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difference between 1.85:1 and 1.89:1 aspect ratios as a deliverable

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Blase Theodore
difference between 1.85:1 and 1.89:1 aspect ratios as a deliverable
on Oct 12, 2015 at 10:15:13 pm

Does anyone have a concise history or explanation for the difference between 1.85:1 and 1.89:1?

All of our flat 2k/4k deliverables are at 1.85. However camera formats tend to lean to 1.89.

My best guess for how this happened was that older DCP specs were for 2048x1080, because thats the native projection size for 2k projectors? (Whereas current flat 2k DCI is 1998x1080.)

Can anyone clarify what happened?


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Marc Wielage
Re: difference between 1.85:1 and 1.89:1 aspect ratios as a deliverable
on Oct 13, 2015 at 4:26:42 am

Crop it to 1.85. Nobody cares. It's a couple of pixels -- let it go.

Lots and lots of cameras shoot formats for which there is no simple DCI aspect ratio. In particular, I dislike Red's 2.00:1 mode. I much, much prefer that people shoot in a format with a specific release aspect ratio in mind. For example, if they want to shoot in 4K or 5K or 6K, shoot it in 16x9 so that it's going to crop naturally and easily for a traditional HD release. If you don't, get ready for a lot of painstaking (and time-consuming) cropping and scanning.

If there's any issues with the 1.89 -> 1.85, it'll be at the top of the frame. Keep an eye on that. Don't forget that many, many distributors still request a 16x9 (1.78) version of 1.85 films. There are cable channels that expressly forbid 1.85 matted films.


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Ryan Holmes
Re: difference between 1.85:1 and 1.89:1 aspect ratios as a deliverable
on Oct 13, 2015 at 3:00:36 pm

[Blase Theodore] "Does anyone have a concise history or explanation for the difference between 1.85:1 and 1.89:1?"

Blase, there's a great video from filmmakeriq about the history of aspect ratios, though I'm not sure if it got into 1.89 vs 1.85. But it's still worth a watch if you have 15 minutes (or leave on in the background while doing something else):

Some ratios are tied to the actual sensor within the camera. So the manufacturer is just utilizing the sensor in such a way that XYZ aspect ratio comes out knowing that the post-community will pan/scan/crop and pop to make it work. Other times I think manufactures just like to troll us and see if we adapt! :-)

[Marc Wielage] "There are cable channels that expressly forbid 1.85 matted films."

And for good reason...who, outside of our industry, would understand why their widescreen TV still has black bars on the top and bottom of the frame. Grandma just bought that new 4K TV and it still has black bars?!

[Marc Wielage] "Crop it to 1.85. Nobody cares. It's a couple of pixels -- let it go. "

Marc you've been around the Cow long enough to know that there's always somebody who cares about this stuff! :-)

Ryan Holmes
http://www.ryanholmes.me
@CutColorPost


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Blase Theodore
Re: difference between 1.85:1 and 1.89:1 aspect ratios as a deliverable
on Oct 13, 2015 at 3:36:59 pm

Thanks for the input guys.

I would like to know the actual reason though. I mean the majority of camera sensors are built for 1.89. And all 2k/4k projectors are natively 1.89.

Which means that we unnecessarily lose quality twice:
First on the camera sensor, (we throw away the extra pixels.)
and then again on the projection chip (the projector only uses 1998 of its 2048, the extra projection capacity just shows black strips for the life of the projector.)

Its like the engineering community got together and ironed out the proper workflow, and then the post community ignored it.


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Tero Ahlfors
Re: difference between 1.85:1 and 1.89:1 aspect ratios as a deliverable
on Oct 14, 2015 at 4:30:41 am

[Blase Theodore] "I would like to know the actual reason though."

You should contact DCI and SMPTE.


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Milivoj Ivkovic
Re: difference between 1.85:1 and 1.89:1 aspect ratios as a deliverable
on Jun 21, 2017 at 12:19:10 pm

Has someone ever found the reasons for these weird choices in the standards? I'm curious too. Most cameras also offer recording with 1:89, probably for no other reason than it being "compatible" with that strange 2048/1080 ratio.

Is the real reason someone who made a calculation mistake, and when someone else noticed, it was already too late?



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Marc Wielage
Re: difference between 1.85:1 and 1.89:1 aspect ratios as a deliverable
on Jun 21, 2017 at 11:20:13 pm

[Milivoj Ivkovic] "Has someone ever found the reasons for these weird choices in the standards? I'm curious too. Most cameras also offer recording with 1:89, probably for no other reason than it being "compatible" with that strange 2048/1080 ratio.
"

My guess: 1.90 is the native aspect ratio of the chip, and some filmmakers are not aware that this is not an acceptable aspect ratio for final release. I think the chip makers basically decided that 1.90 was the biggest chip they could make and still get effective yields from their factory, and if you shoot with that and then crop to 1.78 -- very typical for TV -- now you have a little extra room for reframing.

The problem comes with people who don't know that and edit the entire project in 1.90 and assume that's how it's going to play on TV and in the theater. There are channels and streaming services that will take almost any aspect ratio you throw at them, but there are others that demand normal 1.85 or 1.78 or 2.39. As long as the deliverables contract says it's OK, there's no real issue.


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Joseph Owens
Re: difference between 1.85:1 and 1.89:1 aspect ratios as a deliverable
on Jun 22, 2017 at 3:17:57 pm

No one made a "math mistake."

These aspect ratios were created deliberately as disruption factors -- basically the cinema/theatre industry discriminating against 4x3 broadcast television. The video posted above doesn't go into any of the politics around how the Edison format morphed into a thicket of widescreen shapes other than as a marketing gimmick, but it was fairly deliberately chosen to make it incompatible with the small screen. And it continues.

As an industrial aside, flexible film stock begins (or began) life as a single sheet of emulsion that is longitudinally slit for the common gauges... 70mm --> 35mm --> 16mmm --> 8mm. These are just engineering approaches.

Terrific that the video finally gives Kerns Powers a shout-out for coming up with the equal-area rule that yielded 16x9.

For some fun math...take the 2 figures "16" and "9" and keep multiplying them by "2" until you come up with some other very familiar numbers. Interesting, huh?

As for the rectangularity of the image, and how much image is "wasted"; consider for a moment that all light paths through a refractive lens is circular... so you are "wasting" a ton more light on the collective square than you realize. All that even before the "overscan" that we used to deal with in broadcast television that is now under revision as "safe -action/title."

jPo, CSI

"I always pass on free advice -- its never of any use to me" Oscar Wilde.


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