The Venetian Blind Problem

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darkcorner

If you’ve ever tried to light a scene like this and found it frustrating and difficult, we have something in common.

This still from The Dark Corner (1946) is classic ‘noir’ lighting, often imitated, rarely well. It seems like it would be simple – until you try it. The old noirs, like this one, were lit in a very particular way – with a single very bright source at some distance from the set. Note the consistency of the angles of light in the foreground and background. The smaller the light source (the more closely it approximates a ‘point source’) the crisper and clearer the shadows. The farther away (and smaller) the source is, the more like a point source it is but also the flatter and more evenly spread the beam is, contributing more to clean, crisp shadows. Outside of a stage with wild walls and big lights this is difficult to accomplish.

A word about lighting. When you google ‘noir lighting’ you’ll find a lot of resources that more or less give the same recipes. Obviously they recommend ‘hard’ light and usually recommend Fresnel fixtures as ‘small, hard lights’. While it’s true that you can make shadows with Fresnel lights, you may be disappointed by the results, especially if you’re looking for crisp, deep shadows and clean highlights. It becomes even more difficult in small spaces – apartments, residences, offices – and we’ll go into detail about how to address that in this post.

Although Fresnel fixtures are the most common and easily available hard lights, there are others, Lekos and HMI’s for example. Lekos use commercially produced patterns called ‘gobos’ (‘go before optics’) and are specially designed to throw those patterns cleanly. The problem is that gobo patterns are very ‘stagey’ – fine in a theatrical context when the audience is actively suspending disbelief but the look doesn’t translate well in film.  They don’t do any better than fresnels with patterns that don’t fit in a gobo holder.

A light with a parabolic reflector like an HMI will not throw clean shadows because of the reflector but you can strip a fixture like a Joker 800 down to the bulb and it’s great for noir effects.. Make sure you leave the safety glass beaker on the globe and try it. I will post photos when I can get to it.

If you drop a cookie (from ‘cuculoris’, a device for casting shadows or silhouettes to produce patterned illumination) six feet in front of a standard fresnel pointed at a wall 16 feet away, chances are you’ll get something that looks like this. It’s probably not what you were hoping for.

arri16-10

Figure 1.

There are shadows, yes, but they’re not very pretty, not crisp or well defined and worse, the shadows are doubled. The doubling of the shadows is not a design flaw of the light, it reflects (literally) the fundamental design of halogen Fresnels and is common to nearly all of them in varying degrees. In other words it’s not a bug, it’s a feature that happens to interfere with what we’re trying to do. There is a quick way to minimize these shadows (which my colleague Andy instantly theorized from Fresnel fixture design, noted in Tungsten Fresnels) but in application, well, it’s a little like Voodoo.

Without getting deeply into the physics or explanation, it goes like this: take something like a paint stir stick, hold it vertically and move it slowly side to side directly in front of the light until the secondary shadows disappear. There should be a point at which the secondary shadows are gone or minimized but the output of the light is basically the same. The optimum width of the blocking instrument may well be different for every light but the technique should work for any Fresnel light that creates secondary shadows.

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Figure 2. The Voodoo Stick setup will look something like this.

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Figure 3. The effect of the Voodoo Stick will be something like this. Not perfect but better. Compare with Figure 1.

New LED Fresnel lights are designed differently with different kinds of reflectors and may not have this exact issue (further research required). The shot above (Fig. 1) was made with an Arri 650, sixteen feet away from the wall, with a venetian blind cookie six feet from the light (ten feet from the wall) – exactly the way many online sites recommend to do ‘noir’ lighting.

This is what the basic setup looked like.

setup

Figure 4.

There are a number of important factors at play here. It’s all about relative distances – the distance of the light from the cookie and the distance from the cookie to the projected surface (the wall). The more salient in this case is that the relative distance of the cookie from the projection surface makes a huge difference to the clarity of the shadow thrown. The closer the cookie (or the object throwing the shadow) is to the projection surface and the greater the distance from the light, the crisper the shadow will be. If we put the cookie at six feet, instead of ten, we get a shadow that looks somewhat better:

arri16-6

Figure 5.

Obviously, however, the need to place a cookie so close to the projection surface is an issue with film. This placement would create lots of problems with blocking, framing and camera movement. Let’s pick an arbitrary minimum distance of cookie to wall of ten feet to allow for blocking talent, camera movement, etc. This is a bare minimum but assuming we’re working in small spaces that’s probably all we’re going to have with any distance between the light and the cookie.

