I have made a few short films and plan to get more serious about it, but professional digital video cameras are generally expensive and the recent line of beginner DSLRs which can take HD video like Canon 550D gets cheaper. I wonder what pros and cons of video DSLRs over traditional video cameras are and if I should buy a new DSLR for film-making if I have already had a DSLR (Nikon D50).
I tried to list the pros and cons in a vacuum (ie ignoring external factors). For example, handycams have much better mics than than dSLR's, however you have the option of using either a dedicated recording system, or a solid quality mic. So the mic is still a con, but it's easily mitigated.
- Access to awesome lens lineup
- Amazing low-light performance
- Use existing equipment, instead of separate video hardware
- Lighter travel
- Great performance for low cost compared to dedicated video cameras.
- AWESOME photo image quality
- Lens-based image stabilization
- build format (this can be a con as well)
- Familiarity with camera body
- In the right hands, with the right accessories, produces professional results.
- Depth of Field
- Huge image sensor
- Dedicated video cameras are designed for video
- Auto focus was very poor until dSLR video (and live view) started addressing this in 2014.
- clutched or "by wire" focus rings make follow focus impossible on many dSLR lenses.
- Video Format Support
- Video File Size
- 30 minute limit on clip length. This is an intentional limitation to distinguish the dSLR from true video camera, for import tarrif and tax purposes.
- doesn't incorporate sync signals for keeping multiple camera and audio recorders automatically lined up.
- Only flash media
- Sensor overuse causing heating issues
- built-in audio may be poor; early video-capable dSLR bodies did not make audio a priority. Some are just the same as camcorders now, but be sure to check for your camera model.
- very few bells and whistles for video. Since camera bodies are first and foremost for photography, most features are geared towards still photos (bracketing, AEB, etc). Features that you expect from a dedicated video camera (stereo mic, video outputs galore, jog-scrolling, enhanced playback features, dub over, etc) may not be present
- "Jello/Jelly" Motion Effect caused by the CMOS Sensor when panned quickly. Not all dSLR bodies exhibit this, and cheap camcorders do the same thing anyway.
- build format (this can be a pro as well)
I shoot video with two cameras, a Panasonic DVX100 (video camera) and a Canon T2i. I'll say that DSLR video looks great if you spend the time and effort but for ease of use a traditional video camera is leaps and bounds better.
The big differences are:
No autofocus with the DSLR. You can autofocus but you'll be waiting 4-5 seconds for it to hunt focus. Every decent video camera can autofocus in real-time. With a DSLR you'll be shelling out some change for a good follow focus (which can cost more than the camera in some cases!). You'll also have to convince a friend to pull focus if you're shooting with a fast lens.
XLR audio with the video camera. Nobody really uses any built-in mics on DSLR or video cameras for anything serious, so connecting a good mic is key. Every prosumer+ video camera gives you native XLR audio ports. DSLR's usually just have a stereo/mono 3.5mm jack and few options to balance/monitor audio. I know the Canon T2i even has auto-gain control which actually reduces audio quality!.
Jello with the DSLR. As much as this is talked about you have to try hard to get significant jelloing. It's something to think about but you'll quickly find the limits of your camera and it's easy to avoid.
Video cameras seem to have better image stabilization. Perhaps it's just me but even the midrange consumer camcorders have better IS than the lens-based IS from any of the Canon DSLR lenses.
Ergonomics and the other issues mentioned by the other answers are an issue but these are the biggest things I've noticed in the time I've been shooting.
DSLR video setups are more similar to traditional film camera, in the sense that you need to expose everything manually. It's very difficult to capture any action unless you have a dedicated focusing rig and someone to operate it. If you build all this stuff around a DSLR, you can get professional results, but if you just want to have one cameraman which can come with you and capture something that moves then video camera is still your best bet.