Re: Video, frames and fields was Re: Hybrid-Maggy

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Robert Jones" <alwynj48-at-earthlink-dot-net> 

Oops got my frames and fields mixed up here is the correct version I hope

Bob
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Monday, January 12, 2004 10:44 AM
Subject: Video, frames and fields was Re: Hybrid-Maggy


 > Original poster: "Robert Jones" <alwynj48-at-earthlink-dot-net>
 >
 >
 >
 >  > Original poster: Harvey Norris <harvich-at-yahoo-dot-com>
 >  >
 >  >
 >  > --- Tesla list <tesla-at-pupman-dot-com> wrote:
 >  >  > Original poster: Bart Anderson
 >  >> primary and secondary arcing are separate in time)
 >  > Tapings of Mark Metlicas large coil showed that frame
 >  > per frame,many empty periods of non arcing exist,
 >  > which seem feasible for a very low natural res
 >  > frequency of long wire length. >
 >
 > This probably  has nothing to do with the frequency of the secondary if
 > that's what you mean.  It is usually caused by beating or aliasing of the
 > video frequency with the break rate of the coil. The video exposure time
can
 > be much smaller than a field period so if the break rate of the coil  is
 > close to the field rate or some integer of the rate and the only source of
 > light is the coil you can have an almost blank video except for the bleed
 > thru ( an effect caused the no zero sensativity out side the field
exposure
 > time. This is particularly noticeable on auto exposure and gain. The is
also
 > a bleed over effect to adjacent pixels particularly during saturation this
 > may account for fuzziness of some pics).  You can get a similar problem
with
 > digital still cameras.  When I first got blank pics from my still
dig-camera
 > I  assumed the RF field had disrupted its operation. The moral of that is
 > set the exposure time to at least one break period.
 >
 > I assume coil to video synchronization and the correct phasing via a
 > triggered gap would solve this problem. or a sufficiently high break rate
to
 > ensure one discharge per field exposure. Irritatingly as you suggest there
 > is also the interlace problem i.e. most video cameras build a frame from
two
 > fields so it not possible to get a full frame picture (high res) of  a
 > single discharge.
 >
 > I wonder how high resolution still dig-cameras create their frames in
video
 > mode i.e. from two consecutive exposures or from one?? This may be
 > irrelevant as the compression required to store a significant number of
 > frames in the storage media may produces poor quality images
 >
 > How did KVA get round the video problem or if they had the problem?
 > Synchronization, 240 break rate or just maximum exposure time?
 >
 > Has any one tried to observe streamer growth by examining a video field to
 > field?
 >
 > Bob
 >
 >