Moya,
There’s a major difference between a dedicated video camera and a DSLR. One is specifically designed to shoot video and the other is capable of shooting video. Now the gap between the two types is closing but the advantage of the DSLR’s at the pro level are lower cost, lower weight, a wide selection of interchangeable lenses and the ability to also shoot stunning photographs. If you need that capability, that’s probably the way you need to go.
However, for shooting video with a DSLR there are numerous shortcomings concerning image and audio controls that you don’t find with dedicated video cameras. To take full advantage of a DSLR’s cinema style video, you’re going to need a number of accessories that will come to a significant amount of money. The addition of these accessories will ultimately negate the initial advantages of lower cost and weight. Also, you’ll need a separate recorder to get clean audio with because the audio captured by DSLR’s is terrible at best and is best used for reference when syncing in post.
Lastly, there is a significant issue with DSLR’s overheating during continuous use that you don’t have with video cameras. Ultimately, it will come down to how much cash you have to throw at getting gear. No matter what you get, it’s never ‘just a camera’ you’re buying. You’ll need support gear (batteries, tripod, cases, blank media, etc.) and that stuff has to be considered in the cost of the camera purchase. Either choice has both it’s advantages and disadvantages. How hard they’ll work for or against you depends on your ability to take advantage of their capabilities.
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