Remote Flash Triggers – James Allan

Introduction – Why bother?

This article is written as a “how do you do it” explanation of my technique for remote camera flash.  Please write to me if you have any tips or explanations to improve upon my article.

Most cameras come with a built in flash.    Frankly however the results are often disappointing and a bit irksome.  The flat lighting and harsh shadows make the most attractive models look pasty, unattractive and blown out.  Don’t get me wrong, there are some instances where ‘on camera flash’ is very handy.  I have used it for macro photography and fill flash and to freeze motion.

The problem is that the light is just plain unnatural.  The flash on the camera is harsh and tends to be flat.  Harsh light has sharp dark shadows as opposed to soft light which has blurry edges and less intense shadows.  Flat lighting emphasizes surface colour  as opposed to side lighting which will emphasize texture and form.  To create a more realistic effect you need to soften the light and have it come from a different direction than the camera.  

You can always use bounce flash.  The on camera flash will only fire parallel to the direction of shooting.  However a cheap flash mounted on the top of the camera can be angled up at 45 degrees so that it bounces off the ceiling.  The result is a softer more natural result.  Unfortunately not every location has a handy white ceiling.

Sometimes you just want to take the flash off the camera and position it to the side, above or even behind your subject.  To do that you need to trigger the flash with a cable, or trigger it remotely.  There are many systems for doing this.  In this article I will discuss just what I am familiar with.  That is the Nikon flash system and cactus remote triggers v6.

Some Basic concepts

The triad of exposure (shutter speed / aperture and ISO) becomes a tetrad when you use a flash, (shutter speed / aperture / ISO and flash strength) .   The flash becomes the fourth element.

There are two ways to handle exposure when you are using a flash.  Many cameras will control the flash strength according to a reading taken from the sensor.  This is called TTL or “through the lens metering”.  Alternatively you can use trial and error and adjust the flash strength and aperture manually until a successful exposure is achieved.

The Nikon flash system is designed to give TTL capacity, even when you are using multiple flashes in different locations.  It controls the flash units with preflash synchronization.

The cactus triggers on the other hand are designed for manual setting.  When you are using several flashes, it can be quite complicated to calculate the correct exposure, and sometimes the manual approach turns out to be less complicated.  The cactus triggers use radio frequency synchronization which is more reliable than the pre flash method, not requiring ‘line of sight’ between units.

Nikon flash control

The Nikon system works for many Nikon dSLR (I have D7000) working with Nikon flashes (I use SB 700).   Let me go through the steps.   

First I turn on my Nikon camera and select Manual exposure setting.  I select a shutter speed that is commensurate with the sync speed of the flash, say 1/250th of a second.  The aperture f8 and ISO 100 or 200.  Remember to turn off Auto ISO setting.  I usually save these settings as a “user defined preset” under U2.

Next I enter menu / Custom Setup (pencil) / e Bracketing – Flash / e5 Flash control for built in flash / CMD Commander Mode.  The CMD menu will open.  From this menu I can scroll through the flash on the camera as well as two groups of external flashes.  I usually like to have the on camera flash switched off – , and the external flash group A and B on TTL.  I can adjust the  relative strengths of the 3 groups of flash in the comp. column from +3 to -3 stops.  Alternatively you can adjust flash strength by moving them closer or further away from the subject.  You can change the channel setting, but I never do.  Once selected I also save these settings to “user defined preset” under U2.

Don’t forget to raise the built in flash, or you will get nothing good.

Next I turn on the flash units and move the dial around to remote.  All other settings I leave as default.

Now I can take a few test shots to see that the exposure is correct.  Amazingly it is often right first time around.  If it is too dark, I have various options.  First, I will open the aperture, say 1-2 stop.  Second I would re position the flash closer, or increase the flash strength. Third, increase the ISO by 1 stop.  If the image is too bright, I would do the reverse, close the aperture, reduce flash strength or decrease ISO.

Now you are set.  Fire away.  Feel free to adjust the position and strength of the two or more flash units to get optimal lighting of the subject.  Remember that the flash will need to recharge between firings.  If you take a shot too soon, before it has time to recharge, your photo will be underexposed or even blask.

