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David T. Nethery

1.85:1 aspect ratio : 2048 x 1107 or 2048 x 1080 ?

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Posted (edited)

I hope some knowledgeable person here can help me settle something.   I'm assisting a friend with setting up his animation project , which at first was going to be done at 16:9 HDTV aspect ratio
at 1920 x 1080 , but he is now considering whether to work at 1.85:1 theatrical aspect ratio.  I thought that 1.85:1 was 2048 x 1107  and that 16:9 was 2048 x 1152 because on several different websites I've found handy 'Aspect Ratio cheat sheets'  posted which give those numbers,  for example here :

https://dannybribiesca.com/aspectratio/  , and here: https://www.unravel.com.au/aspect-ratio-cheat-sheet  and here:
https://blog.chameleondg.com/post/111891072017/resolution-aspect-ratio-cheat-sheet

which all give the 2K square pixel resolution for 1.85:1 aspect ratio as  2048 x 1107 .  (and for 16:9 they list the number 2048 x 1152)

However, my friend put this to an editor of long-time experience and was told by the editor:
"I've always worked at 2048 x 1080 , I've never heard of the number 2048 x 1107"     Well, that set me back ... What does that mean?  

Also, in terms of 16:9  the 'Aspect Ratio cheat sheets' referred to above all give the 2K pixel resolution for 16:9/1.78:1 aspect ratio as  2048 x 1152,  however
another article I found while doing my research insists that 2048 x 1152 (for 16:9 aspect ratio) is a wrong,   ("a total crock")  , that 16:9  2K resolution is not 2048 x 1152 ,
but rather 2048 x 1080 .

http://endcrawl.com/blog/2048x1152-is-a-total-crock/

This article says:

Quote

 

    "HD masters are 1920x1080
    DCI “Scope” is 2048×858
    DCI “Flat” is 1998x1080
    DCI “Full Container” is 2048x1080

Did you notice anything there?
Deliverables are 1080 lines or less. (Always.)

If you are finishing in a 16×9 aspect ratio, and you’re finishing in “2k”, you’re actually going to deliver … 1920 × 1080. 

Likewise, if you’re finishing in 1.85  and “2k”,  your actual deliverable is 1998 × 1080.  Again, 1080 lines."

 

This is confusing.  2048 x 1107 seems to be mathematically correct for 1.85:1 aspect ratio , not 2048 x 1080 .  (or 1998 x 1080 according to http://endcrawl.com/blog/2048x1152-is-a-total-crock/ )

Likewise 2048 x 1152 seems to be mathematically correct for 16:9/1.78:1 aspect ratio .  Why would that article say "2048 x 1152 is a total crock"  ?

Can anyone clarify this for me ?   If one were going to work at 1.85:1 aspect ratio should the project be originated at  2048 x 1107  or  2048 x 1080  ?

 

 

Edited by David T. Nethery
correct a typo

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For cinema

Its 1998 x 1080 - for DCI 1.85:1 flat

The full 2048 width is only used in cinemas for the 2.39:1 aspect ratio.

The 2048 x 1080 full container is  a 1.9:1 aspect ratio , thats the actual number of pixels a 2K DLP chip has and its wider then 1.85:1. So to maximize resolution for a 1.85:1 file, it can only be 1080 pixels tall. The full hight is used and the chip is slightly wider then 1.85:1 so the sides have to be cropped down from 2048 in to 1998. 

For 2.39:1 the full width of the chip is used 2048 and its vertically cropped to 858.

Best to stick to the DCI flat standard to avoid cinemas miss framing. Also best to conform to the correct resolution initially to avoid resizing too much

If its for broadcast or web its better to 1.85:1 letterbox within 1920 x 1080 16:9 container. The DCI spec is only important if your going to make a cinema DCP. 

For 4K double the numbers

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Thanks for the reply , Phil.

What does it mean on these sites:

https://dannybribiesca.com/aspectratio/  , and here: https://www.unravel.com.au/aspect-ratio-cheat-sheet  and here:
https://blog.chameleondg.com/post/111891072017/resolution-aspect-ratio-cheat-sheet

where it gives the resolution of 1.85:1 as  2048 x 1107 ?   This is where I'm still confused. 

 

-

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2048 x 1107 is a 2K scanning/record resolution of 1.85:1, 35mm film. Since a 2K scan is going to be 2048 wide and the hight dependant on aspect ratio up to 4:3. If your producing a 35mm print, then you would master at 2048 x 1107 for 1.85:1 2K typically and laser record it to film at that resolution.

But if your mastering for digital projection, stick to the DCI spec, it assumes a 2048 x 1080 or 4096 x 2160 chip in the projector. Ideally you want to avoid resizing if possible. 

The bigger challenge is for odd aspect ratio films e,g 1.66:1 or 2:1 - they aren't coved in the DCI spec. At lot of 2:1 films are letterboxed within the 1.85:1 DCI frame - even though they "could" use more pixels by using the full width of the chip.

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