Working with Flash | 13 |
Photography is a form of visual art that uses light to shape the finished product. The photographer may have little or no control over the subject (other than posing human subjects) but can often adjust both viewing angle and the nature of the light source to create a particular compelling image. The direction and intensity of the light sources create the shapes and textures that we see. The distribution and proportions determine the contrast and tonal values: whether the image is stark or high key or muted and low in contrast. The colors of the light (because even “white” light has a color balance that the sensor can detect), and how much of those colors the subject reflects or absorbs, paint the hues visible in the image.
As a Sony photographer, you must learn to be a painter and sculptor of light if you want to move from taking a picture to making a photograph. Most of the time, you’ll be working with available or ambient light, perhaps with reflectors or other modifiers, or even some additional continuous light sources, such as incandescent or fluorescent lamps. But at times you’ll want to turn to one of the most versatile sources of illumination you have available, the brief, but brilliant snippets of light we call electronic flash. This chapter will show you the differences between working with continuous illumination and working with flash and explain how to use the flash capabilities of the Sony a7 IV.
Flash sometimes gets a bad rap, but that’s usually prompted by photographers who make poor use of the capabilities electronic flash offers. In some respects, working with continuous lighting instead is easier and more predictable. Conventional lighting is exactly what you might think: uninterrupted illumination that is available all the time during a shooting session. Daylight, moonlight, and the artificial lighting encountered both indoors and outdoors count as continuous light sources (although all of them can be “interrupted” by passing clouds, solar eclipses, a blown fuse, or simply by switching off a lamp). Indoor continuous illumination includes both the lights that are there already (such as incandescent lamps or overhead fluorescent lights indoors) and fixtures you supply yourself, including photoflood lamps or reflectors used to bounce existing light onto your subject.
On the face of things, electronic flash may be uncomfortably different from what we are used to, and sometimes considered difficult to use. In practice, you can use flash in all the same ways you use continuous lighting to shape your images, and, in some cases, take advantage of its special properties, such as its action-freezing short duration. Electronic flash is notable because it can be much more intense than continuous lighting, lasts only a brief moment, and can be much more portable than supplementary incandescent sources. It’s a light source you can carry with you and use anywhere.
Of course, your Sony a7 IV does not have a built-in flash of any sort. There are several reasons for that. The company wanted to make the a7-series cameras exceptionally compact, and a built-in flash would have added bulk. In addition, even though Sony upgraded the size and power of the a7 IV’s NP-FZ100 battery, the features of the camera alone do a good job of consuming all that extra juice during a shooting session. With a camera like the a7 IV, a pop-up flash (which most advanced photographers would likely use only as fill or to trigger off-camera units wirelessly) would provide an unacceptable amount of extra drain. So, any electronic flash used with these cameras is necessarily an external flash with its own power supply, which happily solves the power drain situation while reducing red-eye and other effects of on-camera flash.
Before moving on to discussing flash in detail, here’s a quick comparison of the pros and cons of continuous illumination versus flash:
Until you delve into the situation deeply enough, it might appear that serious photographers have a love/hate relationship with electronic flash. You’ll often hear that flash photos are less natural looking, and that on-camera flash in most cameras should never be used as the primary source of illumination because it provides a harsh, garish look. Some photographers strongly praise available (“continuous”) lighting while denouncing electronic flash.
As I noted at the beginning of this chapter, that bias is against bad flash photography. Indeed, flash—often with light-modifying accessories—has become the studio light source of choice for many pro photographers. That’s understandable, because the light is more intense (and its intensity can be dialed up or down by the photographer), freezes action, frees you from using a tripod (unless you want to use one to lock down a composition), and has a snappy, consistent light quality that matches daylight. (While color balance changes as the flash duration shortens, some Sony flash units can communicate to the camera the exact white balance provided for that shot.) And even conservative photographers will concede that electronic flash has some important uses as an adjunct to existing light, particularly to fill in dark shadows.
The electronic flash you use will generally be connected to the camera by slipping it onto the hot shoe or linked by a cable connected to an adapter mounted on the shoe. In all cases, the flash is triggered at the instant of exposure, during a period when the sensor is fully exposed by the shutter.
