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We had a Mitsubishi first generation HD (tube rear projection) for years and had to deal with the above adjustments for some time. As HD camera usage became the norm, we needed less adjustments.
It depends on what you are trying to do. I also had a Mitsubishi DLP TV. I have never needed to use the "stretch" or "zoom" controls except in rare instances. If a movie is shot in 4:3 (Casablanca, Gone With the wind, et al) I watch the film in that ratio and have black bars on the sides. Same holds true for older TV shows. If I am watching a film with a wider aspect ration than 16:9 (e.g. Ben-Hur, Lawrence of Arabia), I will have black bars at the top and bottom of the screen. The only time I use the zoom function is if I am watching an old non-anamorphic widescreen movie like a laserdisc or an old DVD. The picture will have to be zoomed to fill up the normal widescreen area and will probably look distorted.
Yes. Those movies were the early days of Cinemascope that were shot in mostly 2.35:1 ratio and will still have black bars. Any other shot in 4:3 will still be shown in that ratio on new displays, unless re-mixed to fit 16:9 which will cut off a lot of the image. However, my 4k LG OLED up-scales the resolution and colors to an amazing picture. I watched the original True Grit in 4:3 and it looked like a new movie other than the bars.
Interestingly, when HD first came out, directors started shooting in the same 16:1 ratio. Other than small movies like RomComs, the big action movies are now shot in the Panavision (Scope) 2.35:1 of those days or some varying degree of that aspect ratio. Then you get the bars again since they are shot for a wider theatrical screen than all HD tv's with 16:9.
Since we never go to theaters anymore, are the non-reflective curtains still in front of the screen so the projectionist can adjust for aspect ratio?
Also, I have a 3 yr. 16:9 projector and 16:9 110" screen. I know you can buy a movable lense for the projector for 2.35:1 viewing, but would have to replace the screen to fill that ratio which are available. Haven't kept up, are there fair priced 4k 2,35:1 projectors on the market? We stopped using the Theater because I got tired of the grayish bars and the poor contrast in night skies and shadows. It wasn't close to contrast of the our new 4k OLED nor our old HD rear-projection.