low contrast, and lacking in fine detail.

Which image do you prefer?

Can you see how that would result in a lot of miscommunication? When I say I dislike the first image very much because of aliasing, many people would respond by saying that they don't see any aliasing in it, and in fact they prefer the first image.

Others agree that there are indeed aliasing artifacts, but that you have to really pixel peep to see them, so the overall image is not affected. I highly disagree. To me, the aliasing causes the overall image to take on a very fake, computer-generated look. For me it's just as jarring as the difference between 24p and 60i: I notice the difference in the overall image, not just when pixel-peeping.

Agreed. Sometimes the low light and/or DOF advantages trump all else. Some scenes are so dark that my XH-A1 would not get a usable picture at all. When you compare an aliased image vs. no image at all, the aliased one wins every time. Furthermore, many audiences will prefer an aliased thin DOF image over a clean, high-res deep-DOF one. That's another good time for me to reach for my 5D2.

Good example. I'm sure many (most?) people actually prefer aliased images over anti-aliased, just as many people like the anamorphic artifacts. I like the oval bokeh and blue streaks.

It's not just specific little artifacts, it's the overall feel of the image. For example, say you ask someone to choose between two styles. The first is way oversharpened, oversaturated, over-contrasty (blown highlights, crushed shadows), heavy noise reduction, aliasing, and 60i. The other has low sharpening, neutral saturation, low contrast (no blown highlights or crushed blacks), no NR, anti-aliased, and 24p. Many people will highly prefer the first. That's why digicams are set out of the box to provide that kind of image: marketers know that it sells.

Your personal taste does not include a dislike of aliasing, and that's fine. So when aliasing occurs in your footage, it does not ruin it for you.

"Better" is subjective, even in the hands of skilled users. For some viewers, thin DOF and low light performance is the be-all end-all. For them it wouldn't matter if the 5D2 had banner ads embedded on the recorded video (somehow licensed so they could not be removed or hidden in post), they would still prefer it over cameras that had deep DOF, and would just assume that their audience will not mind the banner ads (perhaps correctly). For others, banner ads would be a deal-killer, no matter what the other benefits. To them, thin DOF is not worth the distracting banner ads.

In the same way, aliasing is distracting and jarring like banner ads. To them it is a much more difficult choice. One has thin DOF, low light, and terrible aliasing, whereas the other has deep DOF and no aliasing.

Agreed.

Agreed. Lots of top cinematographers, like David Mullen, prefer to shoot f/4 or f/5.6 on S35 whenever they can get a big enough lighting budget. That's equivalent to f/2 or f/2.8 on 2/3" and f/6.3 and f/9 on the 5D2.

I prefer the second image because it looks more natural BUT, and this is where our points of view differ, I don't consider the aliasing in the first image a show stopper at all. If you hadn't posted the second image, I'd find it difficult to even pick up on the artifacts unless I scrutinized it very closely.

Also, both images are 400x500 pixels in resolution (let's call this HD). If you now scaled the aliased image down to half that (let's call this SD) and back up again, it would end up looking a lot worse to me. Whereas you would probably find the aliased HD about as bad as the SD.

That's it in a nutshell. To some, the artifacts are no big deal at all, but to others, it's a very jarring difference, like 60i vs 24p.

I don't see that much aliasing with the 5DII. At least with sharpening turned down. The second image seems pretty soft for the 5DII.

Interesting. I think we have different perceptions of the same image. I'm curious what you think of the following comparison between the 5D2 and HV10:

http://www.dvinfo.net/forum/1132912-post31.html

The simple fact is that nobody is going to stop the video and look closely at a single frame when watching a movie - well, not 99% of the viewing public.

What matters most is how it looks when the footage is running, and when it is viewed at an average distance from the screen.

You have it backwards. If these were still images, aliasing would not be such a tremendous problem.

When you're looking at just one frame or a still image, the aliasing is actually not that bad. But when the footage is running, that's when aliasing goes nuclear!

