I would like to start by saying "Ding Dong the switcher's Dead, Which ol' switch, the sequence switch!" In other words, you should take a serious look at dropping out of the market of selling switchers of any sort in systems of eight cameras or less. Systems of Eight cameras or more should be put into either a matrix system or dual multiplexers.
We have come into the time of the multiplexer and out of the days of the sequential switcher. Having said that, the first response is usually, ya, but Charlie, a multiplexer will cost anywhere from ten to thirty percent more.... my clients will never go for it. Bottom line, this is selling by cost. Let's look at the advantages of the multiplexer over the sequential switcher.
1. A sequential switcher must be played back through all of the cameras recorded. This can cause an extreme amount of time to just to find a little amount of recorded information. Additionally, the amount of time lose between recorded images from each camera can be great. Let's assume the average switching time between cameras is five seconds. In a four camera system, you would loose fifteen seconds of vital time going from camera one back to camera one. (assuming any recording speed)
Using a four position multiplexer, your lost time going from camera one back to camera one would be dependant upon the speed of the recorder. If using a time lapse recorder in the twenty four mode, you would be recording 1.25 pictures per camera per second. Therefore, your lost time from camera one back to camera one would be about 3/4 of one second. Secondly, since a multiplexer lays down a track of digital frame identification, you are able to play back any one of the four cameras only, all four in a quad format, or what ever you want. The advantage is considerably less lost time between cameras, extreme less lost time in review of tapes, enhanced information during playback, and higher options of review.
2. Multiplexers come in two, four, eight, and sixteen camera formats. Since these units are in actuality, high speed switchers, you are still using the same basic format of a sequential switcher. The advantage is that with a multiplexer, the recorder and multiplexer work together, keeping perfect pace between recorder speed and switching speed. Therefore, regardless of the speed of the recorder, you are always recording the exact same amount of information for each camera. This adds consistency to your data file.
At any rate, I hope I have convinced you to walk away from sequential switchers for good. They are antiques and need to be dropped out of our industry. Now for your second question.
If you want to calculate the number of pictures recorded by a time lapse recorder in any speed, the formula is simple. Take the speed of the recorder and divide by 120. The resulting number will be the amount of time (in seconds) that is lapsed between recorded frames. As example: A recorder in the 240 hour mode would record one picture each two seconds; 240 / 120 = 2 seconds lapsed time. A time lapse unit in the 24 hour mode will have a lapse time of .2 seconds or record five pictures per second.
Once you know this, calculating lost time between cameras or the number of pictures per camera per second or minute is simple... Just expand the formula. If you are using one of the newer 24 hour or 72 hour recorders, the calculation would be done differently. These units are designed to record a higher density of information per inch of tape and use a longer tape (T160). With these units, you only need to check the specification sheet and find out how many frames they record per second. Then back calculate to determine how much actual information that you will record.
