Deconstructing light, part three: balancing ambient

One of the neat things you can do when you’re controlling the light is highlighting your subject, but preserving the ambient atmosphere. Today’s post focuses on how to do that.

Ambient light is your friend: it helps you to fill in the background with pre-lit object, providing compositional context; but more importantly, you can use it to preserve the atmosphere of the scene, which can be difficult to recreate if you’re using 100% flash or strobe only. All of the previous control points for single and multiple lights apply, of course. The two major challenges with balancing ambient are exposure and color. I’ll deal with exposure first.

There’s no fixed rule for this, but the more ambient you want to preserve, the closer your exposure must be to ambient exposure; the best way to do this is by shooting in manual mode and balancing out your shutter speed and aperture until you’re around one stop underexposed; I wouldn’t do anything more than three stops of difference (unless you have very bright ambient point sources) because very little, if any, ambient sources will remain. You’ve got three parameters to play with here – shutter speed, aperture and ISO. Shutter speed should fall somewhere between your max sync speed and around 1/30s if you’re dealing with people; higher if there are moving objects, lower if static. Aperture should allow you to hold in focus whatever you need to. ISO is the remaining balancing factor once you have set the other two – try and keep this low to maintain image quality, however. I generally don’t go higher than 800. Note that flash power should be the last thing that’s altered (and done by the camera’s meter to balance out the required exposure) – this is because you are firstly setting your exposure based on ambient, then filling the primary subject with the precise amount of flash required for a proper exposure.

Color is actually simpler: if it’s daylight, or close to it, there’s no need to gel your flashes, because they operate at fairly close to daylight Kelvin temperatures. If it’s tungsten or fluorescent, you’ll need to use the correct gels over the front of the flash so they provide the same temperature color source as the ambient lighting; you’ll also then have to set the white balance in-camera to match ambient. Note that you don’t always have to match the flashes to ambient; sometimes having a bit of temperature difference isn’t a bad thing, as it can help to highlight the subject. Just don’t make the difference too glaringly obvious.

Let’s move on to the examples.

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Omega Speedmaster 9300. Nikon D800E

One of the more common situations I face where I have to balance flash and ambient are lume shots of watches – you need a very long exposure to capture the glow luminous material; often 30s at f16 ISO 100, or longer. However, a luminous dial pattern on its own isn’t very interesting, so I usually supplement this with some ambient. You could do this two ways – composite a regular (but underexposed by several stops) shot in, or just add a manual flash kicker to define the case. Here, I used 1/16th power from top left through the diffuser box.

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Sandwich. Nikon D700

The background glow is the restaurant decor; I had flashes reflecting off umbrellas left and right to illuminate the sandwich. Exposure was balanced out to expose two stops under ambient for the restaurant, with a longer exposure time and base ISO (sandwiches don’t do much moving).

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Autumn texture. Nikon D90

One flash from the left, not diffused to provide a bit of harsh light to add texture and definition to the subject; exposure 1/2 stop under ambient. I wanted to fill the shadows and create some cross-lighting effects rather than make things soft and diffuse; a very flat angle for the flash position was used to accomplish this.

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MRI room. Some of you might recognize this from a previous on assignment post. Nikon D800E

The objective of this shoot was to show the clean, high-tech environment of the hospital’s new MRI machine. The MRI and room itself had ambient lighting on both the machine and ceiling; if we shot with this alone, firstly our models wouldn’t have been able to keep still for long enough, and secondly, the ambient light was far too cool with a large difference in color temperature to the machine. Hence, flashes were used to illuminate the room and models – one in a reflective umbrella to the top right corner of the room; I needed throw and definition for the whites. The second one was placed on top of the rear casing of the MRI to fill the back of the room.

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Mammogram. Nikon D800E

Here, the client wanted to convey a warm, friendly feeling to the room; nothing says this better than warm lighting. The color temperature of the flashes were shifted with gels; the primary source source was a flash reflected off an umbrella behind and above the machine; a secondary flash was bounced off the wall behind me (and to the right of the patient) to provide fill at 1.5 stops under the main flash.

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Sony RX100 product shot. Nikon D700

The final example is one of those deceptively complex shots: one flash from top right was fired through the diffuser to light the camera body and background, but the exposure was altered until it balanced out that of the screen. If I’d just used the native sync speed of 1/250s and stopped down, the screen would black out because it isn’t that bright.

Come back again tomorrow for the final part in this series! MT

A primer on lighting equipment is here. Part one on single sources can be found here; part two on multiple sources, here.

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Visit our Teaching Store to up your photographic game – including Photoshop Workflow DVDs and customized Email School of Photography; or go mobile with the Photography Compendium for iPad. You can also get your gear from B&H and Amazon. Prices are the same as normal, however a small portion of your purchase value is referred back to me. Thanks!

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Images and content copyright Ming Thein | mingthein.com 2012 onwards. All rights reserved

Deconstructing light, part two: multiple sources

Part two deals with multiple sources: how and where do you use them? What is the one key rule to remember?

