By separating the mic from the camera, I should be able to position the mic for optimum sound while placing the camera for the visual effect I want. Of course, I can do this wihout an audio input on the camera by a technique called parallel recording, that is, recording on a separate audio system of some kind. The familiar clack of the slate at the start of a movie sequence is used to make it easy to synchronize the picture and sound, and this technique works very well for my homebrewed videos as well. Still it’s very tempting to think that recording directly to the camera is an easier way out, with camera audio every take and every edit lining up without any extra effort.

I’ve been interested in the range of options for attaching a mic to the Zi8, and back in December I went on a little mic shopping binge. Between my storage drawer, Ebay, and Sound Professionals I gathered a collection of mics in a range of prices. But I was struck with a glitch in my Zi8 audio, which required several round trips to attempt repair at the East Coast contract repair depot. Eventually Kodak agreed to replace my camera, but by then I was on a lovely trip to Hawai`i.

Test Design

Now that I’m back I’m ready to offer up some test clips. At first I planned to video a number of brief samples of guitar and vocal, which was very troubling to me. I strongly believe that audio sampling should be done with a single performance and carefully volume matched, in order to reduce the number of variables in the sample. As much as we think otherwise, humans just cannot judge subtle (or even not-so-subtle) differences without careful controls. My aha moment came when I realized that I was only testing audio, not video, so I could use a recorded source to get a repeatable performance. Focusing on audio only also allowed me to upload the much smaller audio clips, so the comparison will be quicker and easier.

For level matching I decided to take the easy way out and simply normalize the files. Normalizing raises the peak of a file to a given level, in this case I chose -3 dBFS. I adjusted levels like this so our ears won’t be fooled by level differences, but these samples hide the differences in the real recording you’ll get if you use one of these mics. So I’m including the original sample as well. Remember that I adjusted the sensitivity of the Zi8 for each mic, so the volume levels are affected by that even in the original, un-normalized samples.

I first created a test recording in Reaper, some slack key guitar naturally. I recorded in mono with an Audio Technica AT4050 in cardioid pattern. Then I added a bit of narration. All camera mics I know about, and many accessory mics as well, are omnidirectional. There are plenty of reasons why an omni is a good choice, but real trickery is required to get a good stereo image with omnis. So I threw in a bit of movement in the stereo field to evaluate channel separation. I arranged the narration and the stereo test ahead of the music and adjusted levels.

I placed all the mics very close to my normal listening position and played back the test recording through my normal monitoring chaing – Echo Audiofire 8, Hafler P3000, Dynaudio BM6p. A Radio Shack SPL meter showed 74 db C weighted at the mic position.

As I mentioned, I adjusted the sensitivity of the Zi8 for each mic. In each case I adjusted the sensitivity to the highest level that did not show any red. I label the default sensitivity as 0, lower sensitivity goes from -1 to -5 and higher goes from +1 to +5. I wound up using the whole range in this comparison.

Test Clips

Here’s the reference recording. It won’t get any cleaner than this.

or download ref.mp3

I used the Zoom H2 as the mic in my first experiments with the Zi8, so I included it in this comparison. It’s also handy because we can record with the H2 and the Zi8 at the same time. Even though the signal in the Zoom was very low and pumped up with a lot of digital gain in the normalization process, it is quite a bit cleaner than the Zi8. I set the Zoom to M Mic Gain because tests have shown that the H setting adds noise. This still resulted in a rather low level, so raising it also raised the noise as well.

or download h2p.mp3
Original versions, no normalization:

or download oh2p.mp3

I used the rear mics on the H2 so I could operate the controls on the front of the unit. As a result the stereo left and right are backwards in both the parallel clip and the Zi8 clip. Here’s the output of the H2 headphone jack recorded on the Zi8 with sensitivity set to -3.

or download h2v.mp3
Original versions, no normalization:

or download oh2v.mp3

If you’re like me you’ve been fooling with recorders for a while, maybe going back to cassette tapes. Perhaps, like me, you have some kind of little mic in a drawer somewhere. My drawer mic is labeled www.reactivesounds.com but the web site is a dead end now. I bought this to use with my minidisc recorder a few years ago. The mic is omni, no cable (requires an female to male extension), and has been repaired with superglue. I used -2 sensitivity for this mic.

or download drawer.mp3
Original versions, no normalization:

or download odrawer.mp3

I’ve used Sound Professionals http://www.soundprofessionals.com/ for these kinds of recording gear for years. I used one of their T-mics for years with my minidisc, but somehow lost it. They still sell a mic with the same model number, SPSM-1, but it doesn’t look much like the mic I remember. I set the Zi8 to -3 sensitivity for this mic.

or download spsm-1.mp3
Original versions, no normalization:

or download ospsm-1.mp3

The SPSM-15 is the least expensive single point stereo mic sold by Sound Professionals. It appears to have a higher low frequency cutoff than the SPSM-1, and/or lower sensitivity. As a result I set the Zi8 sensitivity to -2.

or download spsm-15.mp3
Original versions, no normalization:

or download ospsm-15.mp3

The AudioTechnica AT825 has been a popular single point stereo mic for many years, but was recently discontinued. The replacements are much higher in price, so it might be worth watching for used examples of the AT825 on Ebay or Craigslist. It seemed perfectly matched to the Zi8 and worked well at the default sensitivity setting.

or download at825.mp3
Original versions, no normalization:

or download oat825.mp3

I was impressed with the performance of the AT825. I was very disappointed in the AudioTechnica Pro 24. Although it looks much more impressive than the T-mics from Sound Professionals, it was very low in output, requiring that I set the Zi8 to the maximum +5 sensitivity.

or download atpro24.mp3
Original versions, no normalization:

or download oatpro24.mp3

Let’s Look at the Video

Let’s finish off with some actual video. Be careful with comparisons, but perhaps there will be some blatant differences we can take away. When I framed the shot to include the whole guitar the camera wound up about 5 feet from the instrument. I adjusted the Zi8 sensitivity for each mic using my normal procedure – the highest setting that did not show any red squares.