The a7 IV has electronic shutter options, which I’ll describe later, and a conventional vertically traveling physical shutter that consists of two curtains. The front curtain opens and moves to the opposite side of the frame, at which point the shutter is completely open. The flash can be triggered at this point (so-called front-curtain sync, which is the default mode), making the flash exposure. Then, after a delay that can vary from 30 seconds to 1/250th second (or 1/320th second in APS-C mode), a second, rear curtain begins moving across the sensor plane, covering up the sensor again. If the flash is triggered just before the rear curtain starts to close, then the optional rear-curtain sync is used. In both cases, though, a shutter speed of 1/250th-1/320th second is (ordinarily) the maximum that can be used to take a photo, because that’s the speed at which both the front and rear curtains are tucked out of the way, leaving the entire full frame exposed to capture the flash burst.
Figure 13.3 illustrates how this works, with a fanciful illustration of a generic shutter (your a7 IV’s shutter does not look like this). As an exposure is made using the conventional (non-electronic) shutter, the curtains move as follows:
Keep in mind that the a7 IV always defaults to front-curtain sync unless you explicitly select another sync mode using the Fn button or the Exposure/Color > Flash > Flash Mode entry.
If you’ve absorbed that, things are about to get really interesting. There are three settings not found in the Exposure/Color > Flash group that affect how you use flash. They reside in the Shooting > Shutter/Silent group, and include options in which either the physical front curtain or both the physical front curtain and the rear curtain are simulated electronically. Only one of these three electronic modes can be used with flash in still photography. Here’s the difference:
Using a shutter speed faster than the maximum sync speed can cause problems. Triggering the electronic flash only when the shutter is completely open makes a lot of sense if you think about what’s going on. To obtain shutter speeds faster than 1/250th-1/320th second, the a7 IV exposes only part of the sensor at one time, by starting the rear curtain on its journey before the front curtain has completely opened. That effectively provides a briefer exposure as the slit of the shutter (the distance between the front and rear curtains) passes over the surface of the sensor. If the flash were to fire during the time when the front and rear curtains partially obscured the sensor, only the slit that was actually open would be exposed.
You’d end up with only a narrow band, representing the portion of the sensor that was exposed when the picture was taken. For shutter speeds faster than the top sync speed, the rear curtain begins moving before the front curtain reaches the bottom of the frame. As a result, a moving slit exposes one portion of the sensor at a time as it moves from the top to the bottom. Figure 13.4 shows three views of our typical (but imaginary) physical focal plane shutter. At left is pictured the closed shutter; in the middle version you can see the front curtain has moved about 1/4 of the distance down from the top; and in the right-hand version, the rear curtain has started to “chase” the front curtain across the frame toward the bottom.
If the flash is triggered while this slit is moving, only the exposed portion of the sensor will receive any illumination. You end up with a photo like the one shown in Figure 13.5. Note that a band across the bottom of the image is black. That’s a shadow of the rear shutter curtain, which had started to move when the flash was triggered. Sharp-eyed readers will wonder why the black band is at the bottom of the frame rather than at the top, where the rear curtain begins its journey. The answer is simple: your lens flips the image upside down and forms it on the sensor in a reversed position. You never notice that, because the camera is smart enough to show you the pixels that make up your photo in their proper orientation during picture review. But this image flip is why, if your sensor gets dirty and you detect a spot of dust in the upper half of a test photo, if cleaning manually, you need to look for the speck in the bottom half of the sensor.
I generally end up with sync-speed problems only when shooting in the studio, using studio flash units rather than my Sony dedicated unit. That’s because if you’re using either type of “smart” flash, the camera knows that a strobe is attached, and remedies any unintentional goof in shutter speed settings. If you happen to set the a7 IV’s shutter to a faster speed in Shutter Priority or Manual mode, the camera will automatically adjust the shutter speed down to the maximum sync speed as soon as you attach and turn on an external flash (or prevent you from choosing a faster speed if the flash is powered up). In Aperture Priority or Program mode, where the a7 IV selects the shutter speed, it will never choose a shutter speed higher than 1/250th-1/320th second when using flash.
