Myopia
New Member
How a 7510A works
How a 7510A works
The CRT is not a storage tube, like Tektronix monitors - it's an electrostatically deflected CRT with a very fast decay white phosphor. The CRT is driven at a fixed brightness that was optimized for best spot size (resolution), so the software draws each vector the number of times needed to expose the film for the correct time to get the brightness requested for that color in Red, Green, or Blue. As I recall, we just repeated each vector in stroke-generator memory the required number of times, and then the next vector, etc. When taking a picture, there's really just one line on the screen at any given time. In preview test mode, we would try to display as many vectors as we could, but without any color or brightness control.
To get sub-pixel positioning of endpoints (the actual D-to-A hardware had 2048 resolution) we dithered the endpoint coordinates, sharing the exposures between adjacent addressable points. This made the apparent endpoint position on the film image much better without fattening up the lines too much, leading marketing to claim 16K resolution, but the spot size was really closer to 2K.
How a 7510A works
The CRT is not a storage tube, like Tektronix monitors - it's an electrostatically deflected CRT with a very fast decay white phosphor. The CRT is driven at a fixed brightness that was optimized for best spot size (resolution), so the software draws each vector the number of times needed to expose the film for the correct time to get the brightness requested for that color in Red, Green, or Blue. As I recall, we just repeated each vector in stroke-generator memory the required number of times, and then the next vector, etc. When taking a picture, there's really just one line on the screen at any given time. In preview test mode, we would try to display as many vectors as we could, but without any color or brightness control.
To get sub-pixel positioning of endpoints (the actual D-to-A hardware had 2048 resolution) we dithered the endpoint coordinates, sharing the exposures between adjacent addressable points. This made the apparent endpoint position on the film image much better without fattening up the lines too much, leading marketing to claim 16K resolution, but the spot size was really closer to 2K.