Hi,
 
for a digital video camera, is the film back width the CCD dimensions?
 
the specs in the manual for my digital vid camera say the CCD is "4.5mm (1/4 type)". is the 4.5mm the diagonal legth across the CCD, and what does "1/4 type"  mean.
 
the camera lens has a focal length of 4.2-42mm which the manual says is equivalent to 48-480mm for a 35mm camera.
 
i shot my footage using the widest angle so it was with a focal length of 4.2mm.  should i be setting my focal length to 4.2 and entering in the film back width for the CCD, or should i be setting the film back width to that of a 35mm camera and putting the focal length at 48mm?
 
i've searched quite a lot on the internet before posting here.  searching for "film back width" on google returns a depressingly small number of results, and also no camrea manufacturer states what theirs is in the specs for the camera.  ...well at least not in the format that matchmover needs.  i have read quite a lot on photography and lenses, and have found it fairly complicated.

Hello,
 
What is important, more that the size of the filmback, it's the ratio (between width and height).  
 
The final pixel aspect ratio will be the film back ratio divided by the image ratio. If your image is 720 x 576, your image ratio is 720/576 = 1.25.
 
This resolution is likely to be PAL. If you select standard PAL film back ( 20.12mm x 15.09mm, ratio 1.333), it gives you a pixel ratio of 1.333/1.25 = 1.0667.
If you want squared pixels (that means a pixel ratio of 1.0), you should have a film back ratio that is the same as your image ratio.  
For example, a filmback of 20.12mm x 16.096mm (ratio 1.25) will leads to a pixel ratio of 1.0
 
Then, for the focal length, you should use the 35mm equivalent (48mm in your case).
 
Hope this helps.

yes, thanks.