But when using a non-dedicated flash, such as a studio unit plugged into a PC/X adapter plugged into the camera’s multi-interface shoe, the camera has no way of knowing that a flash is connected, so shutter speeds faster than 1/250th-1/320th second can be set inadvertently.
Note that the a7 IV can use a feature called high-speed sync that allows shutter speeds faster than the maximum sync speed with certain external dedicated Sony flash units. When using high-speed sync, the flash fires a continuous series of bursts at reduced power for the entire duration of the exposure, so that the illumination is able to expose the sensor as the slit moves.
High-speed sync is a function of the flash unit and not the a7 IV. It is set using the controls that adjust the compatible external flash units, which include the HVL-F60M/RM, HVL-F58AM, HVL-F56AM, HVL-F45RM, HVL-F28RM, HVL-F43AM/HVL-F43M, HVL-F32M, and HVL-F36AM. (Note that all flashes ending in AM use the older Minolta-style foot and cannot be mounted on the a7 IV without an inexpensive Sony ADP-MAA adapter.) High-speed sync cannot be used when working with multiple flash units. When active, the message H appears on the LCD panel on the back of the flash. You’ll find complete instructions accompanying those flash units.
The difference might not seem like much, but whether you use front-curtain sync (the default setting) or rear-curtain sync (an optional setting) can make a significant difference to your photograph if the ambient light in your scene also contributes to the image. At faster shutter speeds, particularly 1/160th second, there isn’t much time for the ambient light to register, unless it is very bright. It’s likely that the electronic flash will provide almost all the illumination, so front-curtain sync or rearcurtain sync isn’t very important.
However, at slower shutter speeds, or with very bright ambient light levels, there is a significant difference, particularly if your subject is moving, or the camera isn’t steady. In any of those situations, the ambient light will register as a second image accompanying the flash exposure, and if there is movement (of the camera or subject), that additional image will not be in the same position as the flash exposure. It will show as a ghost image and, if the movement is significant enough, as a blurred ghost image trailing in front of or behind your subject in the direction of the movement.
As I mentioned earlier, when you’re using front-curtain sync, the flash goes off the instant the shutter opens, producing an image of the subject on the sensor. Then, the shutter remains open for an additional period (which, as I’ve noted, can be from 30 seconds to 1/250th-1/320th second). If your subject is moving, say, toward the right side of the frame, the ghost image produced by the ambient light will produce a blur on the right side of the original subject image, making it look as if your sharp (flash-produced) image is chasing the ghost. For those of us who grew up with lightning-fast superheroes who always left a ghost trail behind them, that looks unnatural (see Figure 13.6).
So, Sony provides rear-curtain sync to remedy the situation. In that mode, the shutter opens, as before. The shutter remains open for its designated duration, and the ghost image forms. If your subject moves from the left side of the frame to the right side, the ghost will move from left to right, too. Then, about 1.5 milliseconds before the rear shutter curtain closes, the flash is triggered, producing a nice, sharp flash image ahead of the ghost image.
Another flash synchronization option is slow sync, which is actually an exposure option that tells the a7 IV to use slower shutter speeds when possible, to allow you to capture a scene by both flash and ambient illumination. To activate Slow Sync, press the Fn button, navigate to the flash options, and choose Slow Sync. Or, make the same selection from the Flash Mode entry in the Exposure/ Color > Flash group.
Then, the exposure system will try to use longer shutter speeds with the flash, so that an initial exposure is made with the flash unit, and a secondary exposure of subjects in the background will be produced by the slower shutter speed. This will let you shoot a portrait of a person at night and, much of the time, avoid a dark background. Your portrait subject will be illuminated by the flash, and the background by the ambient light. It’s a good idea to have the camera mounted on a tripod or some other support or have SteadyShot switched on to avoid having this secondary exposure produce ghost images due to camera movement during the exposure. (See Figure 13.7.)
Because Slow Sync is a type of exposure control, it does not work in Manual mode or Shutter Priority mode (because the a7 IV doesn’t choose the shutter speed in those modes). It is not disabled in those modes: you can still select it using the Exposure/Color > Flash > Flash Mode entry or Function menu, but your shutter speed will not be changed.
