Author Topic: 4:3 and 3:2 aspect ratio  (Read 17401 times)

Brawl

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4:3 and 3:2 aspect ratio
« on: September 10, 2013, 01:52:04 AM »
Can we record 1.6x crop with 3:2 or 4:3 in h264 (non raw)?

Thanks

Rewind

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Re: 4:3 and 3:2 aspect ratio
« Reply #1 on: September 10, 2013, 10:16:26 AM »
Use cropmarks like this and change the actual aspect ratio in post. This way you'll get some freedom for free )

Brawl

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Re: 4:3 and 3:2 aspect ratio
« Reply #2 on: September 10, 2013, 03:44:01 PM »
Use cropmarks like this and change the actual aspect ratio in post. This way you'll get some freedom for free )
thanks, sorry I'm a donkey in math, can you help me to understand wich resolution would be after the 1920x1080 to 4:3/3:2 crop? thx

 

Rewind

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Re: 4:3 and 3:2 aspect ratio
« Reply #3 on: September 10, 2013, 03:48:38 PM »
If you mean for 1080p, it will be:
1440x1080 for 3:4 ratio (1080 / 3 * 4 = 1440) and
1620x1080 for 3:2 ratio (1080 / 2 * 3 = 1620).

Brawl

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Re: 4:3 and 3:2 aspect ratio
« Reply #4 on: September 10, 2013, 07:01:58 PM »
If you mean for 1080p, it will be:
1440x1080 for 3:4 ratio (1080 / 3 * 4 = 1440) and
1620x1080 for 3:2 ratio (1080 / 2 * 3 = 1620).

thanks. do you know if this cropping technique can be useful for anamorphic lens? :) it sounds good.

so it does not exist a way to have more pixel in the axis of ordinate instead that less in the abscissa.

for example:

1920x1080 for 3:4 = 1920x1520
1920x1080 for 3:2 = 1920x1700

why is this possible in RAW but not in h.264? what is the technical reason?

thx a lot.

bnvm

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Re: 4:3 and 3:2 aspect ratio
« Reply #5 on: October 04, 2013, 08:35:32 PM »

why is this possible in RAW but not in h.264? what is the technical reason?

thx a lot.

Raw video works since the dev's found a way to access a 14bit data stream that gets sent to the LV. Since they have access to this data they can decide which parts and how much and the dump that data to the card. The h.264 encoding is handled by a dedicated chip that the ML dev's have no access to, they have no way of altering its behavior so they cannot enable things like croping, etc... I admit it would be nice to have for shooting anamorphic so there would be no post processing required, 3.6 aspect ratio is pretty extreme and definitely not standard.

With a 5DIII the max NON CROP resolutions are (some of these may not be continous)

4:3 = 1706x1280
3:2 = 1920x1280

5DII

4:3 = 1667x1250
3:2 = 1875x1250

With your 1.6 crop factor shooting FF that limits the width to 1200 since 1200*1.6 = 1920 so these are the max at 1.6 crop.

4:3 = 1200x900
3:2 = 1200x800

Also these are mathematically possible but may not be possible/available in the resolution choices we currently have with raw. For the 5DII has width resolutions something like 1872, 1728, 1600, 1472, 1344, etc...

I also shoot anamorphic with a Kowa 2X, as of now I have I am shooting 1472x1250 which is continuous on my 5DII, scales to 2944x1250 at a 2.35 aspect. It is only a 124% upscale to a standard 2K Cinemascope (1828x1556 2.0 PAR) size with minimal vignette with my Kowa on a 58mm Helios. It has a 1.3 crop factor at that resolution.