diffuser – Ming Thein

Deconstructing light, part four: continuous sources

October 1, 2012 by Ming Thein

The final part in this introduction to lighting mini-series is a look at when continuous light sources can be useful, and how to best deploy them.

I use continuous lighting primarily for food photography – specifically, large, high-CRI LED panels – because the low temperature of the source doesn’t interfere with the subject. (Try blasting sashimi with flash repeatedly, and you’ll soon see just how fast delicate fish can cook.) However, it’s also useful in other situations – obviously, to give clients an idea of what the end result will look like; for videography, when flashes obviously aren’t feasible, and less obviously, when you’re working in a dark environment and actually need a reasonably accurate representation of what the light will look like in order to compose and focus.

The rules for using continuous lights are pretty much the same, but with a few limitations:
1. Color temperature usually isn’t variable, and for large sources, you might not be able to find gels big enough – so you will probably have to go with almost 100% artificial light in your exposure. Note that you can also find continuous tungsten lights, but these run very hot and have a very low color temperature, which can lead to problems with blues.
2. LED panels aren’t that bright, so you will need to work with a tripod, and again, watch ambient light – it will creep in because the exposure times will necessarily be longer than for flash photography.
3. Subject motion – another consequence of longer exposures, especially with human subjects.
4. Heat. If you’re using tungsten light, be careful with things accidentally coming in contact with the bulbs or heads and catching fire or burning. That includes your skin.
5. Power. You’ll need to be plugged into mains or large batteries for lights of any consequential power. Ensure you take this into account when planning for a shoot – extension cables and power strips are your friend!

Let’s look at some examples, shall we?

The end of sorbet. Leica D-Lux 5

Single small LED panel to the top; note the hot spot on the spoon. The problem with using panels is that they’re difficult diffuse without a significant loss in power; the only way to make it work is either live with the hot spots (not a major problem for food) or get bigger panels (very expensive). I wanted my panels to be versatile, so I’m now using 45x45cm models.

Test shot from the M-Monochrom review. Leica M-Monochrom, 50/2 APO

One large LED panel off to the right; since it was a test shot, I didn’t bother to clear the wire from the foreground…with human subjects, LED panels enable faster, more comfortable working as you don’t have to make as many trial and error adjustments with the flash, and it’s simply not as hot.

Bread. Leica D-Lux 5

Part of a series from a food photography class I ran for Leica earlier in the year. I had two small LED panels for this, spread out around the top of the image and on even power; they provided definition and shadow. Image was shot top-down, obviously.

Foie gras. Leica D-Lux 5

Two LED panels; one top left, one top right. Both slightly above the subject to highlight that moisty, oily sheen on the seared foie gras. LED panels are quite directional but yet with short throw; this means they’ve got to be fairly close to your subject, and you’ll need more than one to fill in the shadows.

Leica S2, using the D-Lux 5

This is an example of what you can do when you have 40 LED panels at your disposal – I demonstrated product photography using the mini-panels to create a ring of light around the subject, with some actually providing light on the subject, and some just there to provide background texture.

Sushi platter. Leica D-Lux 5

One medium panel from the top took care of lighting here – getting the height and angle right is the critical part, so that the subject is evenly lit but yet has definition to preserve the shape and texture of the fish. Panels were about 30cm above the subject in this case.

Rice cones. Olympus OM-D

I used two panels here – one on full power from the right side, slightly elevated relative to the plane of the plate, and slightly behind; the other was to the left and running 1/8th power to provide fill and keep the food looking fresh and ‘bright’ rather than shadowy and ‘heavy’. Lighting is all about psychology and creating the desired mood in the viewer…

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

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Filed Under: On Photography Tagged With: continuous source, deconstructing, diffuser, flash, how to, lighting, ming, ming thein, mingthein.com, speedlight, thein

Deconstructing light, part three: balancing ambient

September 30, 2012 by Ming Thein

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.

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.

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).

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.

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.

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.

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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Filed Under: On Photography Tagged With: balancing ambient, deconstructing, diffuser, flash, how to, lighting, ming, ming thein, mingthein.com, speedlight, thein

Deconstructing light, part two: multiple sources

September 29, 2012 by Ming Thein

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.

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.

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.

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.

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.

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.

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.

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.

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.

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Filed Under: On Photography Tagged With: balancing ambient, deconstructing, diffuser, flash, how to, lighting, ming, ming thein, mingthein.com, speedlight, thein

Deconstructing light, part one: one light

September 28, 2012 by Ming Thein

Over the next few days, we’ll look at a few examples of lighting, and specifically, deconstructing it: what lights were positioned where, and what was the logic of doing so?

Today, I’m going to start with some relatively simple setups: they only use one light, with or without additional modifiers. Quite often, you don’t actually need much more than that. Single light setups tend to have very well defined shadows and highlights; chiaroscuro is the term that’s used to refer to an image that is predominantly described by it shadows and negative spaces. Classical painters were masters of this technique; they lit things in ways that are very difficult to replicate in real life – partially because of the size of their sources, and partially because they weren’t strictly limited by the laws of physics.