Calculating the proper exposure for an electronic flash photograph is a bit more complicated than determining the settings by continuous light. The right exposure isn’t simply a function of how far away your subject is, even though the inverse square law I mentioned does have an effect: the farther away the subject is, the less light is available for the exposure. The a7 IV can calculate distance if you’re using lenses with a distance encoder chip, which detects the position of the focusing mechanism as focus is locked in just prior to exposure. The component transmits this information to the camera, which can use it to determine the distance to the subject, and, therefore, much flash output is required to illuminate the scene. This Advanced Distance Integration (ADI) delivers high-precision flash metering that is unaffected by the reflectance of subjects or backgrounds.
But, of course, flash exposure isn’t based on distance alone. Various objects reflect more or less light at the same distance so, obviously, the camera needs to measure the amount of light reflected back and through the lens. Yet, as the flash itself isn’t available for measuring until it’s triggered, the a7 IV has nothing to measure.
The solution is to fire the flash twice. The initial shot is a pre-flash emitted by the flash mounted on the camera a fraction of a second before the main flash burst. If you are using multiple off-camera flashes, the pre-flash from the on-camera commander tells each of the remote flash units to emit a pre-flash of their own.
The camera analyzes the illumination it receives from the initial pre-flash bursts to calculate the amount of light needed for a correct exposure, taking into account, if necessary, any ambient light also present in the scene. Then, the main flash is emitted, at the calculated intensity needed to provide a correct exposure. The appropriate power needed is also communicated to the off-camera flash. As a result, the primary flash burst(s) may be a longer total duration for distant objects and shorter duration for closer subjects, depending on the required intensity for exposure. This through-the-lens evaluative flash exposure system uses distance information, and it operates whenever you have attached a Sony dedicated flash unit to the a7 IV, and a lens that provides the necessary distance integration information.
Note that you can bypass the a7 IV’s TTL autoflash exposure entirely and set some flash for Manual Flash (M) mode, in which you can select a power output level (from 1/1 to 1/128th power). You’ll need to calculate exposure manually, but this DIY exposure makes it easy to set up your own flash ratios. One flash can be set to 1:1, and additional flashes triggered wirelessly can be adjusted to provide 1/2, 1/4, 1/8, or another reduced amount of illumination.
You may also have Manual/Multi mode for multiple-shot “strobe” bursts. With Multi, you can select the frequency of flashes, from 1 to 100 Hz (flashes per second). You can also specify the total number of flashes to emit, from 2 to 100, plus “- -,” which tells the flash to keep strobing at the frequency you selected, which is useful for exposures longer than one second. The power output level for each flash can be set from 1/8th to 1/128th power in 0.5 or 0.3 stop increments. If High-Speed Sync is deactivated on the flash, an additional 1/256th power level is available. You can calculate an appropriate shutter speed by dividing the number of flashes by the flash frequency. That is, 20 flashes at 5 flashes per second require a shutter speed of four seconds. You can use this multiple-exposure feature creatively, or, more practically, say, to analyze your golf swing. Check your flash’s manual to see how Multi is implemented with your unit.
When using Still photography mode, there are several flash modes available in the Exposure/Color > Flash group and Flash Mode setting in the Fn menu:
This is a feature discussed previously in Chapter 3. It’s important to keep in mind how the camera’s exposure compensation system works when you’re using electronic flash. To activate exposure compensation for flash, visit the Flash Comp. entry in the Exposure/Color > Flash group, and set the amount of plus or minus compensation you want. (See Figure 13.9.) This function is not available when using Intelligent Auto mode. When you find that your flash photos are too dark even after you have set the highest amount of compensation, then the flash simply cannot provide more power; you must move closer to the subject, use a wider aperture, set a higher ISO, or take all of these steps. Note too that when a subject is extremely close to the camera, even a –3 setting may not prevent an excessively bright image. You’ll probably have to reduce your ISO setting in that case.
