Anamorphic squeeze factor explained

What "squeeze factor" means

An anamorphic lens uses a cylindrical element to squeeze the scene horizontally onto the sensor. A 2x lens fits twice the horizontal field of view into the same sensor width. A 1.33x lens fits a third more. In post, or on a monitor with a desqueeze function, you stretch the image back by the same factor.

desqueezed aspect ratio = sensor aspect ratio × squeeze factor

So the right squeeze depends on the sensor area you record:

• 16:9 + 1.33x ≈ 2.36:1. Very close to 2.39:1 scope with almost no crop, which is why 1.33x is popular on mirrorless cameras recording 16:9.
• 3:2 + 1.6x = 2.4:1. Sirui says this about its 1.6x full-frame lenses, and it is the main reason for the 1.6x format. On 16:9 the same lens gives about 2.84:1, which you can crop.
• 4:3 + 2x ≈ 2.67:1, usually cropped to 2.39:1. This is the classic film-era combination, and the reason cinema cameras offer 4:3 and 6:5 modes.
• 16:9 + 2x ≈ 3.56:1. Very wide, so you throw away a lot of the frame to reach 2.39:1.

Squeeze and the look

A higher squeeze means more anamorphic character: more oval bokeh and longer horizontal flare streaks. Flare colour depends on the lens coating, not the squeeze. A lower squeeze gives a subtler look and keeps more of a 16:9 sensor. Horizontally, an anamorphic lens frames like a shorter spherical lens: focal ÷ squeeze. Sirui, for example, describes its 35 mm 1.6x as about a 22 mm horizontal equivalent. Vertically, framing stays the same as the marked focal length.

Common combinations