*** W. Curtiss Priest, Director, CITS Center for Information, Technology & Society 466 Pleasant St., Melrose, MA 02176 Voice: 781-662-4044 BMSLIB@MIT.EDU http://www.cybertrails.org Sony PowerShot A80 Using the Camera to Shoot Videos February 29, 2008 Introduction: With the availability of Internet video streaming sites such as YouTube.com and MySpace.com, it is became amateur video making has become increasingly popular. To create about one hour of videos for presentation at the Conference on Technology, Knowledge and Society, Northeastern University, Boston, USA, January 2008, for a presentation on "Knowledge Simplicity" (see http://object-one.blogspot.com) it seemed appropriate to use Internet-based media to help present ideas. As a short sample of using two finger puppets, in conversation, see: http://www.elearningspace.org/moles.wmv When I was a child, hand puppets were very popular. One television show called the Moppets had a feature puppet, Lamb Chop, created by Sherry Lewis. More history is easily Googled. I was surprised to find that very few retail stores carry hand puppets and I finally located a retailer of toys that carried some of the Folkmanis line of "Furry Folk and Folktails," see http://www.folkmanis.com So, this "technical note" is about two topics: 1. How to use the Sony PowerShot to shoot vidoes 2. Various video creation issues such as lighting and staging Using the PowerShot to create videos: There are three issues in using this camera for video. First, how do we keep it powered, and powered on? Second, how do we connect this to a PC and with what software? And, third, how do we handle sound? Part I: Sound At a prior conference I attended an informative presentation showing how to shoot videos using a camcorder. There was one fundamental rule -- do not use the camera's built-in microphone. So rule #1: use either a boom microphone or a lapel microphone. This eliminates the "hollow sound" characteristic of most amateur videos. The microphone should be only inches from the speaker's lips. Also, while a typical PC soundcard headset has a microphone that might be pinned under a sweater or hung with a boom, I have found the average "electret" condenser microphones to have too little volume, often making it necessary to place the microphone right at the lips. This usage is terrible, as, it picks up breathing sounds, etc. Professionals always use "Dynamic Microphones." These are moving coil constructed (like a speaker, backwards) and have low output impedance and low output signals. So to connect these to "line in" on a sound card requires both pre-amplification and impedance matching. If you Google this topic, you'll find both pre-amp circuits you can make (either from scratch or from a kit) and pre-amps for sale. As this is an "upscale market" for professionals, a pre-amp/mixer can be hundreds or thousands of dollars. One source of such a pre-amp is in a PA sound amplifier. Every auditorium, etc., has such an amplifier and handles both wired dynamic microphones and wireless microphones. Based on my Google search, one needs at least one low-noise, high performance "op-amp" between a dynamic microphone and "line in." In the case of my PA sound amplifier (a wonderous $5 yard sale item) there are four microphone inputs, accepting either a standard sized "phone plug" (huge compared with the mini-phone plugs used on sound cards) or the 3 pin Amphenol connector where signal ground and shield ground are separate (to prevent "current loop" hum). The "dual ultra low-noise, wideband, operational amplifier" was an NEC (micro)PC4570. The PA's "line out" is via an RCA phono jack labeled "Mix Bus." The mixer circuit employs two dual op-amps, the Rohm BA4558 (interchangeable with the TI TL092). For a while I worried that the pre-amp section was dead, until I found that there is an "out" "in" pair of jacks for external equalization, and, someone had slid the tiny switch from "Bypass" to "EQ." Thus, the sound only went as far as this switch. And, I instantly fried a five inch speaker I had on this 100 watt power amp., when I slid the switch and microphone feedback produced many watts of power to the speaker. As for "line" -- in the audio world "line" signals are always 600 ohms and signal levels are around 2 VAC (peak-to-peak). This relatively low impedance and relatively high signal levels make it possible to run "line" signals for hundreds of feet on shielded, low capacitance wire. However, in the PC world, both "line in" and "line out" (according to one Net source) vary considerably. The correct impedance can be upwards to 10,000 ohms, and signal levels are of many levels. As I've never seen a PC sound card (either onboard or via a slot) state the "line in" impedance, the only way to match this is by having a few audio transformers of differing impedances, and listening to the sound quality (and volume). "Line out" in the PC world often means "Speaker" (which typically range from 8 to 32 ohms impedance). And when "line out" requires external amplification (i.e., speakers with their own power source for their final amplifier stages), I haven't a clue what impedances to expect, and will simply say that all of this confusion results in poor sound quality on PCs. Part II: Powering the Sony Under a grey rubber plug is a power-in jack for the PowerShot. Embossed in the rubber is "DC IN." Embossed on the camera case is "DC IN 4.3V." Three immediate issues: what external adapter voltage? What adapter current? And, what polarity? The Sony manual has no information about any of this. Sony technical support could state the specs. for the separate adapter that they sell. And before I called, I determined that the power-in jack connected to the 4 "AA" batteries, plugging in a power plug simply switched those batteries out, and provide substitute power. Their "Compact Power Adapter" is CA-PS500. As the jack ground and the battery "negative" were joined, I could determine the polarity was "positive" on the center pin (often, but not always!). As the adapter only substituted for 4 x 1.5 VDC == 6 VDC, I tried a 6 Volt, 800 ma. universal adapter. The correct plug size was one of the eight that came with the universal. (While one places the correct polarity on the plug using