Flash exposure compensation affects only the amount of light emitted by the flash. If you want to adjust the brightness of the ambient-light exposure, you would also need to use the conventional exposure compensation feature. In fact, you can use both features at the same time, to get a brighter subject and a darker background, or vice versa. Let’s say you’re taking a photo of a friend posing against a light-toned background such as a white cabana on a beach. A plus exposure compensation setting (perhaps +1 when using multi-segment metering) will ensure that the cabana won’t be underexposed while a –1/3 or –2/3 flash exposure compensation will ensure that shadows on your friend’s face will be lightened by a very gentle burst of flash. This is an advanced technique that requires some experimentation but can be valuable when used with some expertise.
When using semi-automatic or manual exposure modes, red-eye reduction is available if Red Eye Reduction is On in the Exposure/Color > Flash group (as described in Chapter 6). The flash will fire a burst before the photo is actually taken as you depress the shutter release button. That will theoretically cause your subjects’ irises to contract (if they are looking toward the camera), thereby reducing the red-eye effect in your photograph. This feature works only with a flash attached to the camera directly; it is not available when Wireless Flash is enabled.
As I write this, Sony offers nine accessory electronic flash units that are compatible with the a7 IV’s multi-interface shoe. Four of them are triggered optically, that is, by pre-flashes that are emitted before the shot to communicate exposure and setting information between the camera and flash unit. Those are the HVL-F60M, HVL-F43M, HVL-F32M, and HVL-F20M.
In addition, there are five units that can be triggered optically or by more versatile radio-wireless communication. They are the HVL-F60RM/HVL-F60RM2, HVL-F46RM, HVL-45RM, and HVL-F28RM. All these external units can be mounted on the camera, connected to the camera’s multiinterface shoe with a cable (I’ll detail how later) or (except for the HVL-F20M) used off-camera with wireless connectivity when triggered by another external flash used as a controller/master. Each can also function as the controller/master mounted on the a7-series camera to trigger other flash units wirelessly.
Also, there are earlier Sony flash units designed for the older Minolta/Sony proprietary hot shoe. They can be used with the a7-series cameras if you purchase an inexpensive adapter, such as the Sony ADP-MAA (about $25). Or, you can skip the adapter and use wireless-compatible legacy flash units off-camera in wireless mode, triggered by an on-camera master/controller. Although they are discontinued, I’ll describe some of these earlier flash units because you may already own one or can find one used at a price that’s hard to resist. I don’t recommend the legacy flash/adapter approach, because older units operate using a more limited communication protocol, which I’ll describe later. But because some of you may have an older flash or can pick one up used at a decent price, it doesn’t make sense to pretend that these discontinued models don’t exist, because they still can work with your a7 IV, especially as remote/receiver units.
Sony also offers radio trigger/receivers: the FA-WRC1M, which can trigger any of the radio-capable flashes when mounted on the a7 IV’s multi-interface shoe, and the FA-WRR1 receiver, which has its own hot shoe on which you can mount a non-radio Sony flash to give it radio control.
Before I describe the flash units themselves, there are a few aspects you need to understand in order to compare electronic flash. If you’re a veteran Sony (or Minolta) shooter, you can skim over this section, or skip it entirely. Those new to photography or the Sony realm should find this information useful.
The first thing you need to learn when comparing flash units is that Sony incorporates the Guide Number (GN) of each flash in the product name. So, what’s a Guide Number? The GN designation derives from the good old days prior to automatic flash units and through-the-lens flash metering, when flash exposures had to be calculated mathematically. Those days are very long ago, indeed, as Honeywell introduced Auto/Strobonar flash units way back in the 1960s.
Guide numbers are a standard way of specifying the power of a flash when used in manual, nonautoexposure mode. Divide the guide number by the distance to determine the correct f/stop to use at full power. With a GN of 197 at ISO 100, you would use an aperture of around f/19.7 for a subject that’s 10 feet from the camera (197 divided by 10), or around f/9.5 for a subject at a distance of 20 feet. Because most countries in the world use metric measurements, guide numbers are given using values for both meters and feet. Thus, Sony’s HVL-F60M/RM unit has a guide number of 60/197 in meters/feet, and the 60 GN is incorporated into the unit’s product name.
