BBC Aspect Ratio Change 1950

[stevehertz]

Originally Posted by peter_scott

I must say I don't like the American approach to round CRTs of vignetting the corners.

Peter

That's not really vignetting, and it's certainly not just applied to the corners (all masks are 'rounded' in the corners) it's the sides of the mask that are curved as opposed to straight. And it wasn't just America, the UK's Bush TV12 was the same, and differentiates it at a glance from the later TV22 that had a straight sided mask.

[Graham G3ZVT]

Originally Posted by peter_scott

I must say I don't like the American approach to round CRTs of vignetting the corners.

Peter

My Cossor 916 has precisely the same "Double D" profile.

What I find a bit strange are those totally unmasked American "port-hole" sets that don't seem to have a British equivalent, except for home-built ones.

(Crossed with stevehertz)

[stevehertz]

Originally Posted by rambo1152

My Cossor 916 has precisely the same "Double D" profile.

What I find a bit strange are those totally unmasked American "port-hole" sets that don't seem to have a British equivalent, except for home-built ones.

(Crossed with stevehertz)

Well, given that the CRT's image was rectangular, I think it just shows that British designers had a tad more sense and 'design finesse' to at least attempt to match the mask to that rectangular image as best as they could. A crystal ball it is not.

[Nuvistor]

UK sets were sold with the CRT size whereas the USA sets seem to have had the picture area in sq inches. So is it possible the double D and round screens would have a larger area of picture and a bigger selling point?

[mark pirate]

What I find a bit strange are those totally unmasked American "port-hole" sets that don't seem to have a British equivalent, except for home-built ones.

There was at least one British "Porthole" set made by Regentone.
Does anyone know of another?


Mark

[Heatercathodeshort]

I have only seen a picture of one of those. I think the model number is TR20L with mains derived EHT. To be honest it looked exclusive and expensive! J.

[mark pirate]

I believe it was the first set produced by Regentone, I Recall a forum member has one.
There is shown on Jon's wesite; http://www.thevalvepage.com/tvmanu/regentone/regentone.htm



Mark

[stevehertz]

With a porthole screen you have the ability or 'option' to expand the image to fill the screen albeit with the corner and some side information missing. On reflection probably not a high price to pay for a seemingly larger image.

[Dave Moll]

Originally Posted by mark pirate

I believe it was the first set produced by Regentone, I Recall a forum member has one.
There is shown on Jon's wesite; http://www.thevalvepage.com/tvmanu/regentone/regentone.htm



Mark

Thanks for clarifying what was meant by "porthole" - I hadn't recognised the description. Indeed there is a member who has one...

I had a cheapo, found at the side of the road, 14" colour TV in my workshop 20 odd years ago, the line width wouldn't go to the edges and I couldn't bother fixing it so I set the height to give the correct 4:3 ratio. This showed H sync, VITs and CEEFAX, I called it my techy telly. At least I saw the whole picture.

[Graham G3ZVT]

Originally Posted by merlinmaxwell

I had a cheapo, found at the side of the road, 14" colour TV in my workshop 20 odd years ago, the line width wouldn't go to the edges and I couldn't bother fixing it so I set the height to give the correct 4:3 ratio. This showed H sync, VITs and CEEFAX, I called it my techy telly. At least I saw the whole picture.

That's precisely how some studio monitors were (are?) set up in the more discerning departments, where the engineers literally needed to see the "whole picture".

I was occasionally asked set up domestic TVs with under-scanning for Granada Studios.

[McMurdo]

I'm sure the late chipp1968 had a porthole regentone.

My Baird 'coronation fifteen' boasts a 'double-D scan giving maximum picture area'. (15in round crt). I think it looks vaguely american.

[FERNSEH]

Back in the mid-sixties it was observed that the picture width had decreased slightly, this was more noticeable on the newer 19" and 23" "square screen" displays which have 4 :3 screens.
At the time I had no idea what had caused the effect, simply readjusted the width control to bring the picture to the edges of the screen again.
Later on I learnt the effect was caused by the origination of the 405 line signals. After conversion from 625 the active video part of a 405 line period became 80microseconds.
The original 405 active video part occupied 83microseconds of the 98.8microseconds of a picture line.

DFWB.

