Capture cards are not necessary depending on what type of HD footage you intend to capture: compressed or uncompressed.
You can skip out on purchasing expensive capture cards when working with either DVCPRO HD or HDV footage because this type of footage is already compressed and can be captured through a regular firewire cable.
The only time you would need an HD capture card (and fast, large RAID drive) is when working with uncompressed footage or DVCPRO HD 1080 24P. DVCPRO HD can work in both 720p or 1080i, but if you want to make a movie that could be theatrically distributed (which the 24p format is best qualified for), you have to bring it into Final Cut as uncompressed HD video to work with it, and you don't enjoy real-time previews of many effects.
And as long as you don't want to send your final timeline out to an analogue tape you really have no need for a converter.
Capture Cards are also needed for use with other formats that cannot be captured by using a firewire cable: BetaSP, Digibeta, HDCAM, D5. Capture cards are also required for outputting to these formats.
Uncompressed digital HD video and audio can also travel down one easy HDMI cable connection, practically all new HD displays have HDMI support, and more and more camcorder manufacturers are including HDMI ports on their new HD models- with this you would need a capture card to get footage in and out of your computer.
Of course there are many types of cards and In/Out boxes. What type you need is determined by your general workflow... what you need to do with the various formats you work with.
Kona LH is among the best from AJA- not in the price range you?re looking for..
Black Magic Design?s Intensity Pro ? The Intensity is an extremely useful device for those producing HD content. While it's not quite as practical for capturing as FireWire, the option to take in the highest-quality uncompressed video is there if you need it. At just $249, Intensity could become an essential part of your HD arsenal.