The Guide Number data is most useful for comparing the relative power of several flash units that you’re considering. According to the inverse square law, a flash unit with a GN of 200 (in feet) puts out four times the amount of light as one with a GN of about 100. If your accessory flash has a zoom head, which can change coverage to match the focal length setting of your lens, the GN will vary according to the zoom setting, as wider zoom settings spread the same light over a broader area than a telephoto zoom setting.
Starting in 1988, Minolta phased in a proprietary hot shoe, the so-called iISO shoe, which was supposedly more rugged and secure than the original ISO 518 shoe, based on a design that dates back to 1913, when it was used to attach viewfinders to a camera (electronic flash hadn’t been invented yet). No other vendors, including Canon and Nikon, embraced Minolta’s design and continued to use the industry standard shoe. The ISO 518 standard doesn’t specify any electronic connections between camera and flash, other than the “dumb” triggering circuit, so when sophisticated electronic flash units with TTL metering and other capabilities were developed, each vendor created their own hot shoe version with the necessary electrical contacts for their cameras and flash units. The chief consequence for non-Minolta/Sony shooters was that you could mount dedicated flash units from one brand onto the ISO 518 shoe of another vendor’s camera, and trigger that flash in manual, non-TTL mode.
When Sony purchased Konica Minolta’s camera technology it began redesigning legacy features, and the old iISO hot shoe came under scrutiny. In 2012, Sony introduced a 21+3-pin hot shoe which it dubbed the multi-interface shoe, which resembles a standard ISO 518 hot shoe with its “dumb” contacts. However, tucked away at the front of the shoe are additional electrical contacts that allow intelligent TTL flash metering communication between the camera and flash, and much more. For example, a whole series of stereo microphones from Sony and others, designed to plug into the multi-interface shoe, are available. As I noted earlier, you can purchase adapters that allow you to connect older iISO flash to the a7 IV, or to attach new-model flash units to a camera that has the original iISO hot shoe.
In some cases, you can get your external flash off the camera without using a wireless connection by linking an HVL-F60M/RM and a7 IV with a physical cable. The gear needed for the hook-up can be costly, so I don’t recommend it, but if you want to go that route, here’s the way to go. Purchase the Sony FA-CS1M multi-interface shoe adapter (about $40). It slides into the a7-series camera’s multi-interface shoe and has a four-pin TTL socket on the front. Connect that socket to a matching four-pin outlet located on the underside of the HVL-F60M/RM, beneath a protective terminal cap, using a 4.9-foot FA-MC1AM cable ($60). If you need more length, the FA-EC1AM extension cable ($50) adds another 4.9 feet to your connection. The HVL-F43M does not have the four-pin socket and connecting it to a cable requires some additional adapters, so you’re better off not going that way.
There are three Sony top-of-the-line flash units readily available, the HVL-F60M, HVL-F60RM, and HVL-F60RM2. They are similar in output and operation, with some differences:
These are the most powerful units the company offers, with an ISO 100 guide number (GN) of 60 in meters or 197 in feet at ISO 100. As I noted earlier, the GN does not indicate actual flash range but it’s useful when comparing several flash units in terms of their general power output. They are all priced in the $550-$600 price range.
Like all Sony multi-interface shoe flash units except the HVL-F20M, the F60M/F60RM/F60RM2 automatically adjust the zoom head to vary the angle of coverage to suit the lens focal length in use. You can zoom the head manually instead, if you prefer. A built-in slide-out diffuser panel boosts wide-angle coverage so it’s suitable for photos taken at short focal lengths with the 10-18mm zoom. There’s also a slide-out “bounce card” that can reflect some light forward even when bouncing the flash off the ceiling, to fill in shadows or add a catch light in the eyes of your portrait subjects. The dust- and moisture-resistant units use four AA batteries but can also be connected to the FA-EB1 ($250). The new pack is compatible with the 46RM, F60M, and F60RM/RM2 units and is capable of accepting either four or eight AA batteries in replaceable magazines, for up to 660 flashes with speedy recycle times of 0.6 seconds. When connected to the flash, it becomes the unit’s primary power source. You may find the FA-EB1AM available at reduced prices, which has room for 6 AA batteries for increased capacity and faster recycling.