Still frame:

• Aliased white specks in hair might be light glinting off hairspray.
• Jagged edges could be that way in real life.
• Stair-stepped lines could really have different widths.

Video in motion:

• White specks start dancing and popping, like fireflies in their hair.
• Jagged edges start flowing like waterfalls.
• Stair-stepped lines start changing width and popping in and out of visibility.

Aliasing in a still image is bad enough, but it is 100 times worse in motion.

100 times worse in motion? I had to laugh at that one :)

I'd also have to disagree with you on most points, Daniel, and more inclined to agree with Cris and Don.

Although tight registration is the issue you're concerned about, it's not those sorts of patterns you should be concerned about.

It's literally the threads of fabrics that are actually resolving on the camera's huge sensor. I know this because I see them in still shots where the focus is dead-on. But in video of the same exact lens/focal length/settings, the video moires.

The same goes for distant chain link fences, brick buildings or patterned roofs.

There are ways to hedge your bets, but they are all pretty experimental in nature at this point. I'm personally thinking about adding a softening filter for all shots. Still not sure exactly sure about which one....

While that's certainly true, the aliasing problems we're discussing are a little bit more obvious than that. I think any professional would find them objectionable.

I don't know that it's exactly 100 times worse, but Daniel is spot on here.

If you look at the first photo alone, you won't necessarily notice aliasing. Look at it side by side with the non-aliased photo, and you can find the aliasing, if you're looking for it. But this isn't reality. When somebody shows you a photo, they don't usually also show you the less crappy version to compare.

However, if the aliased image moves slowly, the over/under done highlights in the hair will start jumping around. They draw the eye - and you don't need a 2nd photo to find the problems.

So, yeah, aliasing is way worse with motion than stills.

That 5dII image looks pretty bad.

I do see a lot of aliasing in HD cable TV.

So how come we've seen all that beautiful footage from all those 5DMKII films if it's so bad?

There are plenty of shots that show zero aliasing. But when it sneaks in, you have to be ready to deal with it - often instantaneously. The quick fix is to defocus the shot slightly. This is a risky enough maneuver with the camera as the DOF can often be very shallow.

I find myself generally lighting and setting ISO to get the aperture somewhere around 5.6 in order to widen that focal plane a bit. That also will make more out of my zoom lenses - which are 2.8 L series glass. So, a nice side effect, that.

But it does make for harder-to-control aliasing. I'm still thinking a slight softening filter will help with various subjects. I need to get my hands on a few different densities and types to really test the theory, though... Anyone with a killer filter set want to report?

What type of optical low pass filter do these cameras have? There could be a mismatch between the stills requirement and the video.

First of all, the 5D2 has lots of good things going for it. Even if someone dislikes aliasing, those other things may be more important and/or make up for it. Second, there are lots of people who like aliasing, so for them it actually improves the image instead of making it worse.

Let me illustrate. The 5D2 allows control over the sharpening, contrast, and saturation. But imagine if it had no such control, but instead had all parameters cranked up to the top. For some people, that would be fine, they like the look of oversharpened, blown whites, crushed shadows, and hyper-saturated colors. Others would greatly dislike it.

I agree that there are plenty of shots that show zero moiré. And that there are plenty of shots that don't have enough fine detail to show aliasing. But I have seen very few shots that have both fine detail and zero aliasing. Probably part of the difference is that you and I may look at the same image and where I see aliasing, you might not see it. (Like the example image I posted above.)

Canon uses two layers of lab-grown, ground, and polished Lithium Niobate crystal, like so:

Sensor-Film: Low pass filter

They have been making the blur smaller, relative to pixel pitch, with newer cameras since the 30D. (That is, MTF curve of the OLPF has moved to the right, relative to Nyquist.) This has made aliasing in still images slightly worse.

Most certainly. The 30D OLPF was about right for my taste, but the newer cameras (50D) introduce a little too much aliasing even for stills, based on the results of Siemens Star tests. Of course, they are an order of magnitude too weak for row-skipping and binning 1080p video. Even for downsampled video they're too weak, but only by a few tens of percent in linear resolution.