I had a little fun with my new Edius Neo 2.5 software putting together a compilation of the mic demonstrations.

All these mics sound better here than in the audio test with the recording, but they still show their basic characteristics. The camera mic picks up a lot more room, as it must at that distance. And since the room is a boxy little thing, the recording sounds small and boxy.

The H2 in this clip is very slightly overdriving the Zi8, to my ears. The slightly dark voice of the H2 comes through as well. The Sound Professionals SPSM-15 does a pretty decent job for very small bucks. I failed to mention in the video that the sensitivity on the Zi8 is down to -3. This means the SPSM-15 is quite sensitive, so it might be a problem if your source is loud. To my ear the AT825 is the winner. I like the clear presentation. I’m sorry I didn’t do a better job of balancing the channels.

I hope these comparisons are useful. I plan to try these mics with a different camera in a future post.

I’m pretty pleased with this new camcorder. Let’s look at the pros and cons:

It’s Pocketable

It’s compact. It’s right on the edge of being too big for a pocket camcorder, but I’d say it still works. Here’s a shot of the Zi8 next to a Motorola Razr:

Zi8 and Razr Side by Side

I’m embarrassed that I shipped my Flip Mino HD off to a friend before I did this comparison so I can’t show them side by side or show comparison videos.

Another factor that makes a good pocket cam is a low price, and the Zi8 does fine on that score. And while the user interface is a bit more complicated than the Flip or Vado cams, the Kodak has a bit more flexibility as well. The options are easily accessible with the control layout. It takes decent stills along with several video formats.

It’s Expandable

Compact Flash memory continues to ride the price curve down, down, down, so the ability of the Zi8 to use accessory cards lets the user take advantage of bargains when they appear. I often shoot a set of music that continues for an hour or longer. A 16 Gbyte SDHC card combined with the included AC adapter makes the Zi8 a great tool for my kind of shooting. For places where AC isn’t available, the battery in the Zi8 can be replaced with a fully charged spare.

The other big feature for my use is the stereo microphone input. When I shoot my solo guitar performance videos I usually record the sound separately, then synchronize the audio and video in post production. Recently I’ve been using a Sanyo Xacti HD2000 camcorder that has many great features including an audio input, so I’ve been able to record direct to the camera using high quality mics. The HD2000 is a just a little too bulky to be a true pocket cam, and it busts out of the “disposable” price range by quite a bit as well. Now with the Zi8 I have an affordable shooter that I can feed audio into.

The reason for needing an external mic is simple physics – the camera has to be some distance from the subject, but the microphone needs to be close to the subject, at least for the kind of stuff I do, recording solo acoustic guitar in less than optimal rooms.

Here’s a picture that gives an idea of the problem:

Zoom H2 audio into the Kodak Zi8 camcorder

The room in this picture is a screened lanai, or porch, in Kailua. Beautiful Kailua beach is about 50 yards away, so the surf is always audible in the background. The trade winds are usually blowing through the surrounding trees, and a fairly busy street goes by the back door. There’s no soundproofing or room treatment of any kind, so getting a decent sound is a challenge. Notice how far the camera is positioned from the guitar – 5 to 6 feet away. At this distance, the guitar is not very loud, while the surrounding waves, wind, and cars are quite obtrusive. But with the audio input in the Zi8, I can use the Zoom H2 as a stereo microphone, and place it about 1 foot from the guitar. Here the signal to noise ratio is much better.

But It’s Not Perfect

Naturally, the Zi8 has flaws, some minor, some a bit more troubling. I never thought about the flat bottom of the Flip Mino HD until I tried to position the Zi8 on a table without a stand. Oooopss. The Zi8 has a rounded bottom that requires some kind of support for any placement.

The feel of the Kodak is a bit flimsy compared to the Flip, but those flimsy bits give access to a replaceable battery and various connectors. The zoom capability seems like a bit of a joke to me, it works in digital mode so it impacts picture quality, and it operates in discrete steps that would be very distracting during a shot. The bundled Media Impressions software has a number of issues, judging by the discussions at the support forum but I was able to title and trim one clip with it.

**EDIT Nov 19, 2009**The italicized comment that follows talks about my problems with the AGC on the audio input, but I’ve since learned that there is no AGC. Ooops!! I must have been overloading the input pretty heavily. I plan to continue to explore the audio input in a future post.**End of EDIT**

The biggest negative issue for me is the AGC, automatic gain control, on the audio input. This function raises the gain when sounds are low, which raises the background noise. It also makes level setting more difficult. I don’t know if it’s possible, but I’m hoping for a firmware upgrade someday to turn off the AGC. In the meantime, I’ve come up with a setting that seems to get the job done, by setting the Zoom H2 to low sensitivity and turning down the audio sensitivity on the Zi8.

So How’s the Video?

As I mentioned at the beginning of this post I mentioned that I’ve done two video clips with the Zi8. Here’s the first one, shot in indoors daylight, an original composition I call Kui Lima:

and here’s one demonstrating the low light performance of the Zi8, an old song called Kalena Kai:

So that’s the story as I see it. For my particular application, shooting solo performer music videos, this little cam seems like a pretty good tool for the job. And like always in the fast moving world of consumer technology, we can look forward to the response this cam generates among competitors.