Regardless of power source, the F60M/RM/RM2 automatically communicate white balance information to your camera, allowing the a7 IV to adjust white balance to match the flash output. It also offers a dedicated video light that can be useful for a bit of extra illumination if the subject is close to the camera. When you point the flash head upward, the trio of LED video illuminator lamps are revealed. You can use these large units as a main flash or allow them to be triggered wirelessly by another compatible flash unit. A pre-flash burst of light from the triggering master/controller unit causes a remote flash unit to fire. When using flash wirelessly, Sony recommends rotating the unit so that the flashtube is pointed to the location where light should be directed, while the front (light sensor) of the flash is pointed toward the camera. In wireless mode, you can control up to three groups of flashes, and specify the output levels for each group, giving you an easy way to control the lighting ratios of multiple flash units.
This is a smaller, less powerful version of the HVL-F60RM. Like its sibling, it can be used as a radio commander or receiver, but in optical mode only as a receiver triggered wirelessly by an optical master. It’s priced at $400, like the HVL-F45RM (described next).
If you want an on-camera flash capable of triggering external flash units optically and by radio control and are intimidated by the price of the HVL-F60RM, this flash is an affordable ($400) option. It also can be triggered wirelessly by an optical master, by another HVL-F45RM or an HVL-F60RM mounted on the a7 IV, or by the Sony FA-WRC1M Wireless Radio Commander mounted on the camera. When using radio control, it uses 14 channels to communicate with up to 15 flash units in five groups. It has a guide number of 45/148 (meters/feet) at ISO 100, and a fast 2.5-second recycle time. Its zoom head adjusts for the field of view from 24mm to 105mm (perfect for the a7 IV’s kit lens) and has an LED video light.
This less pricey ($328) electronic flash (shown in Figure 13.11) shares many of the advanced features of the HVL-F60M/RM/ RM2 but has a lower guide number of 43/138 (meters/feet). Features shared with the high-end unit include HSS, automatic white balance adjustment, and automatic zoom with the same coverage of focal lengths and the slide-out diffuser, as well as a built-in bounce card. Its quick-shift function allows you to direct the flash upward or to the side by rotating the head. This unit also can be used in wireless mode as a master/controller or remote/slave, and it also offers the quick-shift bounce feature. The HVL-F43M is light (at 12 ounces) and runs on four AAs. This flash replaces the similar HVL-F43AM unit, which uses the older iISO hot shoe.
The $270 HVL-F32M is a low-cost wireless-compatible electronic flash unit. It features a high-speed synchronization mode, wireless control, and automatic white balance compensation. In wireless mode, it can be used only on Channel 1 (as I’ll describe shortly) but can function as both a master/controller and remote/slave. The flash is powered by a pair of AA batteries and it is resistant to both dust and moisture. Those who love to use bounce flash will like the built-in bounce sheet and retractable wide-angle panel that spreads the light to cover the equivalent of a 16mm lens.
A most welcome addition to the Sony flash line is this highly affordable ($250) external flash that helps bring radio control within the reach of less well-heeled Sony users. (See Figure 13.12.) It can operate as either a radio commander mounted on your a7 IV, or as a remote triggered by another RM-series flash or the FA-WRC1M wireless radio commander (which I’ll describe later in this chapter). It has a guide number of 28/92 (meters/feet) and sports a compact size that makes it a perfect companion for the a7 IV whether used alone or with additional Sony flash units. The tilting flash head is adjustable from 0 to 120 degrees for bounce control. You can buy one of these to start out your kit, knowing that it will be fully compatible with additional Sony radio-controlled flash units as you expand your arsenal. Manual power settings from 1/1 to 1/256th power are available. Repeating flash is possible at rates up to 10 per second for 40 flashes, and the HVL-F28RM supports slow-sync, high-speed sync, and front- and rear-curtain sync.
