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Re: [TCML] Tesla Coil Video Problems with example video
Gary -
There are at least two different problems that are commonly encountered in recording Tesla coil streamers on video cameras:
1. The auto focus system cannot achieve focus on the transient, rapidly-moving arcs;
2. The autoexposure system cannot determine the appropriate exposure, because of the transient, very high contrast nature of the arcs, especially with a dead-black background.
For the focus problem, see if your camera has a "manual focus" or "focus lock" mode. If so, set (or lock) the focus at a point slightly in front of the topload. (Search "hyperfocal distance" for more details.)
The exposure problem can be a little bit more difficult to deal with. The easiest solution is to provide some level of illumination for the Tesla coil AND the background that is bright enough to allow the camera's autoexposure system to function, but still dim enough to see the discharges clearly. It usually doesn't take very much background illumination to keep the autoexposure system functioning. Some cameras will have an "exposure compensation" function that allows you to bias the exposure level + or - a few stops; experiment with it to see how it affects exposure.
Alternatively, if the camera has an "exposure lock" function, try setting the exposure lock while the camera is pointing at different levels of background illumination, and then recording the Tesla coil discharges. This is a trial-and-error proposition, but you may find one particular level of background illumination that, when "locked in" to the camera's metering system, gives good results.
If the camera is extremely "basic" and does not offer any focus or exposure controls, your only option is to try illuminating the coil with some light level and hope that the camera's autofocus and autoexposure can cope.
Personally, I find that illuminating the coil with a low level of lighting gives the best results with both the autoexposure and autofocus systems, and gives the best overall visual effects. For some reason many Tesla coils are videotaped in complete darkness, where the streamers just seem to appear from nowhere against a dead-black background, and you can't see any details of the Tesla coil itself, or get any idea of the actual length of the streamers. I find it much more interesting when the entire coil itself can be seem, even if dimly, and streamer length can be gauged. If you are running a spark-gap coil, it is important to completely optically shield the spark gap so none of the light from the plasma shows up in the image, or reflects off nearby objects. If not, it is extremely distracting as the spark-gap plasma is much brighter that the streamers, and the light is so intense that it causes all sorts of strange visual artifacts due to saturating
the CCD or CMOS detectors in the camera (like columns of bright vertical dots, etc), or "flare" due to reflections from surfaces within the camera lens.
Regards,
Herr Zapp
--- On Sat, 12/26/09, gary350@xxxxxxxxxxxxx <gary350@xxxxxxxxxxxxx> wrote:
From: gary350@xxxxxxxxxxxxx <gary350@xxxxxxxxxxxxx>
Subject: Re: [TCML] Tesla Coil Video Problems with example video
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Date: Saturday, December 26, 2009, 4:13 AM
I have no problem taking photos with Kodak film or Fuji film with my old Nikon F camera. My problem is this Kodak Easy Share C643 electronic camera that takes photos and video. I can take video and upload it to You Tube.. It has 3 settings for video and photo quality set at low quality video is good and I get 6 minutes of video time. If I change to medium quality I get 4 minutes of video time and at high quality I get 2 minutes of video time. There is no shutter speed on the camera at least I have not seen it listed in the instructions. I have noticed taking regulate photos and video the camera needs light to properly focus to take a clear picture and video. Maybe trying to take pictures of TC sparks in the dark or low light is not letting the focus do its thing and auto adjust. Maybe I should be taking TC pic with the lights on I have not tried that yet. I'm not sure the sparks can be seen with the lights on so that would be much
different than the problem I have now the sparks are not showing up when taken in the dark. Check out the pics as you can see the camera takes good video and good pics of normal stuff I just can not figure out how to get a good video of my Tesla Coils sparks.
Here are some example of video I have done. No problem here.
Water fall. http://www.youtube.com/user/Lowracerman#p/u/10/d4DD7U3XTvk
6 cylinder radial engine that I built. http://www.youtube.com/user/Lowracerman#p/u/0/1d33uTjTXW8
5 lb thrust pulse jet engine that I built. http://www.youtube.com/user/Lowracerman#p/u/3/QkOR8IZPsFg
10 lb thrust pulse jet engine that I built. http://www.youtube.com/user/Lowracerman#p/u/4/jqxjgmelP-Q
Steam engine that I built. http://www.youtube.com/user/Lowracerman#p/u/1/5qVdQ-Ofv6c
Sterling engine that I built. http://www.youtube.com/user/Lowracerman#p/u/19/57GFrxz_mnw
Sterling fan that I built. http://www.youtube.com/user/Lowracerman#p/u/20/iSBXcn4u4es
Water fall. http://www.youtube.com/user/Lowracerman#p/u/11/JtAtikq4bgk
Water fall. http://www.youtube.com/user/Lowracerman#p/u/13/ch7jXxeml4k
Sterling fan that I built. http://www.youtube.com/user/Lowracerman#p/u/2/NBpRl5eF3fc
My Low Racer bike. http://i43.photobucket.com/albums/e358/gary350/low02.jpg
SR-71 Pulse jet engine. http://i43.photobucket.com/albums/e358/gary350/SR-71-02.jpg
Camping. http://i43.photobucket.com/albums/e358/gary350/FallCreekFalls023.jpg
Hiking. http://i43.photobucket.com/albums/e358/gary350/trail1.jpg
Hiking. http://i43.photobucket.com/albums/e358/gary350/HoneyCreek1.jpg
Bike. http://i43.photobucket.com/albums/e358/gary350/Bike02.jpg
This photo was taken with Kodak Wal Green put it on CD. http://i43.photobucket.com/albums/e358/gary350/tc3.jpg
This photo was taken with Kodak film Wal Green put it on CD. http://home.earthlink.net/~gary350/tc10-4.jpg
More Kodak film on CD. http://home.earthlink.net/~gary350/tesla2.jpg
More Kodak film on CD. http://home.earthlink.net/~gary350/sphere2.jpg
I don't have a video take type video camera that works anymore so I'm not sure if that will take a video of the TC sparks but it won't upload to You Tube. I want to upload to You Tube.
-----Original Message-----
>From: DC Cox <resonance@xxxxxxxxxxxx>
>Sent: Dec 25, 2009 5:45 PM
>To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
>Subject: Re: [TCML] Tesla Coil Video Problems
>
>Shoot with Kodak film (not Fuji), asa 400. Set camera timer to 4 sec (wide
>open lens time), and set F stop to F1.2. Most all of our shop photos are
>shot this method. We prefer older film type camera for best results.
>
>Also, some of the new color slide film works well if you can push the asa
>into the 400 to 800 range.
>
>Dr. Resonance
>
>
>
>
>On Fri, Dec 25, 2009 at 12:19 PM, Harvey Norris <harvich@xxxxxxxxx> wrote:
>
>>
>>
>>
>> --- 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
>> > _______________________________________________
>> > Tesla mailing list
>> > Tesla@xxxxxxxxxx
>> > http://www.pupman.com/mailman/listinfo/tesla
>> >
>>
>>
>>
>> _______________________________________________
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>> Tesla@xxxxxxxxxx
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>>
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