There is only one light I’ve worked with so far that handles this situation well right out of the box, the Altman 65Q, which I have covered in another post. At a distance of sixteen feet from the projection surface, with a distance of six feet from the cookie (a distance of ten feet from cookie to wall), the Altman looks like this:

altman16-10

Figure 6.

There is no doubling and a crisp, clean shadow. Compare with the photo using the Arri 650 in Fig. 1 and the Arri with the Voodoo Stick in Figure 3.

The Altman 65Q, however, is an unusual light and may be difficult to get your hands on, especially with the snoot/barndoor attachment (which really helps). Originally designed for stage and retail display work, it has been largely supplanted by other instruments. If you’re looking to rent one, a theatrical rental house is probably a better bet than a film rental house. The Altman saves you the trouble of the Voodoo Stick manipulations (which are a little unpredictable) but may be more difficult to find, especially on short notice or on location.

Ok we have some basic shadow work happening, but is there any way to improve it? Yes, and it’s all about mirrors.

There are three different kinds of mirrors – planar (plane), convex and concave. Eventually I’ll go into much more detail in another post about the different kinds of mirrors and how you can use them. For this subject we’re going to stick with plane mirrors. A plane mirror is what you look at to see an accurate reflection – a ‘normal’ mirror.

Earlier in this post I noted that the distance between the light source and the cookie was an important factor in the qualities of the projected shadow. The farther away the light source, the smaller it is and the ‘flatter’ and more evenly spread the light is. Mirrors can help us do that. The diagram below shows how a plane mirror can dramatically increase that distance with a minimal footprint:

mirror-diagram

Figure 7.

Here (again) is the Arri 650 shooting straight through the cookie at 16 feet with no Voodoo Stick action:

arri16-10

Figure 1.

and here is the Arri 650 shooting via the mirror through the cookie (a functional distance of 26′ instead of 16′)

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Figure 8. Note that there is still doubling of the shadows, although improved.

This is the Arri 650 with the Voodoo Stick via the mirror at a functional distance of 26 feet.

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Figure 9.

Here (again) is the Altman 65Q shooting straight through the cookie at 16 feet:

altman16-10

Figure 6.

And here is the Altman 65Q shooting via the mirror through the cookie (a functional distance of 26′ instead of 16′)

altmanmirror26-10

Figure 10.

Now we’re getting somewhere. There are several ways to improve your shadow projections. Using a standard Fresnel fixture, a Voodoo Stick will quickly help you minimize double shadows. A Plane Mirror will give you greater relative distance, reduce the apparent size of your light source, give you crisper shadows and by itself reduce doubled shadows. An Altman 65Q will spare you the problem of working with doubled shadows in the first place, give you the crispest possible shadows with the best contrast and is a very versatile light to have in the kit.

Can you do better than this for a noir effect? Yes, but it will probably require either building your own lighting instruments or radical surgery on existing ones. That’s another post (Return of the Venetian Blinds).

In a final note, one thing you may notice in the illustrations above is what I call the ‘enlarger problem’. You’ll see that in the examples where the light is bounced on the mirror and is, effectively, 26 feet away (Figures 8, 9  and 10) that the cookie appears almost ‘normally’ sized. When the lights project directly through the cookie, the blinds and leaves are noticeably larger (Figures 1 and 6). This effect is also a function of the relative distance between the light and the cookie. When we see late afternoon sunlight throwing a shadow of window panes on the wall, we don’t see ‘enlargement’ of the window shadow but when we try to imitate it with a light, we do.

The sun is far enough away (roughly 93 million miles) that by the time it hits our window the divergence of the beams is minimal in the space it takes to hit the living room wall. The beams from a light only 16 feet away, however, are still hell bent on getting as far away from each other as they can as fast as they can. There’s nothing wrong with enlargement, just keep in mind that you are indicating time of day and the kind of light by the shadows you throw. If the beam rapidly spreads and enlarges the shadow – it’s artificial light and probably night. If the shadows are not enlarged much then it’s sunlight. Unless you have big lights to work with and a lot of space, imitating sunlight will probably require miniature cookies. This (and more) will be covered in detail in another post.

 

 

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