Two anamorphic lenses with the same focal length can produce very different frames. The spec that decides this is the anamorphic squeeze factor, which is how much the lens compresses the image horizontally. If you are new to the format, start with what an anamorphic lens is and how it works. This guide compares 1.33x, 1.6x and 1.8x squeeze factors, shows which recording modes each one suits, and matches each factor to lenses in the SIRUI lineup.
What Is an Anamorphic Squeeze Factor?
An anamorphic squeeze factor is the ratio by which an anamorphic lens compresses the image horizontally onto the sensor. A 1.6x lens squeezes the scene to fit a frame 1.6 times narrower. In post, you stretch the footage back out by the same ratio, a step called desqueezing, and the result is a wider frame with normal proportions.
The vertical field of view stays the same as the focal length, and only the horizontal view is multiplied. A 50mm 1.6x lens covers roughly the horizontal width of a 31mm spherical lens and the vertical view of a 50mm. This is also why the anamorphic ratio of your finished frame depends on two numbers: the squeeze factor and the shape of the sensor area you record.
The video below shows how 1.33x, 1.6x and 2x squeeze factors compare on screen.
How Does Squeeze Factor Change Your Final Aspect Ratio?
The final aspect ratio equals the recorded aspect ratio multiplied by the squeeze factor. A 16:9 recording shot through a 1.33x lens desqueezes to about 2.37:1. The same recording through a 1.6x lens reaches 2.84:1. If you match the squeeze factor to your sensor mode, you avoid unnecessary cropping.
| Squeeze factor | 16:9 recording | 3:2 / open gate | 4:3 recording |
|---|---|---|---|
| 1.33x | ≈2.37:1 | 2.0:1 | ≈16:9 (1.77:1) |
| 1.6x | 2.84:1 | 2.4:1 | 2.13:1 |
| 1.8x | 3.2:1 | 2.7:1 | 2.4:1 |
| 2x (1.6x + 1.25x adapter) | 3.56:1 | 3.0:1 | ≈2.67:1 |
Each squeeze factor has one recording mode that lands close to the common 2.39:1 cinema frame:
- 1.33x with 16:9
- 1.6x with full-frame 3:2 or open gate
- 1.8x with 4:3
Other combinations still work. They give a wider frame that you can deliver as is or crop in post, at the cost of some horizontal resolution. This is where the question of 4:3 vs 16:9 aspect ratio becomes practical. Most cameras record 16:9 by default, but whether you get 3:2 open gate or 4:3 depends on the camera model and firmware.
1.33x vs 1.6x vs 1.8x: How Does the Look Differ?
Higher squeeze factors give a more pronounced anamorphic character: more oval bokeh, more visible horizontal flares and a wider horizontal field of view at each focal length. A 1.33x lens gives a subtler version of the look. At 1.6x and 1.8x the effect is easier to see in the frame.
- Oval bokeh: After desqueezing, out-of-focus highlights are stretched vertically, and the oval shape roughly follows the squeeze factor. Ovals from a 1.8x lens look taller and narrower than those from a 1.33x lens.
- Horizontal flares: Bright light sources create horizontal streaks across the frame. SIRUI's full-frame anamorphic lenses offer a blue flare, and some series also offer a neutral flare.
- Field of view: A 50mm 1.33x lens covers about the horizontal width of a 38mm spherical lens, a 50mm 1.6x about 31mm, and a 135mm 1.8x about 75mm.
The difference between anamorphic and spherical lenses is most visible at higher squeeze factors. At 1.33x it is gentler and easier to mix with spherical footage.
Which SIRUI Anamorphic Lens Matches Each Squeeze Factor?
SIRUI offers a full-frame anamorphic lens for each squeeze factor: Astra for 1.33x with autofocus, Saturn and Venus for 1.6x, the Venus 135mm for 1.8x, and a 1.25x adapter that takes a 1.6x Venus lens to 2x.
SIRUI Astra (1.33x)
SIRUI Astra is the world's first full-frame autofocus anamorphic lens series, available in 50mm, 75mm and 100mm at T1.8. It gives about 2.4:1 from a standard 16:9 recording and suits creators who prefer not to pull focus manually.
