Real world 7D limitations

[Jonathan Betz]

Like many others, I have spent countless hours looking at test footage from the 7D and other video DSLRs recently. From what I have seen and read, these are some of the major video limitations:

1. rolling shutter
2. aliasing issues
3. h.264 codec
4. limited clip length
5. smaller crop factor than many interchangeable lens camcorders

I have seen the test videos showing problems with rolling shutter jellocam and aliasing problems, but I am wondering, are these limitations anything more than something for people to post Vimeo clips about and argue over in forums? For instance, I know rolling shutter is a problem if you are whipping the camera back and forth while filming, but is it ever a problem during more realistic use?

How much do these factors really affect the usability of 7D footage, and do people have experiences where the 7D limited their productions? How do these factors affect real-world, realistic shooting situations?

Thanks for the help!

[Bill Pryor]

Have you seen the complete short films that have been posted? That one documentary short about the festival in the Philippines looked good to me, shot in very real world conditions, bright sun, night shots with lots of motion, etc. There's lots of "measurebating" (Chris' word, but I wish I had said it first!) going on, as well as lots of people saying the codec is bad, though it looks pretty good to me, and I've edited H.264 footage in the past with no difficulties. Remember when HDV first came out--"You can't key it," "you can't edit it," "it has artifacts," etc. People have made feature films in HDV that look great. The great short that set the world on fire over the 5DMKII looked great. The camera is another tool. You don't just pick it up and shoot and overexpose and all that and expect it to look like a camera costing many thousands more. You have to learn to use it within its limitations, just as we learned to use HDV within its limitations. And all cameras and all formats have their limitations. I'm not saying this one is perfect, far from it, but a lot of the stuff I read on here seems overly defensive to me and mostly posted by people who own more expensive cameras that shoot other codecs, or haven't tried out the 7D. To quote the bard, "...methinks the lady doth protest too much." In my case, the tests I've done so far make it very useable in my real world. Maybe not for everything; I don't know that yet.

[Stephen Mick]

I've used the 7D now on two paying gigs, and know others who have as well. My experience has been this…

Rolling shutter is a non-issue in normal camera operation, but I also use Canon lenses with Image Stabilization for handheld shooting. I think this makes a big difference in the quality of the handheld shots, and pretty much eliminates rolling shutter issues.

I have yet to find a single shot ruined by aliasing. Yes, there are shots where I can see it, but it doesn't make the shots unusable for my needs.

People talk about the fact that h.264 is a delivery codec, not an acquisition one. I could care less. If it looks great, it looks great, and it doesn't matter to me how it was encoded. For my workflow, converting the original h.264 files to ProRes works like a charm.

The 12-minute clip length can be a pain, and of all the issues you've listed, this is, to me, the most significant. If you're shooting events, weddings, etc., it can be a deal-breaker. Most of what I shoot is outdoor/adventure films, and I shoot a bunch of interviews. The 12-minute limit just means I have to pay more attention to the camera during interviews, and to stop and start the camera more often than I'd like.

Crop factor is the biggest non-issue for me. With three lenses (11-16mm, 17-55mm and 70-200mm), I've pretty much covered the entire range of focal lengths I want, from super-wide to a pretty good telephoto.


At the end of the day, the quality of the footage is all that matters. My clients looked at footage from the EX1/HVX cameras and were impressed. The same clients saw the 7D footage and said, "wow." If it's good enough for my clients, it's good enough for me. Until the "next big thing" comes along.

--SM

[Jonathan Betz]

Thanks Stephen for all the information. That's exactly what I was looking for. As Bill suggested, I have wondered whether much of the negative hype about the 7D is just a result of keyboard-happy forum users wanting to criticize something.

I have seen many short films and clips taken with the 7D that looked great, but of course these filmmakers only include their best shots. It's good to hear from someone with experience with the camera that overall the issues are not too much of a problem.

[Chris Barcellos]

Jonathan:

What it is is people who have laid out $ 7k and more for HD cameras that are trying to convince themselves that you can't get decent video out of a $ 1,600 camera. I remember I felt the same way about the HV20 at $ 750.00 against my $ 3,200 FX1. I was wrong, and ended up owning one of those. No matter what you say, those nay sayers will say it can't be good. In the meantime, pro's and creative users will be adopting it, and using it for everything imaginable.

