Quote:
Originally Posted by ceebee23
BUT one thing that has always slightly puzzled me looking at the roundies is just what size rectangular screen do they approximate.
They seem to look quite large? 25"?
Pardon my iggoranz but on this side of the world we never actually see such rare beasties in the wild.
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You are very close!
Remember in the mid 1950's, they still measured the glass (or metal) envelope and not the viewable screen itself until the US government required that the measurement to be the viewable portion.
For instance, per RCA's 1957 spec sheet, on the original 21CYP22 that the Ampico-Kid mentioned on his 1959 Caufield, the outside envelope measures 20 and 13/16ths inch with a tolerance of + or - 1/8th inch. (The outside glass had to be over 20.5 to be counted as a 21 inch.)
The usable image area is 15 and 1/2 inch high and 19 and 1/4 inch wide, and since it is round, the actual diagonal is also 19 and 1/4 inch.
If this were compared in size to a rectangular image in modern diagonal width measurement this equals:
(15.5 squared) plus (19.25 squared) = square root of total
or just a smidgen over 24 and 1/2 inches diagonal, if it were a rectangle.
Hope this simplifies things.