August 19, 2010

Wide or Even Wider?

I am in the midst of deciding on the home theatre for my new room -see my post from yesterday “Peanut Butter and Jelly or Oil and Water”.

The first thing that needs deciding is the projector screen’s aspect ratio and size. There are 2 aspect-ratio choices nowadays – widescreen 16:9 (or 1.78:1) or the even wider 2.35:1 format. The old 4:3 format, which is used in our ASTRO feed, our free tv broadcast, and the CRT TVs in our homes, is really not in contention anymore.

16:9 aspect ratio projection screen
(photo taken in AV Designs)

The 16:9 format does not require much explanation, we are used to seeing it by now. Plasma & LCD TVs are all in this aspect ratio (though I have seen Philips coming out with a 2.35:1 TV once), almost all projection screens that we encounter are in this aspect ratio too.

Many major motion pictures nowadays are shot in the 2:35:1 aspect ratio though, you see them in cinemas. If this type of movie is projected onto a 16:9 screen, there will be horizontal black bars on the top and bottom of the screen. The black bars are wasted resolution from the projector (pixels that are not used for the image). A full HD projector has 1080 rows of vertical resolution. If a 2.35:1 aspect ratio movie is played, then only 810 rows will be used for the picture part in order to preserve the aspect ratio, the rest is wasted on the black bars – you see the huge drop? You lose as much as 25% of the resolution.

There is a way though to utilize all the pixels in the HD projector while at the same time viewing the movie in all its 2.35:1 glory. This requires extra investment (there is no free lunch!). There are 2 items to invest in.

One is the screen - you’ll have to ditch the 16:9 screen and opt for a 2.35:1 one.

A 2.35:1 aspect ratio screen, note the additional width
(photo taken in AV Designs)

The other is the addition of an anamorphic lens. You see, to ensure that the entire resolution of the projector is used, the trick is to electronically stretch the 2.35:1 movie vertically into 16:9 aspect ratio to occupy all the available pixels. Many projectors and DVD/Blu-ray players can do this. However, when this stretched picture comes out on the screen, it will appear squeezed, everything will look slimmer and taller. In order to restore the correct aspect ratio, the anamorphic lens is placed in front of the projector, its job is to stretch the 16:9 image horizontally into 2.35:1 to fill the entire screen. Interesting, I learned something new.

Anamorphic lens from Panamorph installed in front of a projector
(photo taken in AV Designs)

What if now you want to watch something shot in 16:9? You can move the lens away, the image will then be projected fully on screen but with the left and right sides of the screen not used. Or if you are lazy, you can playback the 16:9 movie in 4:3 format in the player, the anamorphic lens will stretch it to 16:9 (you’ll lose horizontal resolution in the projector this way). Or you can just let the lens stretch the 16:9 image into 2.35:1 anyway, with the consequence of cropping a bit of the top and bottom part of the image off.

Have you shut down already due to these convoluted descriptions from me?

Anyway, if you interested to explore the 2.35:1 screen format, you can contact James Tan of AV Designs, he can demo it to you in his showroom. AV Designs carries the Panamorph Model A480 Professional Grade Anamorphic Lens System for this purpose. It also has a nice room set up for viewing in 2.35:1 aspect ratio.

Close-up of the Panamorph lens
(photo taken in AV Designs)

Now, reality - my budget definitely can’t touch the 2.35:1 system, so I’ll settle on 16:9. What screen size? James’ advice is to get one as wide as the room and viewing distance can take. I’ll go for minimum 100” diagonal. Size does matter in home theatre, I believe. Have you seen demos where the sound was really grand but the screen was disproportionately small? The sound does not seem to come from the screen at all, they are disjointed and the experience is totally diminished.

If you are interested, I came across this Home theatre Calculator spreadsheet, you can use this to calculate screen size and viewing distance and see whether the combination meets recommended standards ->

That’s it for now, more to come later…

Panamorph is available from AV Designs, contact James Tan 016-3280237


junchoon2989 said...

with these Epson projectors, i think u can skip the anamorphic lens


OdioSleuth said...

Interesting information.
Thank you.