Originally Posted by Bjoern Roy
the quotes below are from a fellow HT freak, who contacted me about my setup. I will post the answer here for those who might be interested. There is also a more detailed explaination of my 'constant area projection' methodology. Have fun.
For 2.76 aspect ration films (Ben Hur?) is your screen width then about 117 inches?
Exactly! 117" width x 42" height for 2.76:1 content.
One other question: Is your screen (unmasked)in a 4:3 aspect ratio with a width determined by the widest aspect ratio film?
If you have a 4-way maskable screen it kinda doesn't matter how large the screen is behind the masks. The important thing you mention is that the screen has to have the width of the widest ratio film. For height, a 4:3 screen would be a lot too tall. Since the unused screenspace is masked anyway, it doesn't really matter, though.
Lets assume 2 practical scenarios here.1) Full blown Constant Area scenario (ultimate nerd alert)
You do care for 2.76:1 movies a lot and want to use the constant area scenario for ALL formats, including 2.76:1. Then the minimum screen ratio surrounding all formats is 1.92:1. For example in my case: screen width is determined through the widest ratio 2.76:1, thus 117 inches. Screen height is determined through the tallest ratio 1.33:1, thus 61 inches. 117" / 61" = ~ 1.92:1. It would not make much sense to actually buy a screen in a 1.92:1 ratio, though. You would simply buy a 117' wide 1.77:1 or 1.85:1 screen and have an inch or two unused above and below.
I would suggest to implement these ratios in this full blown configuration: 1.33:1, 1.66:1, 1.78:1 (or 1.85:1), 2.35:1 and 2.76:1. All of these modes would use the same area on screen.
You could also implement 1.37:1, but thats too close to 1.33:1 to be worth the effort. Simply use the 1.33:1 mode and narrow the vertical masks slightly if a transfer is actually properly framed to 1.37:1.
Same with 1.78:1 which isn't even a real format. Having a mode for 1.78:1 AND 1.85:1 is also not really worth the effort. The two are VERY close, so just choose either one. I would suggest 1.78:1. Most 1.85:1 transfers are actually framed at 1.78:1 anyway. Simply use the 1.78:1 mode and narrow the vertical masks slightly if a transfer is actually properly framed to 1.85:1 like Starship Troopers.2) CA 'light'
Its kinda silly to take 2.76:1 movies into account if you don't have many, if any at all. So you could simply use the modes listed in 1) but without an actual 2.76:1 mode. Then you would watch a rare 2.76:1 presentation in you 2.35:1 mode, and again, narrow the vertical masks slightly to mask the letterboxing.
In this scenario, the minimum screen ratio surrounding all formats is exactly 1.78:1, what a nice coincidence! Or maybe this is why they came up with 1.78:1 in the first place?
To clarify: The screen width needed here is determined through the widest ratio 2.35:1, in my case 108 inches. Screen height is determined through the tallest ratio 1.33:1, thus 61 inches. 108' / 61' = ~ 1.78:1. So you could simply buy a 1.78:1 screen. Good for resale value, too.
I prepared another figure to show again how the different scenarios actually look like:
My preference is from left to right.
I already posted a comparisson in a post above with pics comparing TS2 and Twine, so these comments here are just to further clarify these comments and bring the other formats into the discussion. I will include the pics again for convenience:1) Constant Area
Pros: all ratios seem to have the same "size". None of them are too small or too big. You simply adjust your seating distance to you liking for, lets say, 2.35:1 movies and the others all look perfect too.
Cons: variable 4-way masking needed2) Maximum Size within 2.35:1 screen
Pros: easier to implement than 1). Except for 2.76:1 material,only horizontal masking needed (curtains). 2.76:1 material would be slightly letterboxed and if no vertical masking is available, wouldn't have the full impact of a properly masked presentation. The need for 100% masking can't be stressed enough, really!
Cons: All formats smaller than 2.35:1 are too small for my liking, but as i already said, i still prefer this over the 16:9 solution. To make a 2.35:1 screen work, you adjust your seating distance so, that you sit a tad too close for 2.35:1 movies (lets say 1.3-1.4 times screen width, instead of my 1.5 times recommendation). Then 2.35:1 is slightly too big and 1.85:1 is slightly too small, but all in all, both look great. 1.33:1 is outright puny! But you could argue 'who cares'? 1.33:1 is not meant to be epic anyway. If you watch a lot of 1.33:1 television stuff, this might be a problem for you. But i would argue that most 4:3 material (e.g. NTSC broadcast) is terrible in quality anyway and not worth getting projected too big.3) Maximum Size within 1.78:1 screen
Pros:Very common, pretty much straight forward.
Cons:You still need 4-way masking! So you could go the extra mile for 1) if at all possible (projector memories etc...) In scenario too, you could adjust your seating so that its a compromise between 2.35:1 and 1.85:1, just like in 2). Only that now 2.35:1 look somewhat small and 1.85:1 somewhat big, which i simply don't like. So the only other option would be to adjust seating so that 2.35:1 looks perfect, but then 1.85:1 movies look enormous.4) Constant width in 4:3 screen
Pros: If you don't watch movies, this is great
Cons: Well, better don't get me started.
I really tried to keep it short. REALLY!