The least-expensive Sony flash (see Figure 13.13) is the HVL-F20M ($150), designed to appeal to the budget conscious, especially those who need just a bit of a boost for fill-flash, or want a small unit (just 3.2 ounces) on their camera. It has a guide number of 20 at ISO 100, and features simplified operation. For example, there’s a switch on the side of the unit providing Indoor and Outdoor settings (the indoor setting tilts the flash upward to provide bounce light; with the outdoor setting, the flash fires directly at your subject). This flash can serve as a master/controller on the a7 IV to trigger off-camera flash units wirelessly but cannot be used as a remote/ slave flash. There are special modes for wide-angle shooting (use the built-in diffuser to spread the flash’s coverage to that of a lens with a very wide field of view or choose the Tele position to narrow the flash coverage to that of a 50mm or longer lens for illuminating more distant subjects). While it’s handy for fill-flash, owners of a Sony a7 IV camera will probably want a more powerful unit as their main electronic flash.
Because the Sony a7 IV lacks a built-in flash, in order to sync a flash wirelessly using optical triggering, you’ll need to own at least two compatible flash units, such as the HVL-F60M/RM, HVL-F45RM, HVL-F28RM, HVL-F43M, HVL-F32M, or HVL-F20M. One flash will be connected to the camera through the multi-interface shoe and serves as the commander flash or controller. A second (and additional) flash unit can be triggered wirelessly with optical signals, with full exposure control. It is a limited range (about 16 feet) but a useful unit if you want your primary illumination to come from the off-camera flash, and, perhaps, use a less powerful on-camera flash as the master. In that mode, the HVL-F20M makes a workable controller/master, especially since it is the least-expensive Sony flash unit. But keep in mind that it cannot be used as a remote/slave flash unit.
To use wireless flash with optical triggering, just follow these steps (I’ll address radio control later):
Here are some key concepts you must understand before jumping into wireless flash photography:
To specify the channels and remote groups used by each flash in optical mode, you must use the flash unit’s controls and menu system. As an introduction to what’s involved, I’m going to list the procedures for two of the most commonly used flash, the HVL-F60M/RM and HVL-F43M. For the HVL-F45RM and other Sony wireless-compatible flash units, consult the manual furnished with your strobe.
To choose the group on the HVL-F60M, just follow these steps:
To choose the channel on the HVL-F60RM, just follow these steps:
To choose the group on the HVL-F43M, just follow these steps:
To choose the channel on the HVL-F43M:
Once you’ve set up one or more flash for the RMT group, and one or more for the RMT2 group, you can adjust the ratio used between them.
Just follow these steps when using the HVL-F43M as the controller or remote/slave. Remember that all flashes in all remote groups must be set to the same channel, as described previously:
CTRL RMT RMT11 : 1 : 1
Just follow these steps when using the HVL-F60M/RM as the controller or remote/receiver. Again, all flashes in all remote groups must be set to the same channel, as described previously:
Your Sony electronic flash communicate with each other using optical control, via the pre-flashes emitted before the actual exposure takes place. That type of linking requires line-of-sight communication between master and remote units and works only over limited distances. Early in 2016 Sony introduced its wireless radio commander/receiver duo, which gives you a much greater range, many more channels to work with, and more control. Unfortunately, Sony’s radio control solution is expensive, making it impractical for all but the most avid (and well-heeled) shooters. I expect it will be more popular among professionals who can justify the expense, and those, such as photojournalists, who need the flexibility of a larger number of channels to avoid conflicts with other photographers covering the same event. To properly equip yourself, you’ll need:
Each commander transmitter can support up to 15 receivers in any combination of flash units and remote cameras, with your choice of 14 different channels (reducing those conflicts at the next Olympics you cover in 2024). All the devices on a particular channel can be divided up among as many as five different groups, so you could conceivably have a dozen or more flash units spread among all those groups to provide very sophisticated lighting effects, over a range of more than 98 feet (30 meters).
But wait! There’s more. The HVL-F60RM, HVL-F46RM, HVL-F45RM, HVL-F28RM, and FA-WRC1M wireless radio commanders give you Manual, TTL, and Group control of flashes, and power adjustment from full power (1/1) to 1/256th power in 1/3-stop increments. The 3.3-ounce commander and 3-ounce receiver each run on two AA batteries. While I don’t expect to see many a7 IV owners springing for this system, it’s nice for ambitious photographers to know that these capabilities are there for them to grow into. Eventually, Sony will introduce additional radio-capable flash units and commanders, probably at more affordable prices.
3.21.104.183