Anamorphic Lenses: The Key to Widescreen Cinematic Imagery

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What began as a tool and technique for capturing and projecting wider aspect ratios on 35mm film, anamorphic lenses are a runaway favorite among cinematographers for the unique characteristics they bring to moving images. Ultra-wide rectangular aspect ratios, long horizontal lens flares, and oval bokeh (the out-of-focus areas of the image) now feel as much a part of the cinematic experience as a bucket of popcorn and a liter of soda.

So how do anamorphic lenses work? The term anamorphic derives from the Greek words meaning ”formed again.” Compared to spherical lenses, which project a circular image onto the film or camera sensor, anamorphic lenses project an oval-shaped image. This is due to optical elements that squeeze more horizontal information from your scene. The captured image must then be stretched horizontally in post production, or in the projector, to be viewed at its intended aspect ratio.

Regular lens and bokeh vs. anamorphic len and bokeh

Traditionally, anamorphic lenses have a 2x squeeze, meaning that lenses capture twice the amount of horizontal information than a spherical lens. When stretched, a 2x anamorphic lens used with standard 35mm film yields a 2.39:1 aspect ratio, commonly referred to as CinemaScope, or simply "Scope." The desire for wider aspect ratios is what drove the popularity of anamorphic lenses in the film industry. In order to capture the same 2.39:1 aspect ratio with spherical lenses, it meant cropping, or ”masking” the top and bottom of each frame, thus sacrificing vertical resolution.

For digital cinematographers working in HD or 2K formats, cropping a 2K frame to get a 2.39:1 ratio leaves you with a meager 858 lines of vertical resolution. Anamorphic lenses provide a means to capture a 2.39:1 ratio without having to make that sacrifice in resolution. However, due to the wider aspect ratio of digital sensors compared to 35mm film, 2x anamorphic lenses produce a super-wide 3.55:1 ratio, with a 1.5x anamorphic lens still producing an aspect ratio of 2.66:1. To produce a traditional "Scope" ratio with a 16:9 sensor, a 1.33x or 1.35x anamorphic lens is needed.

Companies like Letus and SLR Magic have developed 1.33x anamorphic lens adapters, which attach to the front of your lens. ARRI released a version of their popular Alexa camera with a 4:3 sensor, which is compatible with 2x anamorphic cinema lenses. Lens manufacturers such as Cooke and Angénieux recently produced their first anamorphic lenses. The ultra-widescreen cinematic look is still wildly popular among filmmakers.

Whether you’re looking for streaking horizontal lens flares, made popular recently by J.J. Abrams, or you’re going for that cinematic scope aspect ratio (without losing vertical resolution), anamorphic options in the digital cinematography world are stretching new horizons and I, for one, couldn’t be more thrilled.

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With the GH4 able to use the full sensor, a 2X anamorphic adapter provides an almost perfect 2.39 aspect ratio. SLR Magic has a 2X package designed for the camera, but it is not yet available in the U.S. Email from a representative of the company said it will be in a matter of a very few weeks. Hopefully B&H will be among the first to get it.

There's one thing I don't seem to get: The anamorphot squeezes the image (and the bokeh) so that it has an oval shape. But in post we obviously want to desqueeze the image and by that we make the oval bokeh round again. It may be the case that the bokeh gets projected in a round shape through the lens and then, if desqueezed, it becomes oval but then it's wider than high (that's what I witnessed with an SLR anamorphot/Nikon SLR lens). But all the sources I could dig up promote an oval bokeh shape that's higher than wide. What am I missing here?

Unfortunately it is not possible to desqueeze the oval bokeh into round in post. Its a matter of physics. 

Actually that is exactly what these lenses do!  They squeeze the "physics" or physical properties of light, as to fit more horizontal information onto a defined physical area (the film or sensor).  The desqueezing step is to return the distorted image to a natural looking one.  Since the optics are designed to squeeze the horizontal into the vertical, as it is desqueezed you get a wider end result. If done proplery the end result should look 100% natural.  This includes the shape of the bokeh (it should look round or whatever its character is without the original squeezing).

I'm not sure if we're all on the same page. As far as I understand the oval shape of the bokeh (that still exist after desqueezing) is one of the things the anamorphic lenses are famous and sought after for.

Like here: https://i.vimeocdn.com/video/426308199_1280x720.jpg

There are even tutorials or special filters which achieve exactly that without anamorphic lenses to fake this look: http://tinyurl.com/lwnd2kv

No, that's not correct. If you look at any movies shot in CinemaScope, Panavision, etc, you will find that out of focus circles are oval, taller than wide. This is despite the fact that anything in focus has been de-squeezed correctly, so that circles are circles etc. In other words, there is a fundamental difference between the way anamorphic lenses render in-focus and out-of-focus (bokeh) parts of the image. I'm not sure why this is the case, but it's obviously true. I think it has to do with the fact that the bokeh takes the shape of the internal elements of the lens, such as the iris. For example, irises that are hexagonal will impose that shape on the bokeh. In the case of anamorphic lenses, the circular shape is distorted to a tall oval, so that's what will show up in the bokeh, despite the de-squeezing process.

You may have to look mainly at older movies to see this, because for the past 2 decades or so, many "Scope" ratio movies are produced by cropping a super-35mm image, and not by using anamorphic lenses. So the bokeh will be circular.

Actually, the ovaline shape to anamorphic bokeh is caused by the shape of the front element AND one other factor, which doubles the effect.

Let me explain.

When you shoot with a 40mm 2X anamorphic lens, you are actually shooting with a 20mm full frame equivalent....in the horizontal axis. In the vertical axis, you're still shooting 40mm. And since a longer focal length produces a shallower depth of field, you'll have a shallower depth of field in the vertical axis. Hence, ovaline bokeh.

It's true that an oval-shaped front element will give oval-shaped bokeh. But this effect is negated when the image is stretched in post. It's the depth of field that gives the FINAL shape to the bokeh.

Thank you for helping me to finally wrap my head around this!

Do you guys have kowa anamorphic lense for  BnH?

Hi Zike -

I am sorry, we do not offer KOWA anamorphic projection lenses.

Please contact us via e-mail if you have additional questions:  AskBH@BandH.com

Hello,
 I am looking for anamorphic lens for my home cinema system. The lens is to be adapted over my projector so the image projected fits the 21:9 screen
 I will appreciate very much if you could let me know  where I should be able to buy them.
 

Thanks very much

I am sorry but at this time we do not have a universal adapter that will convert a projector lens into an anamorphic lens.  If you have a specific projector model you would like us to research please e-mail HOMEAV@BHPHOTOVIDEO.COM

Generally, digitally captured images that are shot anamorphically are de-squeezed in post, prior to being projected. Thus they are projected using a standard spherical lens. When I render video that I shot anamorphically I usually put it in it's native aspect ratio. That is either 2.35:1, 2.39:1, or 2.66:1. ..without black bars or any type of letter-boxing although this may vary depending on where it is to be viewed De-squeezing during projection is solely done for film in my experience. ..no need for it when the delivery is in video format

Lenses

I don’t understand how a 2x anamorphic lens used with 35mm film produces a 2.39:1 aspect ratio. I thought the image area of 35mm film has an aspect ratio of 1.37:1. If you double that you get 2.74, not 2.39.

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