Why did the color roundies have the mask?
 

That made the top and bottom flat unlike the portholes? If you took off the mask and adjusted the picture would it show up on the whole screen like the old b&w portholes? I really like that look.

Round might look interesting to us collectors, however back in the day it was probably an irritation to anyone that wanted their modern TV to look like the big screen at the movie theater. I would think the porthole novelty wore off pretty quickly. But sure, you could modify your color roundy if you enjoy the look.

For the rectangular look.
On some of those old sets it was hard enough to get enough vertical deflection, let alone enough to give it a porthole look. Remember, sets had to be affordable to operate and repair.
Help me out on this one, guys.
I know many FBPs had lettering and/or numbering on the bottom portion of the screen, covered by the mask, that would have shown in a porthole. I can't remember if the bonded ones had lettering/numbering or not.
Masking the sides of roundies would have further reduced the viewable area. But...you didn't have to worry about those pesky corners when replacing a roundie. :banana:
Phil

Yes, there's markings on the bonded types. The FB/FJP's share the same envelope. Sometimes you may even see a glass imperfection in those areas too.

Round "porthole" TVs look cooler when they're turned off than when they're actually playing. I think the porthole design was an impractical gimmick (or perhaps simply naïve design), and that's why the vast majority of B/W sets with round tubes used rectangular masks.

A TV image is by definition rectangular. If you expand it to fill a round screen vertically, then you lose a bunch of the picture in the corners. If you shrink it to fit the entire image on the screen, then the round tube looks dumb, with big blank areas for no apparent reason. Some B/W porthole sets even had a switch allowing you to flip from one screen mode to the other, suggesting that the manufacturer knew that neither of those compromises would satisfy everyone.

Anyhow, there's nothing to prevent you from making a porthole color roundie, if you want to throw away your mask and you can get enough vertical deflection from your set.

Phil Nelson

Besides the fact that all round color tubes I've ever seen didn't have a full silk screening of color dots at the very top and bottom of the tube, I think it would look terrible. They have what looks like registration marks top and bottom.

And of course, everything would look tall and thin, because you wouldn't have the corresponding horizontal expansion.

Yes, if you expand only the height, then the aspect ratio will be off. I believe that one of the switchable B/W porthole sets (perhaps the Stromberg-Carlson with the "opera glass" switch) expanded both width and height, to preserve the correct geometry in the portion of the image seen in the round tube. Of course, then you lose more of the rectangular image, but that's life with a porthole!

Phil Nelson

I think the real answer to the question is, the transmitted image was designed to be in 4 by 3 format. IF you take a test card and display it with the center circle on a set that is perfectly adjusted so that the circle is perfectly round, you will see that you will be missing the corners of the image on a round tube set. If you shrink the image proportionally to see the missing corner images, you will have large blank areas on the sides and top and bottom.

The truncated top and bottom of the round crt is so as to be able to achieve the correct left to right width, and a correct top to bottom height without distortion of the picture and without a blank space above and below the image on the screen. But you will still have missing image in the 4 corners because the tube is round and not rectangular.

Round color porthole?
 

Boy, Kevin you are sooo right!! I recall my father saying "Damned ol' round screen!!" more than once when our 1965 Zenith color roundie cut off words - or ball scores, at the bottom of the screen.

Didn't bother me as a kid, except for the fact that our set looked less modern, and therefore less correct, when I compared it to friends' color sets, especially when we were still using it in the early '70's.

Now I'm just hoping for a chance to restore that Zenith some day.

I am 66 years old. I remember the round screen color sets when I was a teenager. When the CTC-28 came out, dad bought one and it was our first color set. I loved it and hated the look of those old round sets.

Fast forward. I still have the CTC-28 (and a new CRT for it) and I have a CTC-9 that works but is not restored yet. So, I guess I am guilty of the same. Funny how age makes you appreciate more in life.

Because they couldn't very well go out in public the way they were.