Given the great deal of interest that has been expressed not only in the landmark film Slumdog Millionaire and its groundbreaking and technologically innovative director Danny Boyle, but also in the film's use of the Silicon Imaging SI-2K camera for some of the key shots in the film...
...it will probably come as no surprise that there has also been expressed some interest and questions about the rolling shutter employed by the camera and its ramifications for the film itself.
With those questions in mind, I will say the following: there are some rolling shutter artifacts that do appear in Slumdog Millionaire, and while I myself am one of those who tends to avoid the use of a rolling shutter in potentially troublesome situations, I am also one whose eye has been trained to a ridiculous degree to spot these sorts of things.
So while I will state that the rolling shutter does reveal itself in a couple of instances, I will also state the following even more loudly: The film won the Oscar for Best Freaking Picture. The point is, that those on the technical side may obsess on the minutia of a given shot or film sequence, while even the voters for the Academy will be forgiving if a sequence or film works emotionally. This does not mean that you should abandon sound filmmaking principles - it only means that a couple of rolling shutter artifacts in a feature-length film are not going to be what the audience goes home talking about if you have done your job as a filmmaker.
With that said, here are a couple of frame grabs from about one hour and forty minutes into the film, as our protagonist is in a car, trying to make his way through a throng of camera-wielding fans.
As you will know if you have read any of my musings on the rolling shutter, camera flashes present a specific problem for this method of image capture. As you can see, only a portion of the sensor was active for the miniscule moment in time when the flash was active. By the time the rest of the sensor had taken in the image, the flash was gone. Likewise, we have a partial exposure in the frame below.
So I guess it all boils down to this. Even the pros -- even the Best Picture Winner pros can get some partial exposure artifacts in their work. But before you freak out, ask yourself... Did you notice when you watched the movie? I highly doubt it. So while I don't want to talk you out of being a perfectionist in your filmmaking, do also realize that some things are more worthy of your finicky obsessions than others. I, for one, am glad that Danny Boyle didn't cut these shots from the film.
This particular piece of video was included in my lengthy post filled with footage of the Glidecam models, the Steadicam Merlin, and their combination with various cameras.
However, this clip warrants special note because of the interest users have been showing in the Sony EX1 and its rolling shutter.
Here, we see the Sony EX1 employed with the Glidecam 2000, and according to the notes on the clip, no stabilization vest or arm, etc.
This struck me as a situation where EX1 users and those considering one would want to know how the shutter performs.
Undoubtedly, many who have or may buy cameras in the $3000-7000 range will contemplate using it with a stabilizer in the Glidecam 2000-4000 / Steadicam Merlin range. As well, given the front-heavy design of the EX1, it is good that some people are out there testing its ability to be counterbalanced effectively.
Just for the hell of it, here is a brief DVinfo FORUM DISCUSSION on the Glidecam and the EX1.
Now that the Sony EX1 has been in the hands of the ambitious for a few months, it is being used for narrative storytelling and tales of these experiences are trickling in. With them come the wisdom of hands-on experience with the camera's ergonomics and real-world situational handling.
Below is a three-part diary of a six-day shoot with two EX1's. The entries discuss everything from lighting setups to supplemental equipment, from solutions for 24p flicker to sore thumbs.
First off, none of the commentary included here is meant to be insulting in any way toward the videographers who have produced any clips included in this post. In most cases, they have found some interesting settings and captured some nice imagery. They have simply, in this relatively early stage of the camera's release, tested the limitations of the camera's shutter mechanism and had this affect their footage to some (usually minor) degree.
That aside, now that we've seen some of the best, we can look at some of the footage that pops up in worst case scenarios.
The potential issues that can pop up are the kind of stuff that is scaring some people back to the HVX despite the superior resolution, lens, record times and chip size of the EX1.
Jellocam:
Now, I actually feel kind of bad even linking up to this particular bit of footage. It was filmed specifically to test the abilities of the camera, as I understand it. But the main issue with the footage is that it has had an aggressive smoothcam filter applied, which can create dynamic distortion of its own. The cameraman was running around handheld, trying to keep the camera steady barehanded, which is generally not a recipe for usable footage. Anyway, discount the effects you see by whatever factor you see reasonable for the smoothcam filter. I've had smoothcam warp and distort footage that was not shot with a rolling shutter. But anyway, here it is...
And don't let the rolling shutter and smoothcam completely detract from the fact that he found quite a nice setting and captured some otherwise very nice family footage. Damn rolling shutter!
Jellocam: These are not the WORST - They just show some Rolling Shutter Artifacts
Now, this following clip doesn't really belong in any "worst of the worst" list. They actually did a decent job with it and apparently won a contest with this clip. But what it does do is illustrate some more subtle Jellocam that can result from going handheld or run-n-gun with the EX1.
For some people, the Jellocam effect may not even be detectable here. For others, it may be intolerable when it pops up. Anyway, this is a bit more of a realistic illustration of what you might run into if you are simply doing your best with minimal filmmaking accessories and end up testing the rolling shutter's limitations.
Again, here's another clip that really shouldn't be in a "worst of the worst" post but more a "medium of the medium." It's another case of relatively subtle Jellocam that pops up in handheld footage and also when handheld in addition to the vibrations of a moving car. Once again, this may be barely detectable (if at all) to some, and a deal breaker to others.
The controversy that is popping up over whether rolling shutter effects are detectable with this camera in "normal use" is becoming fuel on some of the message boards that can often cause academic discussions about the properties of the camera to degenerate into a Panasonic vs. Sony Jihad that sometimes makes me wonder if I am reading educated opinions on videography or getting a unique glimpse into cult behavior. Either way, it seems to be a matter of personal taste and "wobble" threshold.
