Time Up for Tungsten?

Poppy Drayton, in “The Little Mermaid”, lit by a tungsten 1K bounced off poly

Last October, rental house VMI retired all of its tungsten lighting units as part of its mission to be a Net Zero company by 2030. I know this mainly because I am currently writing an article for British Cinematographer about sustainability in the film and TV industry, and VMI’s managing director Barry Bassett was one of the first people I interviewed.

Barry is very passionate about helping the environment and this is reflected in numerous initiatives he’s pioneered at VMI and elsewhere, but in this post I just want to discuss the tungsten issue.

I love tungsten lighting. There’s no better way to light a human face, in my opinion, than to bounce a tungsten light off a poly-board. (Poly-board is also terrible for the planet, I’ve just learnt, but that’s another story.) The continuous spectrum of light that tungsten gives out is matched only by daylight.

Dana Hajaj lit by another tungsten 1K bounced off poly

Tungsten has other advantages too: it’s cheap to hire, and it’s simple technology that’s reliable and easy to repair if it does go wrong.

But there’s no denying it’s horribly inefficient. “Tungsten lighting fixtures ought to be called lighting heaters, since 96% of the energy used is output as heat, leaving only 4% to produce light,” Barry observed in a British Cinematographer news piece. When you put it that way, it seems like a ridiculous waste of energy.

Without meaning to, I have drifted a little away from tungsten in recent years. When I shot Hamlet last year, I went into it telling gaffer Ben Millar that it should be a tungsten heavy show, but we ended up using a mix of real tungsten and tungsten-balanced LED. It’s so much easier to set up a LiteMat 2L on a battery than it is to run mains for a 2K, set up a bounce and flag off all the spill.

Shirley MacLaine lit by a tungsten book-light in “The Little Mermaid”

I admire what VMI have done, and I’ve no doubt that other companies will follow suit. The day is coming – maybe quite soon – when using tungsten is impossible, either because no rental companies stock it any more, or no-one’s making the bulbs, or producers ban it to make their productions sustainable.

Am I ready to give up tungsten completely? Honestly, no, not yet. But it is something I need to start thinking seriously about.

Time Up for Tungsten?

What is a French Over?

Film industry jargon isn’t shy of national references. A Dutch angle is a canted shot. To Spanish a piece of kit is to get rid of it (a corruption of “it’s banished”). To German a light – I think – is to lie the stand horizontal, attach the head, then raise the whole thing vertical. Or maybe that’s Italianing. I forget. But what is a French over?

It’s a type of over-the-shoulder shot. It requires the two characters to be bodily facing in the same direction, like on a bench or in the front seats of a car. If the camera shoots from behind their bodies, it’s a French over. Here are a few examples.

“Norman” (2010, DP: Darren Genet)
A commercial shot by Patrick O’Sullivan
“À bout de souffle” (1960, DP: Raoul Coutard)

A French over feels a little more conspiratorial or voyeuristic than a standard over. It gives the viewer a sense that they’re privy to a confidential conversation.

It works well for bench scenes because benches often have nice vistas in front of them which you can keep in the background of your close-ups, and you don’t have to cross the line to do a wide shot behind the bench showcasing the whole view.

“Mission: Impossible – Rogue Nation” (2015, DP: Robert Elswit, ASC)

It’s far easier to shoot French overs in a car because the operator can simply sit on the back seat rather than trying to jam the camera onto the dashboard.

French overs allow the editor more flexibility too. A typical problem of covering dialogue scenes where characters are facing the same way is that you can often clearly see the foreground character’s mouth, which locks the editor in to maintaining lip-sync every time they cut. In a French over you only see the back of the foreground character’s head so this problem is eliminated.

They’re not to everyone’s taste though. You certainly see less of the actors’ faces than in a standard over, and if the cast are not going to turn to look at each other very often their emotions could easily end up unreadable. If that’s not the effect you want, standard overs would be a better choice.

What is a French Over?

5 Things You Didn’t Know About the Iris in Your Lens

Inside a lens, amongst the various glass elements, is an ingenious mechanism which we call the iris. Just like your biological iris, it controls the amount of light passing through the pupil to form an image. I’ve written about the iris’s use to control exposure before, and its well-known side effect of controlling depth of field. But here are five things that aren’t so commonly known about irises.

 

1. f-stops and the entrance pupil

This image shows the exit pupil because it’s seen through the rear element of the lens. A view through the front element would show the entrance pupil.

The f-number of a lens is the ratio of the focal length to the diameter of the aperture, but did you know that it isn’t the actual diameter of the aperture that’s used in this calculation? It’s the apparent diameter as viewed through the front of the lens. A lens might have a magnifying front element, causing the aperture to appear larger than its physical size, or a reducing one, causing it to appear smaller. Either way, it’s this apparent aperture – known as the entrance pupil – which is used to find the f-number.

 

2. No-parallax point

The no-parallax point of a lens is located at its entrance pupil. Sometimes called the nodal point, although that’s technically something different, this is the point around which the camera must pan and tilt if you want to eliminate all parallax. This is important for forced perspective work, for panoramas stitched together from multiple shots, and other types of VFX.

 

3. Focus

If you need to check your focal distance with a tape measure, many cameras have a handy Phi symbol on the side indicating where the sensor plane is located so that you can measure from that point. But technically you should be measuring to the entrance pupil. The sensor plane marker is just a convenient shortcut because the entrance pupil is in a different place for every lens and changes when the lens is refocused or zoomed. In most cases the depth of field is large enough for the shortcut to give perfectly acceptable results, however.

 

4. Bokeh shape

The bokeh of a 32mm Cooke S4 wide open at T2 (left) and stopped down to T2.8 (right). Note also the diffraction spikes visible in the righthand image.

The shape of the entrance pupil determines the shape of the image’s bokeh (out of focus areas), most noticeable in small highlights such as background fairy lights. The pupil’s shape is determined both by the number of iris blades and the shape of their edges. The edges are often curved to approximate a circle when the iris is wide open, but form more of a polygon when stopped down. For example, a Cooke S4 produces octagonal bokeh at most aperture settings, indicating eight iris blades. Incidentally, an anamorphic lens has a roughly circular aperture like any other lens, but the entrance pupil (and hence the bokeh) is typically oval because of the anamorphosing effect of the front elements.

 

5. Diffraction spikes

When the edge of an iris blade is straight or roughly straight, it spreads out the light in a perpendicular direction, creating a diffraction spike. The result is a star pattern around bright lights, typically most visible at high f-stops. Every blade produces a pair of spikes in opposite directions, so the number of points in the star is equal to twice the number of iris blades – as long as that number is odd. If the number of blades is even, diffraction spikes from opposite sides of the iris overlap, so the number of apparent spikes is the same as the number of blades, as in the eight-pointed Cooke diffraction pictured above right.

5 Things You Didn’t Know About the Iris in Your Lens