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โAnamorphic Shot Setup
As you open a shot in SynthEyes, it is important to correctly set the Anamorphic Squeeze ratio value on the Shot Setup panel. (You should do this before adjusting the pixel aspect ratio.)
The anamorphic squeeze ratio is a fundamental property of the anamorphic lens itself, indicating how much the lens squeezes the image in the horizontal direction, compared to the (nominal) vertical size. Typical anamorphic squeeze values are 2.0, 16/9 (1.778), or 4/3 (1.333); other values such as 1.5 or
1.55 may also be found. Youโll have to get this from the shot notes!
Tip: You can enter the value into the spinner as a fraction (16/9) for best accuracy; it will do the math.
As you set the squeeze ratio, SynthEyes will adjust the pixel aspect ratio to match, as in most cases the cameraโs pixels have 1:1 physical aspect ratio, therefore the (virtual) pixel aspect ratio is the same as the anamorphic squeeze.
This is not necessarily the case, however: sometimes images will be resampled after the fact to have a 1:1 virtual pixel aspect. Pixel aspect and anamorphic squeeze ratio are not necessarily the same. Anamorphic squeeze must be set correctly, even if the image has been resampled to square pixels.
For example, a 3840x2160 image with a 4:3 anamorphic lens might be resampled to 5120x2160 with 1:1 pixels for post-production purposes. The anamorphic squeeze must still be set to 4/3, while keeping pixel aspect at 1.0.
After youโve set the squeeze ratio and pixel aspect, you should see the correct finale (โvirtualโ) image aspect ratio listed. For best accuracy, donโt enter an image aspect ratio, allow it to be computed. If you must enter it, use the corresponding fraction, ie 16/9 or 16/9*4/3.
You should also set the sensor size, based on the cameraโs physical sensor specifications in the selected imaging mode. Many cameras use only a portion of their sensor, depending on the mode. In the simplest case, a 3840x2106 camera set to a 2.37 widescreen mode will only be using 1620 pixels vertically, ยพ of its QHD vertical sensor size. A true 4K camera in QHD mode will use only 93.75% of its horizontal size, etc. Youโll have to work that out if you expect to come close to barrel lens focal lengths later (which arenโt terribly accurate anyway) using the Lens\True Field of View script.
Note that if youโre 100% sure the lens is oriented accurately to 0.000โฐ, then the squeeze ratio wonโt matter, it will be compensated for by the lens parameters, and compositing pipelines will be simpler. But itโs best not to count on that.
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