On the other hand, if you are going to be spending $7000 plus on your camera, you should not be doing the bulk of your "money shots" barehanded anyway...
The following link is to a clip under relatively challenging circumstances - handheld in a helicopter.
As you can see, the videographer caught some sweeping and stunning imagery from this position. On the whole, the CMOS chip seemed to hold up pretty well, though I can't say that there weren't ANY rolling shutter artifacts. Jello crept in a little from time to time.
Skew:
Here's an example of the skew you can get from side panning.
Bear in mind that in normal filmmaking, one typically would not pan back and forth this rapidly, and also, there would be some kind of compelling subject matter to draw focus away from the skew. Usually we don't film straight vertical lines for the sake of showing how they skew.
Here is some more Skew footage:
And finally, there is even a POST ON PHILIP BLOOM'S WEBSITE with a still capture of some pretty grotesque skew he obtained while whipping the camera around. That said, I can't say how noticeable or terrible the skew was in the context of the action he was filming.
Partial Exposure:
Here is a link to a clip where we see partial exposure due to the sirens on a cop car:
And Ned Soltz posted an EX1 CLIP AND SOME NOTES at the Dallas FCPUG site. The partial exposure effect in that clip is not a deal-breaker but it is worth noting its effect is mitigated by the fact that the point of division occurs on a white background (ice at a skating rink). So, if you are framing a shot where partial exposure is a risk, and you have any choice in the matter, a lighter background may be the way to go.
Finally, here is some rather nice footage that was captured on the EX1 of a fireworks display. As is characteristic of this camera, the image is sharp and clear. But in the later stages of the clip, some partial exposure issues do pop up. It's still a nice clip and the typical viewer might not even care, but there are some frames where the top half and bottom half are clearly divided in brightness.
Now finally, make a note here that the following footage is not from a Sony EX1. It was shot with an HG-10 and it can not be blamed on the Sony EX1. I only post it because it shows a fairly extreme example of Jellocam due to a rolling shutter. Around the three minute mark, shit really hits the fan, and that is just on a tripod with high winds.
Anyway, this does not necessarily represent how the EX1 would handle the situation. Even the high-end RED cameras, considered one of the great recent innovations of digital filmmaking, utilize a CMOS rolling shutter and suffer from some artifacts. But anyway, here's an extreme, just to be clear on what the phenomenon looks like. And bear in mind that this fellow did capture some fairly nice imagery, rolling shutter wobble vision notwithstanding.
You know what, I was going to save this for later in the discussion but let's just get this one out of the way.
As people delve deeper and deeper into these cameras, this one issue has become the keystone consideration and possible deal-breaker in their decision-making. So let's address it now. It's just one of the many things that will come into play decision-wise. But it's a biggy.
The EX-1, unlike its competitors here, utilizes a CMOS chip to capture its images. Now this is both good and bad.
The fact that the CMOS chip is more heat and energy efficient, allows it to be larger - 1/2 inch instead of 1/3. This means great resolution and low-light sensitivity, and the potential for a shallower depth of field. Not 35mm film depth of field, but something a little nicer than 1/3 allows.
Also, the CMOS chip avoids vertical banding when we hit bright light. If you have a camera with a CCD chip, point it at a bright light at night and you'll get vertical bright line from the top of the screen to the bottom. Banding. Gone with CMOS.
But...
All is not perfect in CMOS-land.
The way CMOS chips are designed, they use a rolling shutter, and this can lead to several problems when filming, especially when motion is involved.
While global shutters used with CCD chips take a single snapshot of what is in front of them with each frame - everything all at once - rolling shutters sequentially record the image in rows from top to bottom, one after the other, so that not all parts of the image are recorded at exactly the same time. Therefore, the subject being recorded may actually have moved a bit from when part of one frame is recorded to when another part of the same frame is recorded. This can distort the image.
When the EX1 came out, it was quickly hailed as the "HVX killer." That may or may not be, but many people's issues with the rolling shutter and the artifacts it creates are, at a minimum, keeping the HVX on some pretty strong life support.
Among the problems rolling shutter can create are:
Skew: The image bends diagonally in one direction or another as the camera or subject moves from one side to another, exposing different parts of the image at different times.
Jello-vision: This is most common in handheld shots. The rolling shutter causes the image to wobble unnnaturally and bizarrely. This typically only shows up in somewhat extreme circumstances, but we'll get into that later...
Partial Exposure: This one also sucks. If a camera flash goes off, it may only be present for some of the rows of pixels in a given frame. The top 1/3 of the picture may be brightly lit by a flash, while the bottom 2/3 of the picture is dark and unlit. The difference between the two parts of the frame can be very dramatic and even for a frame, is visible and jarring to the human eye. Similar problems can arise with police sirens, some flourescent lighting, and so on. That makes rolling shutters an issue for things like weddings, red carpet and event filming, and narrative filming situations that involve these issues.
Anyway, take a breather.
We'll get into some real-life examples and clips of the above phenomena in the next posts.
And don't go and eliminate the EX1 from consideration just because I opened with this issue. We're gonna cut rolling shutters apart a little bit, but we'll give this camera a chance to redeem itself.
Additional Links and Readings:
You can also find a good ARTICLE on the subject by Barry Green, an expert in digital video and also a strong proponent of the Panasonic HVX.
Here also is a POST by another video pro on blogspot that goes over CCD vs. CMOS. Tell him JC sent ya.
