July 31, 2017

Practical Optics 4 - Anamorphic Test Videos

Anamorphic video examples and comparisons of spherical and anamorphic images.

Benjamin B

This post features 2 videos of the comparisons of spherical and anamorphic images discussed in my previous post: Practical Optics - An Introduction to Anamorphic. I recommend reading that post in conjunction with this one.

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1. TEST A - Spherical versus Anamorphic

In our first test we compared 3 sets of spherical (on the left, indicated by an orange S) and anamorphic lenses (on the right, indicated by a yellow A) at the same distance to our subjects. The spherical lenses have angles of view similar to anamorphic lenses with twice the focal length. For example S 27 (a 27mm Primo spherical lens) has about the same horizontal angle of view as A 50 (a a 50mm Primo anamorphic).

TEST A - Comparing Spherical and Anamorphic Lenses -thefilmbook

2. TEST A - Video

Two things to note in the video above:

- The difference in circular bokehs in spherical and oval ones in anamorphic, and more generally the quality of the out of focus image. The luminous bokehs are an obvious indication of what’s happening to the entire soft focus image. Everything that is out of focus is elongated vertically. The more things are out of focus, the more they are stretched vertically, from Benoît standing at the camera in A-50 to the Millennium camera in A-100, to Adrien’s face in A-135, which has become almost abstract.

- The different quality of the rack focus in spherical and anamorphic, which is especially evident in longer focal lengths. The anamorphic focus shift changes an object in frame from an oval to a circle, or the other way around. Some filmmakers find this transformation distracting. For others it can be very satisfying cinematic transition when accomplished by a talented 1st AC.

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3. TEST C - Lens Flares

We placed a 200W Arri HMI PAR, and a Donner LED Spotlight and rotated each one to see what flares they created as they shone into the lenses. Our results reflected the unpredictability of flares created by the complex interactions of light with the lens coating, elements and iris.

TEST C - Spherical and Anamorphic flares

Anamorphic lenses are subject to flares partly because the glass in the front element offers a target for stray light beams on the set. The anamorphic squeeze also tends to give flares a horizontal shape.

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4. TEST C - Video

Two things to note in the video above:

-- The horizontal purplish “blue line” in A 50 is characteristic of the Primo anamorphic lenses. The “blue line” is a good example of how the artifacts of anamorphic have entered into the cinematic vocabulary. This linear flare was introduced with the Primo Anamorphics in the 1980s and is associated with nighttime sequences in dozens of action movies. The blue line has now come to signify an action sequence, and some filmmakers seek to create them just to convey the genre.

-- On the spherical lenses, we found that our lights tended to create an over-all glare, with occasional overlapping flare shapes. The anamorphic lenses tended to give us more lines.

-- The final image with a rear anamorph is shot with a Primo Anamorphic 11 to 1 zoom. Here the light bulbs create rectangular bokehs -- characteristic of rear anamorphs -- and the out of focus areas are closer to spherical lenses than anamorphics. This anamorphic zoom is created by adding an anamorphic element to the back of a spherical zoom, which opens to T2.8. The addition of the rear element reduces the maximum aperture to T4.5.

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