Originally posted by and just read a review of the stereo mic saying the video mic would be better for general use since the stereo mic is not good at picking up sounds from a distance and the video mic is more directional and ignores sounds from the sides, focusing on what you are pointing your lens on. any comments to to that?
You need to understand the concept of Directivity Factor/Index. Take an omni-directional mic for comparison. This has virtually no directivity (although HF from the rear is reduced slightly). Say this mic is 10m from a musical instrument. By definition, it has a DF of 1.0. Now replace it with a cardioid. Because it is more directional we can move it back to 17m before it hears the same ratio of direct-to-reverberant sound as the omni does at 10m. We say it has a DF of 1.7, meaning it can be uses 70% further away and still have the same pickup balance as the omni. A super-cardioid, in this example, could be situated 19m away (DF 1.9), while a hyper-cardioid could be situated 20m away (DF 2.0)
All the mics mentioned in the previous paragraph should sound similar, with the same balance of direct-to-reverent sound. However, in reality the size of the mic capsule and the shape of the casing causes the mic to depart from the uniform directional pattern at both LF & HF. The more directional the mic, the more uneven the off-axis response. The general rule is that the more directional the mic, the more coloured it sounds.
Typical directional mics are not like zoom lens. They don't magnify the level of the desired sound. They reject the off-axis contribution more effectively. To actually "magnify" the direct sound you would need to use a mic mounted in a parabolic reflector, but the magnifications falls off at LF because a typical reflector is not big enough to reflect long wavelengths (LF). This is why a parabolic mic is OK for bird-song, but not for music recording.
The RØDE Stereo VideoMic is a cardioid (DF 1.7). The RØDE VideoMic has a super-cardioid capsule (DF 1.9) with a line gradient tube mounted in front of the capsule. This will boost the DF to somewhere between 2.5-3.0. RØDE does not publish a DF factor for this model and neither does any other manufacturer because of its variability against frequency. Short shotguns tend to be quite directional in the MF & HF, but not at LF. Long shotguns are a better, but are more expensive and too unwieldy to be practicable mounted on most cameras.
So yes, the RØDE VideoMic, in our example, could be used at 25-30m from the source compared to the Stereo VideoMic at 17m, but the StereoMic will sound better, particularly if you're recording violin or acoustic guitar rather than speech. And you lose a awful lot of the "life" & the feeling of "being there" when you go from stereo to mono. Say you have kids playing. You want to capture the life, the ambiance and and their movement in the soundfield, while hopefully reducing distracting sound sources (cars, airplanes etc.)
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BEST solution is to use either an omni (cleaner - no proximity effect - better resistance to wind noise) or a cardioid up close rather than mounted on the camera. The typical professional answer is to use a hyper-cardioid mounted on a boom up close. On-camera sound in rarely used, except in ENG (Electronic News Gathering) where it may not be possible to have a separate boom operator/soundman.
Dan.