View Full Version : Image Dissector Question


Rinehart
07-22-2012, 01:07 AM
Can anyone tell me if it is possible to use a non-storage pickup tube like an Image Dissector in a Telecine? If so, are there particular problems that you have to get around?

old_tv_nut
07-22-2012, 09:06 PM
Can anyone tell me if it is possible to use a non-storage pickup tube like an Image Dissector in a Telecine? If so, are there particular problems that you have to get around?

Rinehart,

It's *possible*. Getting enough light is not a problem, of course.

A dissector has the same problem as a flying spot telecine in that the film must stand still for the full scan time, and then be pulled down to the next frame very rapidly during vertical retrace time.

Fink (1952) states that this did not find any extensive use in 60 Hz scanning because of the stress on the film. In 50 Hz countries, flying spot telecines were built with the film running continuously (not pulled down intermittently),4% fast (25 fps), and optical stabilization of the motion was used. 60Hz countries used iconoscopes instead, with a pull down speeded up by about 1/3 compared to usual theater practice. In using the iconoscope, the projector shutter is open only during the vertical blanking, and then the iconoscope scans the stored image.

I note there are inexpensive copies of Television Engineering (Fink, 1952) available at abebooks.com:
http://www.abebooks.com/servlet/SearchResults?an=fink&sts=t&tn=television+engineering

I recommend you get a copy, since it seems to answer many of the questions you have posted here.