For simplicity, let us assume that you’re shooting at your camera’s highest sync speed, and that ambient light is not really a factor into the equation. Note that everything said here applies to both speedlights and studio strobes. I’m not going to discuss built in or on-camera flash, because it simply will not give you the results you need or offer the flexibility required. There are few variables in a one-light setup:

1. Output power
How bright do you want it? Usually, your lights will alter power based solely on your desired depth of field – which translates into aperture, which in turn translates into the amount of power required to provide a correct exposure. Note that the shutter speed only affects ambient light, not the power output of the flash. Flash duration is often 1/1000s or even much shorter. Most cameras will sync to 1/250s or thereabouts; this is the maximum duration of a full power flash. Those that sync at higher speeds require the flash to fire several times to cover the focal plane, as this is the highest speed at which the entire sensor area is exposed at the same time. (Anything faster, and the opening between shutter curtains is effectively a narrow moving slit.)

2. Distance
More distance requires a higher guide number to provide the same given illumination. Distance also affects the perceived size of your source – in general, providing the light isn’t a single point, the farther away you are, the brighter your source has to be for a given illumination level. For more diffuse light, you want your primary source to be further away.

3. Beam coverage/ angle
Most flashes and heads can have their beam angle changed – you want to match the beam angle to the focal length to produce the optimal balance frame coverage and power consumption; lighting more than you need to is a waste of power, but less than your angle of view will produce hot spots. Of course, you could always do this deliberately for a spotlight effect. Note that a wide beam close to the subject and diffuser will not look the same as a spot (telephoto setting on the flash) beam farther away with a big diffuser; the latter will produce far softer light.

4. Diffusion
The best example of diffusion is the difference between a clear, cloudless day and an overcast one: look at the difference in shadows. A cloudless day produces very harsh shadows and wide dynamic range with high brightness in the highlights; it’s a dynamic range nightmare (especially for outdoor wedding shooters, because of all that black and white involved). The opposite is true for cloudy days – note how soft and diffuse the light is. The clouds are effectively adding as a diffuser. For photographic/ flash purposes, you can use a diffuser – not a small clip-on thing that goes on your flash, but something larger like a softbox. The further away your source is from the diffuser, the softer the light is going to be. Control diffusion, and you effectively control the subject’s tonal differentiation.

5. Angle of incidence/ positioning
This seems obvious, but where you put your light and how you aim it can make a huge difference to the look of the image. In fact, it’s possible to leave the orientation of subject and camera fixed in one position, and just move your lights to create several completely different-looking images.

A quicks note on color and white balance: assuming all of your exposure comes from flash, just set your white balance to flash or daylight – most cameras will do this automatically. We do need to start worrying about mixed color temperatures, but only when balancing ambient and artificial light.

Let’s look at some examples.

Hair. Leica X1

Single speedlight in softbox; shot at 1/2000s sync speed – to freeze motion, I used a camera with a leaf shutter and high flash sync speed. The source was positioned at 45 degrees to the subject and camera to provide definition; it was not that far away from the subject to avoid too much diffusion – this way, you still get some highlight definition which helps give the subject shape.

Maitres du Temps Chapter 3 prototype dial. Nikon D800

Single speedlight behind diffuser panel to the top of the watch. The watch was inside a diffuser box to control reflections of surrounding objects off its polished surfaces. For images like this, the precise position of the flash relative to the diffuser and subject, as well as the beam angle, are very important – a small change in the position of the flash or beam angle changes the nature of the reflection significantly, as you will see demonstrated by the next image. For this image, the source was reasonably high up, far away, and with a wide beam angle to produce a soft reflection.

Lange Datograph. Nikon D700

This shot employed an almost identical setup to the previous one, except the flash was at a lower angle, much closer to the watch and with a tighter beam spread (longer zoom setting). Note how the reflection in this shot is very concentrated in one spot close to the top edge of the crystal, and is much ‘harder’ and more defined than in the previous shot.

Seasoning. Nikon D700

I used a flash in an reflective umbrella to the back left of the subject here; I wanted some diffusion but also some definition – too much diffusion and the pasta looks like a flat, matte amorphous blob. The source was partially behind the subject to provide a bit of backlight, which would define the grains of seasoning against the dark background of the person’s shirt. Note: there is such a thing as too much diffusion!

Girard-Perregaux F1-047. Nikon D700

Despite appearances, this shot actually employed direct flash with almost no diffusion. The watch itself is fairly matte, and the texture of the carbon-fiber dial is only apparent when struck with strongly directional light. I used a single flash to the right of the subject, almost touching the diffuser panel; this provided a minimal amount of softening of the edge of the flash source (so it wouldn’t appear as a hard point source in the minor reflections) but enough directionality to give the dial definition.

Prawns. Nikon D700

This example involves one flash again, but bounced off an umbrella fairly far away from the subject. Given that the room, tablecloth and surroundings were predominantly white, any light source used would reflect and provide some fill. This meant that the primary source had to be diffuse, yet directional – making an umbrella ideal.

Eugenie. Nikon D200

The final example involves a combination of light modifiers – a snoot and a diffuser box. The snoot was used to concentrate the light to the center of the diffuser; the diffuser was used to soften the skin of the subject. The net effect was a soft spot – imagine a source about the size of a large dinner plate, with intensity dropping off towards the edges. Thus, we get the best of both worlds – chiaroscuro definition, and gentle tonal rolloff in the shadows and highlights.

Come back tomorrow for part two. MT

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