The RCA TK-40 is considered to be the first practical color television camera, initially used for special broadcasts in late 1953, and with the follow-on TK-40A actually becoming the first to be produced in quantity in March 1954. The TK-40 was produced by RCA Broadcast to showcase the new compatible color system for NTSC—eventually named NTSC-M or simply M—which the company is credited with inventing (though several other companies including Philco were involved in development). Color had been attempted many times before, often in a semi-mechanical fashion, but this was the first series of practical, fully electronic cameras to go into widespread production. The camera was quickly followed with the TK-41, a line that shared a very similar shape, but featured streamlined and enhanced electronic subsystems. Earlier TK-40s are distinguished by the lack of venting slots on the sides (the cameras were prone to overheating, necessitating the addition of these openings). The last variation of the TK-41 was the TK-41C, released circa 1960. The cameras are considered to have been of very good quality, better than the very different TK-42 which succeeded the TK-40/41, and probably better than anything produced by RCA for several years after the production line shut down (NBC didn't fully replace their TK-41s in Rockefeller Center or their Burbank, California broadcast facility until the release of the TK-44A around 1968). Prior development in the late 1940s and early 1950s had included the TK-X (for "experimental"). An image (beam) splitter was used in the TK-40/41 to direct the incoming light into three image orthicon tubes for recording moving pictures in the red, green, and blue component colors. The early cameras required a very large amount of lighting, which caused television studios to become very warm due to the use of multi-kilowatt lamps (a problem that still exists somewhat today, but is less pronounced). The RCA TK-40 and TK-41 color cameras required more than an hour to set up and were comparatively unstable, making frequent adjustment necessary to maintain correct color balance between the red, green, and blue primary colors. These cameras also required complicated control consoles and rack-mounted power supplies for the camera's many vacuum tubes and ventilator fans cooling their large image orthicon tubes. The cameras, which weighed hundreds of pounds on their own, were only one component of the TK-40/41 system. There were also backend devices placed in the control rooms (camera control units and