Anamorphic - Guillermo Algora - Visual Effects Compositor

Guillermo Algora
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ANAMORPHIC
Anamorphic lenses are specialized lenses used in filmmaking to achieve a widescreen aspect ratio while maximizing image quality. They produce a distinct optical effect called "anamorphic distortion. Anamorphic lenses horizontally squeeze the image onto the camera sensor or film plane. This compression allows filmmakers to capture a wider field of view while using the entire height of the frame. As a result, objects appear elongated along the horizontal axis when viewed through an anamorphic lens.
Depth of Field:

  • Shallower DOF: Anamorphic lenses tend to have a shallower depth of field compared to regular lenses at the same aperture. This means a smaller area will be in sharp focus, while the background and foreground blur more dramatically. The shallow DOF of anamorphic lenses isn't always a drastic difference. Aperture still plays a major role, and a wide aperture on a regular lens can achieve similar blur.

  • Uneven DOF: Due to their design, anamorphic lenses can have a slightly different depth of field depending on whether you're focusing horizontally or vertically. The horizontal field of view is wider, so the DOF might be shallower there compared to the vertical axis.

Bokeh:

  • Oval Bokeh: The most distinct characteristic of anamorphic bokeh is its shape. Instead of circular blur points like regular lenses, anamorphic lenses create oval or elliptical bokeh shapes, especially for out-of-focus highlights.

  • Smooth and Pleasing:  Anamorphic bokeh is often described as smoother and more aesthetically pleasing compared to regular lenses. This contributes to the distinctive "cinematic" look associated with anamorphic footage. Regular lenses create bokeh with a harsher transition between the in-focus area and the blurred background. Anamorphic lenses, due to their design, create a smoother gradient between the two. Imagine a circle (regular bokeh) transitioning abruptly into blur compared to a stretched oval (anamorphic bokeh) with a gentler transition. The oval shape itself is often found more aesthetically pleasing. Circles can appear a bit busy or distracting, whereas the elongated oval tends to blend more seamlessly with the background.

  • Anamorphic lenses can introduce anisotropic bokeh, where the shape and size of bokeh circles vary depending on their orientation relative to the horizontal and vertical axes of the frame. This anisotropic bokeh contributes to the unique aesthetic of anamorphic cinematography. Bokeh circles in regular footage are generally isotropic, meaning they have a uniform shape and size regardless of their orientation relative to the frame.

  • Bokeh circles may be more densely packed or clustered in certain areas of the frame, particularly towards the edges or corners, due to the optical properties of anamorphic lenses.

Focus Breathing:

  • The wider the aperture, the more obvious the breathing is with anamorphic lenses. Anamorphic breathing is a little different than normal spherical lens breathing where the image appears to change focal length as you rack focus. With anamorphic lenses, the amount of vertical stretching of the bokeh changes as the focus changes, so focus racks become more noticeable. As you rack focus from far to near, for example, the background gets skinnier-looking. Since stopping down the lens reduces the amount of out of focus bokeh shapes, this type of breathing is less obvious when you have more depth of field. If you shoot with an anamorphic lens at f/11, for example, there is less visible vertical stretching in the background as you rack focus. Of course, anamorphic lenses also have some breathing issues like spherical lenses where the focal length appears to change. But that is less distinctive than the vertically stretched bokeh look. It’s common to call the stretching and squashing of the background as you rack focus in anamorphic “breathing” — in fact, I’ve never heard of an alternative term for the artifact.
  • But there's a difference between the background field of view stretching or squishing because of a focus rack and the Bokeh stretching or squishing as a point source defocusses. Otherwise we could equally call an expanding out-of-focus highlight caused by a focus pull in spherical cinematography breathing, even if there was no actual change in the field of view occurring.
  • Im just saying that when most people refer to anamorphic lens breathing, like in the original post, they arent talking about regular spherical lens breathing... if they were, there would be no point in specifically mentioning anamorphic lenses.
  • When you shoot with anamorphic lenses, the effect when you rack focus is as distracting as when a spherical lens breathes badly, enough to make you minimize how often you rack focus during a scene. And the effect is similar to regular breathing in that there is a change to the image during the rack, its just that rather than a slight zoom in and out, its a vertical stretch that comes and goes. The only difference compared to spherical lens breathing is that the effect is minimized the more you stop down because less of the image is out of focus. I brought this up originally because the poster wanted to maximize the effect.
  • Well we might have to disagree that anamorphic breathing is a different thing to spherical breathing. The change in image magnification can be more pronounced in one axis with anamorphic, rather than uniform, but it's the same phenomenon, caused by lens elements shifting position relative to one another.
  • If you look at the posted tests of Lomos and Hawks above, you can see very noticeable horizontal breathing, much more distracting than any sense of vertical stretching caused by the Bokeh. From your description I suspect your experience is mainly with Panavision anamorphics, which breathe mainly in the vertical axis. However that "stretch" (or change in vertical field of view) will occur to the same degree regardless of aperture, the effect is not minimised by stopping down. The Bokeh and the breathing are two seperate things, but in the case of Panavision I can see how the vertically expanding individual elements of the Bokeh might seem part of the same effect, and draw more attention to the breathing. Stopping down a spherical lens also makes a focus pull less obvious, since there is less change in the Bokeh, but that's also unrelated to breathing.
  • Dom, I think you're technically correct and that I am conflating two separate issues which is the amount of distortion (breathing) that happens with anamorphic lenses to the background when you focus from far to near (the fact that anamorphic lenses start to compress more than 2X in the out of focus areas) and how visible that change is due to depth of field. The distortion doesn't change with f-stop but your eye notices it more when the image is very shallow in focus because of the way that the background is reduced to abstract shapes. So basically not what the other says.
Difussion and Lightwrap:

