EEV Image Isocon type P850 size comparison
This tube is possibly the largest and most complex camera tube ever made, dwarfing even the 4.5 inch Image orthicon tube.
The 18mm. Plumbicon is included to give an idea of the size of the image Isocon tube. EEV made at least 2 other smaller tube sizes, one being the 3 inch type P880 version that could be used, with some modifications to the camera, in a standard 3 inch I.O. camera.
This tube was used in the Marconi Instruments OA1706 Image Isocon Television Camera.
The undated tube's box for the P850X tube is labeled University of Southampton Space Physics.