Although you can do a lot with a single flash, there’s even more that can be done with two or more. For starters, you can fill in shadows; or if you want to get more adventurous, you can mix both hard and soft light (direct and diffused) for better definition, or more accurate replication of found light sources. (There’s one particular shot I’m rather fond of that I call ‘the Hollywood’, which I’ll go into later).

There’s one critical thing to remember when using multiple sources, though: there must always be a primary source. If you don’t have one, then you won’t have any subject definition – opposing sources will fill in the shadows, and shadows are what defines the shape of an object.

The same parameters you can control with a single source apply to multiple sources, of course. The more sources you have, the more complicated things get. It’s useful to decompose your thinking thusly:
1. Primary source, on main subject
2. Secondary source, on main subject – definition (rim light, not diffused) or fill (diffused, or reflected)?
3. Other sources, for background objects or secondary subject – take steps 1 and 2 and repeat.

I’m sure you can now see why Joe McNally needs several trunks full of speedlights. I’m not quite there yet, but I find that most of the time a two-light setup is sufficient; there are times where I’ll use three for watches, but I’ve yet to require four sources (except in situations where I need more power from one location, and have to add a second flash to turn the wick up a notch).

Let’s look at some examples.

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Ferrari 250 GTO. Sadly, not a real one. Nikon D200

This one has two distinct sources, both flashes behind diffuser panels – one at left, and one at right. They’re actually slightly behind the subject to create a nice specular highlight that defines the curvature in the panels; if I’d put the sources at right angles, you’d have very flat illumination and not much of a feel for the 3-D shape of the car.

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Nikon 14-24. Nikon D3

Some objects betray their lighting secrets very clearly – reflective hemispheres are perhaps the worst culprits. For something like this, the best thing to do is keep the light source simple; in this case, two softboxes from the left and right. Power was equal; if not, you wouldn’t get the nice multi-colored reflections off the coatings on the lens. Note that the softboxes were actually pretty close to the subject; the hemispherical shape makes them appear further away.

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Lange Datograph. Nikon D700

Through a trick of optical projection, the watch actually appears floating in mid-air and truncated, even though it’s resting securely on the surface behind. Note that this was shot with the lens and watch resting on a flat surface, but lit as though vertical. The primary source was through a diffuser, aimed at the watch and shielded from lighting the lens in front; a secondary source, at reduced power, lit the nameplate of the lens; finally, a third source – again at reduced power – lit the background. A simple-looking shot, but a bugger to light.

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Panerai Arktos. Nikon D200

Sometimes you want hard definition; in such cases, a concentrated, direct source is the best way to go, without diffusion. Here, I used one flash from the top, and one from the bottom to provide fill. Both were positioned at a low angle to avoid flat-looking interference at the point of the subject closest to the camera, with a small baffle on one side of the flash preventing light spillage.

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Steak. Nikon D700

This example is an instance of when two light sources look like one. A flash with reflective umbrella was used from the top right; you actually need to see a bit of harsh reflection off the oil on the steak to know it’s a juicy steak, making a reflective umbrella ideal. However, you still need to soften out the edges a bit, which is where the very low power secondary source comes in; if it’s too diffuse, you lose the defining effect of the first source, so there’s another flash reflecting off an umbrella from the left, too.

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The Hollywood. Nikon D3

There are actually four flashes in play here: two at the back to provide the spotlight effect and backlit definition on the subject’s hair; one from the right in a softbox as the primary source, and a fourth on the D3 to serve as remote commander.

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Jaeger-LeCoultre Gyrotourbillon I. Nikon D700

Lighting at the macro scale is extremely tricky – partially because you don’t have a lot of working distance, and partially because your source has to be the right size: too large, and the light is too soft and lacks definition; too small, and you’re going to get harsh reflections and rough-looking surfaces. Here, I used one flash fairly close to the topmost diffuser, with a secondary one through the back diffuser to provide fill of the shadows – thanks to the handy aperture in the watch dial.

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Seiko Fifty-five Fathoms. Nikon D700

We finish this section with a classic two-light: primary source upper back center, and secondary fill from the left to give the transparent domed objects – water and watch crystal – some definition. Not much power difference between the two flashes; the bigger difference was the location of the flashes. The back one was further away and with a wider spread than the left one; this created a larger source of almost equal brightness.

Come back tomorrow for part three! MT

A primer on lighting equipment is here. Part one on single sources can be found here.

____________

Visit our Teaching Store to up your photographic game – including Photoshop Workflow DVDs and customized Email School of Photography; or go mobile with the Photography Compendium for iPad. You can also get your gear from B&H and Amazon. Prices are the same as normal, however a small portion of your purchase value is referred back to me. Thanks!

Don’t forget to like us on Facebook and join the reader Flickr group!

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Images and content copyright Ming Thein | mingthein.com 2012 onwards. All rights reserved