an intermediate plug with a label, "Tip" -- I never trust that I'll get it right, and ALWAYS measure the voltage at the plug before I insert it.) Huh. While the current to the camera, when on, is about 300 ma., the current required when the current is turned on is over 1 ampere, as this is the time that the collapsable lens is extended by a motor. Indeed, Sony said the adapter is rated at 1.5 amp. Also, the 4.3 VDC lable is simply wrong. If you supply the camera with 4.3, the "low battery" light is always on, and, this indicator appears on top of the video. Fortunately I had a 5 VDC, 1.5 amp switcher adapter, and cobbled together two connector females to join with the right-angle power plug from the universal kit. Part III: Getting and Maintaining Video Out There are two ways to get video out of this camera. One way is to put it in "movie mode" and fill the flash CF card with the video. This has the advantage of being shot at the resolution you set for the camera, but, this fills up a 32 meg. flash card very quickly. One could hope that Sony, cleverly, brought video out the USB port, and that their photo-download program could capture that, but they didn't do that. The second way to get video (and sound) from the camera is via a cable supplied with the camera. This cable uses a "stereo"-style mini-phone plug and video is brought out as NTSC (or PAL) on one RCA jack, and audi is on the other RCA jack. Their supplied "AV Cable" is AVC-DC100. Video is on the yellow RCA plug. PC video capture cards accept NTSC (or PAL). I have an ATI VE Wonder tuner/capture card, and video displayed fine via a Video Player. Remember, we are not using the Sony's sound out, so, we don't plug the audio, black, plug into anything. Sound comes from our preferred source, directly into the PC's sound card. (Often, TV/capture cards have a short patch cord, just to bring TV sound out of the capture card and into the "line in" of the sound card.) But, before we get too excited about seeing NTSC video, we find that the unattended PowerShot, when left on, will "auto-power off." And, this "feature" only permits one to change "auto-off" from 20 seconds to 3 minutes, and does NOT permit the feature to be shut off. Can we keep the camera occupied without having to think about it? Fortunately, yes. If you keep the "DISP." button depressed, the camera will stay on indefinitely. So, to do this I took a plastic stand-off which accepted a 6-32 machine screw. We will attach this standoff, using the screw to a large elastic band which goes around the camera. So, my stand-off is 3/8" long. I used a rounded cutter bit in a Dremel and made a dimple on one end that matches the roundness of the DISP. button. I used a 1/4" long screw, going through a small hole I cut in the rubber band (mine is rubber-band that is 1/2" wide). Now, when the band is wrapped around the camera in the right position, the stand-off depresses DISP. Excess slack in the rubber band was taken up using a binder clip, sitting atop where the band passes over the "Mode Dial." The video out via the AV Cable is actually what normally appears on the LCD display. When you plug the cable in, that display goes dark, and the same display appears in your video player. And, the DISP. button has "3 positions." Press it once, the display comes on, press it again and the display is on with various video informational icons, press it again, and the display goes off. So, we first mount the camera on a tripod. We then supply the camera with external power. We have the strap around the camera. We press the "ON/OFF" button up top. Now, we can simply lift the screw/stand-off to walk the display button to the "position" where video appears with no icons! Leave the camera "Dial Mode" on "AUTO" (unless you don't want it adjusting focus, brightness, etc.) Now we can ignore the camera, and video is uninterrupted. PART IV: Recording clips The built-in Accessory for Windows XP -- MovieMaker -- is surprisingly easy to use. And, the software does both video/sound capture and permits "storyboarding" the clips. One does this by starting a "New" project. Once started, videos of indefinite length can be added to the project. One can then ask MovieMaker to display any clip, or, by placing these clips on a storyboard, the clips can be sequenced. MovieMaker will show video, in full screen mode, if desired. If you are wearing hand puppets, you get good at leaving the mouse positioned just over the "Record" button in MovieMaker. You then have one of the puppets press the left mouse button (and hurry back to the set). I found that getting an interesting background was important. I finally took a foamboard mounted scene of clouds, land and water (measures 4' x 3') and put that nearly vertically to the camera. I sat behind the camera/tripod, right up against it. There was about 2 feet from the camera to the background. I then stretched my arms from under, so that the puppets came up from below. I also had a matt black board as a "floor." Diffuse lighting was important. I had about half a dozen 150 watt flood lights positioned around the room. I also used a few desk lamps, but, it was important to check for lamp reflections off of the background board. The PowerShot handles low light conditions very well, but, remember that your "depth of field" gets narrower (more things will go out of focus) if you use too little light. (This is because the "f" of the camera goes down -- i.e., the "iris" opens more, and a larger iris means poorer depth of field.) MovieMaker provides minimalistic editing. A clip, moved to the storyboard, could have time clipped off from its beginning or from its end. I found the slider that did this fussy, and mostly accepted clips, ASIS. One approach produced poor results. As I needed script to talk from, I would put a sheet of Powerpoint like notes behind the puppets, against the background. I had printed these on white paper. To try to get visibility of these, I increasingly used zoom on the PowerShot. The result, particularly at low NTSC resolution, was that not only was even large font text fuzzy, but, as the screen filled with mostly white from the paper, the PowerShot darkened the clips, so the puppets increasingly became more like shadow figures.