Cactus flash triggers

The cactus system works with many brands of camera and many brands of flash.  The individual control units however have to be calibrated to the camera or flash that you are using.  You this through the menu function, and scrolling with the wheel.  I have 4 cactus v6 units.  

First step, they all need to be turned on.  That is the camera, the flash units and the Cactus units.    One cactus unit is mounted on the camera hotshoe and is set to transmitter mode.  The three speed lyte flash units are then put onto the hot shoe of  the three remaining cactus units and set to receiver mode.  The flashes are switched on in TTL mode.  A fourth flash can be placed on top of the transmitter unit.

On the camera  I use the same manual settings that I described above.  Manual exposure setting.  Shutter speed 1/250th of a second.  The aperture f8 and ISO 100 or 200.  Remember to turn off Auto ISO setting. 

Each Cactus receiver unit can be set to either A, B, C or D group by pressing a prominent button on the side of the unit.  The transmitter unit on the camera can then select and adjust the flash strength for each group individually.  You simply press the same side button as the desired flash group and roll the knob at the rear to adjust strength.  The strength can be adjusted from 0 (full strength) to 256 (8 stops below full strength).  I usually have the units firing at a mid range strength, between 8 and 32.   Using the test shot – trial and error method, as described above,  it is not too hard to get a correct exposure within a few shots.

You can turn flash groups on and off at the transmitter unit by selecting the previously described side buttons for the 4 groups.  You have the flexibility to fire one, two, three or all four flash groups.  Accordingly you can forensically analyse a lighting setup, one group at a time to see what it contributes to the setup.

Although it takes a bit longer to setup, the Cactus units provide superior flexibility and control of the lighting setup.  You can also incorporate flash units from other manufacturers, even switch to a different camera body.  Perhaps the main cost being that you lose TTL functionality of the Nikon flash system.  However the trial and error exposure method is easy to learn and quite quick when you have good control of the setup.

Managing off camera flashes

So now that we have the capacity to use several flash units in unison, what are we going to do with them?  We are now ready to enter the world of studio photography.  There is a whole science of lighting setups and different effects that can be achieved.  I do not claim to be a master.  Needless to say the basic principles are these.

Modifiers

The light from the flash will often be modified by a diffuser like a soft box, umbrella or reflector to create soft multi directional lighting.  A gel can be used to add a colour to the light, either warm (yellow, orange, red, brown) or cool (blue or green).  Alternatively a snoot or hexagon grid will create unidirectional lighting that can be restricted to certain elements of the subject, for instance to pick up hair detail or add rim lighting.

Key light

The light on the subject is often called the key light.  Classical face lighting is described by the parts of the face covered by shadow (usually from the nose).  These include side lighting (half face in shadow), Butterfly lighting (shadow below the nose), loop lighting (shadow to one side of the nose),  Rembrandt lighting (a triangular patch of light on the cheek), and the low key effects, rim lighting, and silhouette.  The shaded areas can be filled with detail by using reflectors or a secondary source of light.  If the key light dominates, the image is high key.  If the key light is minimal, low key.

Background

As well as lighting the subject, it is important to manage the background.  Usually a backdrop is used.  This can be black velvet to absorb stray light and prevent shadows.  If a white back drop is used, there will be shadows.  These can be eliminated if the backdrop is lit by a bright light (white or coloured).  The backlight needs to be overexposed in order to eliminate shadows effectively.  Sometimes a printed or painted backdrop will give atmosphere.  Often this is rendered out of focus by adjusting depth of field with a larger aperture.

Natural light

Sometimes you may wish to use a natural background.  This works best when the background is brighter than the subject.  You can control the amount of ambient light in the image by adjusting the shutter speed downwards.  Be careful to avoid double or blurred images of the subject by avoiding too much ambient light falling on the subject.

Expression

I am always mindful that the science of lighting has to be balanced by the art of animating the subject with natural but expressive posses.  Well there you have it, studio lighting in a couple of paragraphs.  Best of luck.

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