Videokarma.org

Go Back   Videokarma.org TV - Video - Vintage Television & Radio Forums > Television Broadcast Gear

We appreciate your help

in keeping this site going.
Reply
 
Thread Tools Display Modes
  #16  
Old 03-13-2012, 12:01 AM
Rinehart Rinehart is offline
VideoKarma Member
 
Join Date: Nov 2011
Posts: 129
Wow. Why did it need such intense lighting? From what I've gathered, early Iconoscopes needed something like 1,000 ft-candles, and that was an insufferable amount. What 2,500 ft-candles was like I can only wonder about.
__________________
One Ruthie At A Time
Reply With Quote
  #17  
Old 03-13-2012, 10:17 PM
old_tv_nut's Avatar
old_tv_nut old_tv_nut is offline
See yourself on Color TV!
 
Join Date: Jul 2004
Location: Rancho Sahuarita
Posts: 7,184
For one thing, the vidicon target voltage (and therefore sensitivity) had to be kept low to minimize dark current variations (shading). Plus, the lag was much worse with a high target voltage. Also, the relay optics were not very efficient, plus absorptive trimming filters were needed to get the color response right.

All the illustrations of usage I have seen are for surgery, microscope slides, or graphic charts, except for the "see yourself on color TV" exhibit at the Museum of Science and Industry in Chicago. The lighting for that consisted of a row of PAR bulbs that cast dark shadows in the subjects eye sockets and still were almost blinding. Even so, the lag was pretty awful. When someone stepped in front of the background mural, you could see the palm frond "through" them for several seconds. I don't think anyone used this camera for live studio work.
Reply With Quote
  #18  
Old 03-13-2012, 10:56 PM
Rinehart Rinehart is offline
VideoKarma Member
 
Join Date: Nov 2011
Posts: 129
Sorry, what are PAR bulbs?
Also, to ask a couple more questions, some of the television primers mentioned that WRGB, amongst others, experimented with mercury vapour lamps like the ones in the two pictures I've attached. The large housing is for a water-cooled jacket, and the principal drawbacks were the expense, the weight of the lamp, and that the jacket sometimes leaked. I think there were some issues, too, with the emission spectrum, which caused colours to be rendered into gray scale in unusual ways. Does anyone know how widely this kind of floodlighting was used?
Attached Images
File Type: jpg circus_program_wrgb_1940s_sjpg23000.jpg (73.3 KB, 10 views)
File Type: jpg an_evening_at_william_s_grill_1944_sjpg24300.jpg (74.4 KB, 11 views)
__________________
One Ruthie At A Time
Reply With Quote
  #19  
Old 03-14-2012, 06:37 AM
old_tv_nut's Avatar
old_tv_nut old_tv_nut is offline
See yourself on Color TV!
 
Join Date: Jul 2004
Location: Rancho Sahuarita
Posts: 7,184
Parabolic Aluminized Reflector - like the floodlights used for many decades in outdoor security lamp fixtures
http://www.diynot.com/forums/viewtopic.php?t=139441

Edit - by the way, I do not know how widely mercury lamps were used in TV.
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 07:17 PM.



Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
©Copyright 2012 VideoKarma.org, All rights reserved.