[Brian Boyko]

Originally Posted by Jonathan Betz

Like many others, I have spent countless hours looking at test footage from the 7D and other video DSLRs recently. From what I have seen and read, these are some of the major video limitations:

1. rolling shutter
2. aliasing issues
3. h.264 codec
4. limited clip length
5. smaller crop factor than many interchangeable lens camcorders

1) Rolling Shutter: If your subject is moving fast, it can be a problem; there are expensive, slow plug-ins to deal with post-processing corrections, but 99% of the time it's barely even noticed.

2) Aliasing issues: You'll pick up more moire patterns than usual, but shouldn't be too bad, and you can always "soften edges."

3) h.264 codec: At 48mbps, you're not going to see many artifacts. The problem with the 7D is that the type of H.264 codec does not have any "b" frames, which means that it's not as efficient as other codecs like AVCHD. So your 48mbps H.264 is probably only as clear as, say, a 35mbps AVCHD. That's still pretty damn good, especially compared to the previous standard of 24mbps HDV or 21mbps AVCHD. The other problem with H.264 is that older computers (and even some newer ones) will hesitate to display the files in that format. Intermediate files are needed - usually Apple ProRes for FCP or Cineform for Adobe/Sony workflows. I'm used to editing H.264 natively, however, and do so in Sony Vegas, which seems to have the best way of handling video.

4) Limited Clip Length: This is more a frustration than an actual problem. There's no good reason (well, actually there is A reason, but not a good one) that clip length is limited. If you are not sure WHEN the action will start, stop, and break, then this is a huge problem. I wouldn't use it for event videography, for example, unless you had a second, longer-running camera that you could cut to. (That's what I did with the Canon T1i covering a wedding.)

5) The 7D's sensor size is bigger than most camcorders, even those with interchangeable lenses, so this shouldn't be a problem.

Does the 7D limit people's productions? Absolutely; but I never use the 7D alone, I usually use it in conjunction with an HG20, which is a reliable workhorse of a camera. Picture's not as good but it does everything I need it to if the 7D's limitations cause me to lose a shot.

In narrative, where you can control the environment, the 7D's limitations shouldn't be much of one. But I'm doing documentary/event/videojournalism and the 7D is fine so far.

[Michael Rosenberger]

Originally Posted by Stephen Mick

I could care less. If it looks great, it looks great

Yup.

/thread

[Geoff Brandon]

Originally Posted by Brian Boyko

1)

3) h.264 codec: At 48mbps, you're not going to see many artifacts. The problem with the 7D is that the type of H.264 codec does not have any "b" frames, which means that it's not as efficient as other codecs like AVCHD. So your 48mbps H.264 is probably only as clear as, say, a 35mbps AVCHD. That's still pretty damn good, especially compared to the previous standard of 24mbps HDV or 21mbps AVCHD.

hmm..maybe im confused. When I took a FCP course a few months back, we went over framing, and If I remember right, when we were discussing h.264, I thought we were told the codec doesent have many I frames, which are the least compressible of all the frames, but make up the quality of the frame.
basically the h.264 looked something like this IBBBPIBBBBPI, etc, while avchd would like like this IBBPIBBPIBBPI


Anyone care to explain?

[Jon Fairhurst]

Codec standards define decoders. Encoders are not defined. Anything that can be decoded by a standard decoder is "legal".

h.264 encoders might "typically" insert a given number of P and B frames, but that's up to the encoder developer.

Personally, I'm not sure about the limits defined in h.264, nor have I analyzed a 5D or 7D stream, so I don't know the details for sure. I do know that their strategy is to do very simple encoding with lots of bits to keep the processing power (and heat and battery drain) low. For instance, h.264 allows sub-pixel motion estimation. No way are they doing that, as it's really processor and memory intensive. Non-real-time encoders and high-end broadcasting encoders can do those things, but not a real-time encoder in an HDSLR.