Re: [TCML] Tesla Coil Video Problems

[Harvey Norris <harvich@xxxxxxxxx>]

--- On Fri, 12/25/09, gary350@xxxxxxxxxxxxx <gary350@xxxxxxxxxxxxx> wrote:

> From: gary350@xxxxxxxxxxxxx <gary350@xxxxxxxxxxxxx>
> Subject: [TCML] Tesla Coil Video Problems
> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> Date: Friday, December 25, 2009, 11:28 AM
> 
> I have tried several times to take video of the streamer
> from my TC but the sparks never show up.  I have tried
> different things, total darkness, slightly light, black back
> ground, streamers to targets, nothing works.  I can
> take still photos with my Nikon F camera on color film but
> the new electronic video camera will not show the
> sparks.  What is the deal with that???
It probably has to do with the sampling rate. This is the frames per sec. the recorder uses to make video. I am unsure about specs here but on the old style VHS camera tapes, you could look frame by frame on review in a single second, and you would count 60 of them, or 60 frames per second. When I purchased my JVC digital camera, I enquired about this sampling rate and I was told that it was 30/sec. Years ago the late Mark Metlica brought his large coil over and I filmed it on VHS which easily showed up on the VHS recording. But on VHS tape review one finds on frame per frame, this is mostly empty space, and the arcing itself consists only a small percentage of the total frames. Something interesting to do is to have video of both primary and secondary arcing, where we found that these were never simultaneous on the same frame. The fact that his  large coil operated at the lowest end of TC frequencies, I think he said it was in the 30 Khz range, this may
 have had something to do with the fact that the repetition rate of secondary arcing may have been relatively low compared to smaller TC's. But back then over 10 years ago, another idiosyncrasy was noted with VHS  tapings, that of the taping of oscilloscope beams, which would show a diagonal trace on the taping that was not there on what was being recorded itself. I was told that this was due to some kind of interference between the camera's frequency of operation and that of the scope beam. But with the newer digital camera, I have not seen this old effect. In the old days one could translate VHS tapings into a digital medium with the use of what was known as dazzle software, I dont know if folks use that anymore. But in the making of a recording of a rapidly blinking grounded neon I was hoping to find the No. of blinks/ second by making a VHS tape recording of it, and then on review of 60 frames in one sec I found 24 of them contained discharges. Now
 when the same recording was translated into digital that uses only 30 frames per sec as Dazzle software used, the recording looked totally different, and I think I counted that frames and found that now the information made by the recording was different. In fact I recently recorded this same blinking effect on my new digital camera, and found that the recording again looked very much different from the real thing. I was later able to find the exact frequency of this blinking by scope means. But here I am left wondering whether the old VHS camera, if it does give 60 frames/sec instead of the digital's 30 frames/sec, wouldnt the VHS camera then be better for making videos of TC secondary arc's, or is this really an issue, since many folks seem to be able to digitally capture TC arcs.
HDN
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