SIRUI Saturn and Saturn V2 (1.6x)
SIRUI Saturn is a carbon fiber 1.6x series in 35mm, 50mm and 75mm at T2.9. Each lens weighs under 500g, which suits gimbal, drone and handheld work. SIRUI Saturn V2 adds a 90° switch for horizontal and vertical shooting.
SIRUI Venus (1.6x and 1.8x)
SIRUI Venus is a T2.9 manual series with blue horizontal flares and oval bokeh. The 35mm, 50mm, 75mm, 100mm and 150mm lenses use 1.6x squeeze, and the 135mm uses 1.8x, so set the desqueeze value per lens in post.
SIRUI 1.25x Anamorphic Adapter: Turning 1.6x into 2x
The SIRUI 1.25x anamorphic adapter screws onto a 1.6x Venus lens to reach a 2x squeeze (1.6 × 1.25). You set the base lens to infinity and focus with the adapter. Paired this way, the anamorphic lens adapter turns a 4:3 recording into about 2.67:1.
Which Squeeze Factor Should You Choose?
Choose based on the recording mode your camera offers and how much anamorphic character you want. 1.33x fits 16:9 cameras and autofocus workflows. 1.6x fits full-frame 3:2 or open gate. 1.8x and 2x fit 4:3 sensor modes.
| Squeeze factor | Best recording mode | Desqueezed ratio | Look | Focus | SIRUI option |
|---|---|---|---|---|---|
| 1.33x | 16:9 | ≈2.37:1 | Subtle oval bokeh, gentle flares | Autofocus or manual | Astra |
| 1.6x | 3:2 / open gate | 2.4:1 | Clear oval bokeh, blue or neutral flares | Manual | Saturn, Saturn V2, Venus |
| 1.8x | 4:3 | 2.4:1 | Stronger oval bokeh, longer flares | Manual | Venus 135mm |
| 2x | 4:3 | ≈2.67:1 | Most pronounced anamorphic character | Manual, front focus on adapter | Venus 1.6x + 1.25x adapter |
If you mainly record 16:9, 1.33x is the most direct path. If your camera supports open gate or 4:3, higher squeeze factors make fuller use of the sensor.
Final Thoughts
Squeeze factor shapes your final aspect ratio, how strong the anamorphic look is, and which camera settings you will rely on. Start from your camera's recording modes, then decide how much character the project needs. SIRUI offers a full-frame option at each step, from autofocus 1.33x with Astra to 2x with Venus and the 1.25x adapter. If you have settled on 1.6x, our side-by-side comparison of the Saturn and Venus full-frame anamorphic lenses can help you choose between the two series.
FAQ
Is a higher anamorphic squeeze factor always better?
No. A higher squeeze gives a stronger anamorphic look and a wider frame, but it needs a matching sensor mode to avoid cropping. 1.33x suits 16:9 recording, while 1.6x, 1.8x and 2x make more sense with 3:2 or 4:3 modes.
Can I use a 1.6x anamorphic lens on a 16:9 camera?
Yes. A 16:9 recording with a 1.6x lens desqueezes to about 2.84:1. You can deliver that wider frame or crop the sides to 2.39:1, which uses less of the sensor width.
Does squeeze factor change the focal length?
No. The focal length and vertical field of view stay the same. The squeeze widens only the horizontal field of view, so a 50mm 1.6x lens covers roughly the horizontal width of a 31mm spherical lens.
What is the difference between anamorphic and spherical lenses?
A spherical lens records the image without compression, so the frame matches the sensor's proportions. An anamorphic lens squeezes the image horizontally. After desqueezing, this gives a wider aspect ratio along with oval bokeh and horizontal flares.
Can the SIRUI 1.25x adapter be used on spherical lenses?
Yes. With step rings, the adapter mounts on spherical lenses and adds a 1.25x squeeze, turning a 16:9 recording into 20:9. You set the lens to infinity and focus with the adapter.