[red16v]

Originally Posted by rambo1152

That's precisely how some studio monitors were (are?) set up in the more discerning departments, where the engineers literally needed to see the "whole picture".

I was occasionally asked set up domestic TVs with under-scanning for Granada Studios.

That was certainly the case in the analogue era. Also, in some VTR departments, it was often the case that the monitors needed to present a picture with delayed horizontal and vertical syncs so that the equalising pulses could be observed (We needed to see them for editing purposes). This ‘mode’ was called pulse cross.

[Heatercathodeshort]

The majority of the receivers fitted with the Mullard or English Electric 16" metal cone circular tube were fitted with 'Double D' masks to give the maximum picture area of the screen possible.
A large number of makers produced just one example employing the MW41-1/English Electric T901 16" MC tube. Just one year later the rectangular 17" all glass tube was available quickly replacing the unpopular 16" MC.
The attached picture shows the 1951 Ferguson 989T with MW41-1 tube, one of the rare ones to employ a conventional mask. John.

[Graham G3ZVT]

Originally Posted by FERNSEH

Back in the mid-sixties it was observed that the picture width had decreased slightly, this was more noticeable on the newer 19" and 23" "square screen" displays which have 4 :3 screens.
At the time I had no idea what had caused the effect, simply readjusted the width control to bring the picture to the edges of the screen again.
Later on I learnt the effect was caused by the origination of the 405 line signals. After conversion from 625 the active video part of a 405 line period became 80microseconds.
The original 405 active video part occupied 83microseconds of the 98.8microseconds of a picture line.

DFWB.

Some NTSC conversions seemed to have a black margin on the RHS.

The daily Sesame Street episode, either by design or accident, filled the gap by repeating the last few microseconds of the active line a few times as a filler. This would be about 1971/72

[Maarten]

Originally Posted by Dave Moll

I can't say that I've ever seen TV aspect ratios quoted as height:width, i.e. 3:4 or 4:5 (and certainly not 9:16).

I think it might indeed be the other way around. The TV ratio 4:3 would correspond with the cinema ratio 1:1.33

[rford]

Perception of AR across the board in my experience has been very varied.
And let's face it, back in the 80s when I was traipsing around many domestic customers were so unfazed by poor CRT emission ("it's fine if you wait 20 minutes and close all the curtains, dear") and rubbish vertical linearity, that it didn't seem to matter too much about Aspect ratio.
I was in broadcast and film by the time 16:9, 14:9 and all those other wonderful things became a thing - I always remember an aunt asking me why there were big black bits top and bottom when a film was being shown (that wasn't pan and scanned) and around the same time realising that the Americans mostly hated pictures that didn't go right up to the edges.
My own personal hate these days is the opposite: where some old 4:3 footage has been dropped into a modern program but they cut the top and bottom off rather than use pillarbox (which would be my preference).
But that's just my own subjective opinion, and many others will disagree... or perhaps more likely ... not even notice!!

[peter_scott]

Originally Posted by rford

My own personal hate these days is the opposite: where some old 4:3 footage has been dropped into a modern program but they cut the top and bottom off rather than use pillarbox (which would be my preference).
But that's just my own subjective opinion, and many others will disagree... or perhaps more likely ... not even notice!!

I tend to agree. I dislike the loss of active frame area but my dislike of wrongly proportioned images is even stronger. That said, when displaying current broadcast 16:9 I am happier to crop the left and right sides for display on old television sets than I am to display as letterbox.

Peter

[TIMTAPE]

I agree but its more than just personal preference. 35mm and larger feature films had far better picture detail than the old TV systems. Zooming in on a wide-screen film image traded off left and right detail for retaining more of the 35mm detail. But with today's HD TV systems, even with the black bars on left and right, a 4:3 image from a videotape of an old TV show presents all the original picture detail. Zooming in is not necessary as it was before HD TV. No need for the previous trade off. Presenting movies for SD TV often involved presenting wide-screen title shots in letterbox or squeezed anamorphic, and then cutting to zoomed in, or pan and scan for the rest. A lot of work for the studio then which should be unnecessary these days... I hear Peter Jackson's recent Beatles re edit of the original 16mm 1.33 footage is presented in something like 1.66, which allowed him to do - for better or worse - not a pan and scan but a tilt and scan.