During recent years, the Japanese company Zoom has more or less taken over the scene of audio recording for video production, at least when it comes to field and small scale studio productions. There are other companies producing suitable equipment, and some of that does sell as well, but Zoom has managed to line up a range of products that are just what most people need, at a proper price level and with a very high quality.
The range goes from the small H1 Handy Recorder, which actually can be used as a dictation machine but also works very well as the audio recorder in DSLR video recording setups. It is inexpensive, ultra-compact and versatile – you may see journalists hold it up when trying to catch everything being said at a press conference, concert guests holding it up to create a bootleg of the experience, or rock bands or classical orchestras recording their jam sessions or rehearsals – and the audio quality is suitable for production. The recorder has built-in stereo microphones and can have an external microphone attached as well. It records on micro-SD cards, each of them holding a day’s work of top quality sound. It is no wonder why this thing became so popular!
There are H2, H4, H5, and H6 Handy Recorders as well, each of them a bit more expensive and with more features, but also suitable for different scenarios. Some of them allowing for up to 6 tracks simultaneously recording and/or replacing the build-in microphones with a different type. And there are the iQ-products, which are microphones to put on top of iPhones and iPads so that they can be utilised as recorders. Just pick and choose what you need. Your audio tracks for your video recordings will in any case become a lot better than what is possible with just the DSLR audio recording facility.
Zoom also produces guitar effect pedals, which was their original main area of business, and they produce larger types of audio recorders with mixers (the R-series) as well as such things like a drum machine.
You can get a quick overview of some of the products and their price levels at Amazon’s selection of Zoom products.