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Videoscoping vs Digiscoping
Created on 16 May 2001. Copyright Dr Chan Kai Soon.
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This section tabulate my understanding of the practical differences between digiscoping and videoscoping. The differences are due mainly to different specifications between camcorders and digicams in terms of the number of pixels per CCD and the lens system or optical zoom. Camcorders typically have less pixels for the CCDs, longer zoom lens and are mostly larger/heavier than digital cameras. Presumably, less pixels for a given CCD size means that these pixels are larger (read more sensitive because they can gather more light) and have a larger angle of view (read a lower resolution and longer optical zoom limits). Most of what I tabulate below are based on the above assumptions. 

Digiscoping : Taking still pictures with digital camera coupled to a spotting scope. 
Videoscoping : Taking videos with digital camcorders coupled to a spotting scope.
 
Videoscoping Digiscoping
Sensor design Camcorders come in one or three CCD models All digicams are single CCD
Sensor pixels The highest CCD use so far is less than 2K pixels. However, only about 380K pixels are actually required by the video. Digicam CCDs are getting better and better. Most digicams have more than 3 mega pixels.
Sensor scan method Interlaced i.e. 'half' resolution. Few camcorders (e.g. TRV900) have progressive scans as an option but at the expense of a slower frame rate. 'Progressive' 
Recorded Resolution The video frame in the MiniDV format is 720x480 (NTSC) or 720x576 (PAL). When saved in the interlaced mode, the vertical resolution of each field is only half of the above. As of May 2003, high definition camcorders that save at 1280x720/30fps (progressive) are beginning to appear on the market. Depends on CCD but typically they have much higher resolution. Pictures taken with the Nikon Coolpix series had been known to print satisfactorily at A4 size.
Dimension and weight Camcorders with some exceptions are larger, heavier and have a different form factor. Balancing the setup is a bigger problem. Smaller and lighter. Hence, easier to carry the setup and balance it on the tripod head.
Camcorder optical zoom Most camcorders have a maximum zoom of about 10-12X. Using less than this zoom often produces vignetting which is the main obstacle to successful videoscoping. Digicam zooms are mostly 3X but some models with up to 10X zooms are also available.
Effective optical zoom Generally higher than digiscoping. Problems associated with higher zooms include difficulty in spotting the bird, more obvious vibration and difficulty in composing the shot. Chromatic aberration also tend to be worse. Using 20-60x eyepiece 
3x20-60=60-180X 
Note: With a 3 megapixel 3x zoom digicam, the maximum resolution would be attained at about 30x eyepiece power. Use of eyepiece power beyond this would be of no benefit.
Use of scope for birding Scopes with 10x eyepiece zoom will not be suitable for general birdwatching purposes Scopes with 20-60X zoom are normally used for birding. Adaptors such as the Cheang and the Scandinavian designs allow use of scope for normal birdwatching and rapid mounting of the digicam for digiscoping when the need arises.
Low light situations Camcorders requires much less light for satisfactory video. Digicams requires much more light unless a higher ISO setting is used. May be feasible with slow shutter but requires high degree of skill.
Depth of view Very shallow due to generally higher zoom. Shallow
Vignetting Usually marked and difficult to avoid. Less of a problem with some digicams such as the Nikon Coolpix series.
Focussing modes. Usually manual focussing using the scope. True spot focus usually not available. Many focussing modes available including spot focus.
Exposure modes. Exposure modes limited. Aperture priority mode not availabe in most SONY models. Manual exposure usually available and is useful in extreme contrast situations. The default chrominance in video is usually darker than that for digicams. Exposure modes usually includes aperture or shutter priority. Manual exposure usually not available. Exposure shift may not be adequate for compensation in extreme circumstances although post processing may be able to help.
LCD LCD are generally larger and easier to view under sunlight. Important for full manual focussing. LCD generally smaller.
Birds in flight Can be recorded with some practice More difficult.
Bird calls and behaviour Recorded/illustrated well. Not recorded. Video mode resolution up to 320x240 and 15 fps in most models.
Post-processing Some degree of twinkling of the sharpness, chrominance and color saturation etc could be done on computers with appropriate configurations. Sharp learning curve for NLE (non-linear editing) with computer system. Problems like vignetting, vibrations and chromatic aberration could not be corrected. Post-processing can do a lot to improve the still picture quality. Vignetting can be cropped off or reduced by digital darkroom techniques. Color balance or chromatic aberration can be corrected or compensated too
Cost of saving recordings DV tapes are much more expensive. Require another camcorder, computer or DV deck with firewire links to do digital editing. Much cheaper to archive pictures on CD
 
Links and references: 
  1. Digiscoping parameter spreadsheet by George Raiche - Calculate what is the resolution limits for your setup. 
  2. Resolution limits. Read Jay's post about resolution limits archived at Birdingonthe.net. He recommends about 10X (scope magnification) for every inch of scope aperture for digiscoping purposes. So far, I have not found any recommended limits for videoscoping.
  3. Video Fields - interlaced video explained at GreatDV.
  4. The miniDV format technical specifications - From Adamwilt.com
  5. The world's first High Definition prosumer camcorder - The JVC GR-HD10U
  6. Videomaker Test Bench: JVC GR-HD1MiniDV and HD camcorder. 
  7. Major Breakthrough in High Definition Camcorders. The four largest camcorder manufacturers (Sharp, Sony, Canon and JVC Victor) have joined together to develop and agree on a standard format for recording video in consumer high definition television (HDTV) camcorders. The standard will provide for recording video in 720 line progressive scan resolution or 1080 lines interlaced resolution.
  8. The Scandinavian digiscoping adaptor 
 
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