Can take on an oval or elliptical shape due to the anamorphic stretching.

Halation: Less common due to the different internal design of anamorphic lenses.
Glare: Generally less prone to flare due to the design of some anamorphic lenses.
Lightwrap: Sometimes used to describe the way anamorphic lenses can create a more immersive or "wraparound" view due to the way they capture light.

Halation: Several online resources on photography discuss the concept of halation and how it's more common in simpler lens designs [reliable source needed]. They also mention how some anamorphic lenses use internal baffling and coatings to reduce internal reflections, a key factor in halation [reliable source needed].
Glare: Information on lens design and internal reflections can be found on various optics websites [reliable source needed]. These resources explain how lens coatings and element arrangement can affect internal reflections and flare. Additionally, some sources discuss the concept of "effective aperture" in anamorphic lenses, which can contribute to less glare due to the horizontally compressed image [reliable source needed].
Lens Dirt:

Nothing to say.
Lens Sharpness:

Generally less sharp than their spherical counterparts. Reasons for this:
  • More glass elements: Anamorphic lenses use additional internal elements to achieve the wider horizontal field of view. These extra elements can introduce aberrations that reduce sharpness.
  • Wider field of view: Ultra-wide angles inherent in anamorphic lenses are inherently more challenging to design for perfect sharpness across the entire frame.
Chromatic Aberration:

Potential for increased chromatic aberration: The design of anamorphic lenses, which stretch the image horizontally, can inherently introduce more chromatic aberration compared to spherical lenses used in regular lenses.
Lens Flare:

The key difference in lens flare between anamorphic and regular (spherical) lenses comes down to the shape they produce. Anamorphic lenses produce unique lens flares characterized by horizontal streaks or lines that align along the width of the frame. These streaks are a result of the cylindrical lens elements in anamorphic lenses and contribute to the cinematic look of anamorphic footage.
Elliptical or oval shaped

Additionally, anamorphic lenses tend to produce horizontal lens flares that streak across the frame, adding to their cinematic appeal.

The elliptical flares were probably from an anamorphic lens. These lenses squash the image horizontally in order to get a widescreen picture on a standard width film strip. The anamorphic elements are usually on the front of the lens so the lens barrel appears elliptical to the camera.
Vignette:

May appear as an oval, although this unique shape can be emulated in post-production.
Lens Distortion:

  • Distortion Characteristics: Anamorphic lenses introduce specific types of distortion, notably "mumps" and "squeeze." Mumps distortion refers to a slight bulging or swelling of the center of the frame, particularly noticeable in close-up shots or when using wide-angle anamorphic lenses. Squeeze distortion occurs as a result of the horizontal compression and can affect the geometry of objects in the frame, particularly towards the edges.
  • Barrel Distortion: While anamorphic lenses are designed to minimize barrel distortion (where straight lines appear curved outward), they may still exhibit some degree of barrel distortion, especially towards the edges of the frame. However, this distortion is usually less pronounced compared to spherical lenses.


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