Rudy Winston
Rudy Winston

Rudy Winston has over 16 years experience with Canon USA's Pro Products team, and has been responsible during that time for training Canon's staff on new products, creating presentations for customers and dealers, numerous writing projects, and providing technical assistance to professional and amateur photographers.

Metered Manual Flash Exposure with EOS-1D series

January 25, 2013

Once set, the amount of flash illumination won’t change unless the shooter changes it

We’ll start this article by saying, “bet you never knew you had this feature”, if you own a top-of-the-line Canon EOS-1D series camera. With one or more Canon EX-series speedlites, EOS users who prefer manual flash exposure can take a spot meter reading of flash, right in the camera, and set manual flash exposure in precise, 1/3-stop increments. This feature, which has been in EOS-1D and EOS-1Ds cameras since the original EOS-1D camera of 2002, makes manual flash exposure a quick and reliable alternative to E-TTL automatic exposure. We’ll explain how it works, what Canon EOS equipment it works with, and perhaps most importantly, why you might consider using it.

Why manual flash exposure?

E-TTL automatic exposure with Canon speedlites is a superb system for many flash situations, whether a shooter is working with a single flash on-camera, or using multiple flashes off-camera. Automatically adjusting flash duration and using readings from a fresh pre-flash reading before each shot is taken, it provides very accurate exposures in most circumstances, even when using light modifiers, bouncing off of walls or ceilings, and so on. For moving subjects, E-TTL flash will adjust itself for each new picture — so even a fast sequence of shots can be taken with each being adjusted individually as the flash-to-subject distance changes. Flash shots can be taken at almost any lens aperture the photographer desires, and flash exposure adjusts on-the-fly for each exposure. And, E-TTL automatic flash exposure makes it super-easy to achieve balanced fill-flash, both in daylight outdoors, and in low-light conditions as well.

However, for all its benefits, one characteristic of any automatic, through-the-lens exposure metering system which reads reflected light is that it is at least somewhat dependent upon how reflective — that is, how light or dark — the primary subject or scene is. Flash Exposure Compensation, or deliberate lightening/darkening of a flash exposure, is often needed when taking pictures of subjects that are lighter or darker than “average”. Beyond that, another characteristic of automatic flash is that it will tend to shift final exposure brightness slightly from shot to shot, since a new, fresh exposure reading is taken before each picture. For a sequence of shots of the same subject, with only minor composition changes, this can be a disadvantage in the eyes of critical professional shooters.

Manual flash control, of course, locks the flash into firing at a user-defined amount of power — full power, or fractional power levels (1/2 power, 1/4 power, and so on). Once set, the amount of flash illumination won’t change unless the shooter changes it him- or herself. Flash exposure doesn’t change from one shot to the next (as long as flash-to-subject distance stays constant).

With manual flash, even if the subject changes — such as a shot of a bride in a white wedding dress one moment, and a shot of the groom in a black tux a moment later — flash exposure doesn’t need to change, as long as the flash-to-subject distance stays the same. When a series of shots are going to be taken of a subject or scene, and the flash-to-subject distance isn’t expected to change, manual flash exposure can be a welcome feature for the critical photographer. And, of course, Canon EX-series speedlites have offered manual flash power since the launch of the E-TTL flash system back in 1998.

What is Metered Manual Flash Exposure?

Simply stated, any EOS-1D or EOS-1Ds camera, including the latest EOS-1D X, can take a spot reading of a pre-flash, lock that reading into memory, and display a separate reading in the viewfinder that shows how that level of manual flash exposure will be rendered for that subject. Then, adjust the lens aperture, ISO, and/or manual flash power level until the viewfinder read-out is where you want it to be. No separate, hand-held flash meter is needed, and a series of test exposures usually isn’t, either. Here’s what the photographer needs to do:

  • Set your EX-series speedlite into Manual flash mode, and select an appropriate manual flash power level on the speedlite
  • Pre-set an appropriate ISO on the camera, for the type of shooting conditions, flash-to-subject distance, and so on
  • Pre-set an appropriate ISO on the camera, for the type of shooting conditions, flash-to-subject distance, and so on
  • Look through the viewfinder; focus on your subject (use any AF point you want).
  • Center the viewfinder over the part of the subject or scene you want to measure flash exposure from, and press the camera’s M.Fn or FEL button (the small button immediately above the shutter button on EOS-1D and EOS-1Ds cameras). A single pre-flash will fire.

An important note: even though this Metered Manual Flash Exposure system takes a spot meter reading of a single pre-flash, you do not have to switch the camera’s metering system to Spot metering mode. All we’re speaking of here can be achieved with the camera’s metering system set for any of the available metering patterns (Evaluative metering, etc.).

You will instantly see a new analog exposure scale appear running vertically on the far right of the viewfinder display, as soon as the pre-flash fires. This is in addition to the normal analog scale, just to the left of this new one, which displays ambient exposure level.

All the metering marks, except one, become highlighted on this new scale — the “empty” index mark indicates the flash exposure level.

A look at possible viewfinder displays

Ambient manual exposure indicator only.

This is what you might see immediately before pressing the camera’s M.Fn or FEL button. In this hypothetical case, camera is in manual exposure mode. If shooting indoors or in low light, and pre-set to a combination of relatively fast shutter speed, moderate aperture, and low ISO, the metering indicator indicates ambient light will be under-exposed — and the downward arrow tells us by more than 3 stops. A camera set to 1/250th second, f/8, and ISO 100 would likely register this in a typical indoor setting.
Pre-flash fired – proper exposure level.

When M.Fn or FEL button is pressed, a single pre-flash is fired, and a spot meter reading is taken from the center of the viewfinder area. If the combination of lens aperture, ISO, manual flash power level, flash-to-subject distance, and subject reflection all combined to indicate a “proper” exposure, this is what you’d see — a new exposure scale instantly appears, with a single blank spot indicating the metered manual flash level. Most of the time, it won’t be perfect when you first press the button!
Pre-flash fired – current flash exposure level 2 stops under-exposed.

If you’re too far back, your flash manual power level is too low, your initial lens aperture is stopped-down too far, or your ISO is too low (or, if you’ve spot-metered off a dark-colored subject), you might see something like this – the far-right side metering scale tells you that at this moment, the camera reads flash at the center spot as being two stops below a normal, middle-gray exposure level. The downward-pointing arrow just to the left is the ambient exposure level, and is always read separately. In this case, as mentioned above, hypothetical camera settings result in ambient exposure being far under-exposed – in a typical indoor picture, this may not be a problem.
Pre-flash fired – current flash exposure level more than 3 stops under-exposed.

Maybe you left your flash’s manual power level at 1/64th power, your lens at f22, and you’re 20 feet from your subject. One way or another, the single downward-pointing arrow on the far right side indicates flash exposure, right now, is more than 3 stops under-exposed. A similar far-right arrow pointing upward would indicate severe over-exposure at the spot metering area. Either way, you’ve got some adjusting to do — but it’s easy, and the EOS-1D or 1Ds series cameras will continually update the exposure scale to show you how current settings relate to your last spot meter reading.
Adjusting manual flash exposure, after the spot meter reading is taken

Pressing the M.Fn or FEL button fires a single pre-flash, and you get a viewfinder read-out of how the camera reads flash exposure from the center spot area at the current flash/camera settings in place. If the flash exposure scale is perfectly centered, you may be ready to shoot. But what if it’s not (and it usually won’t be)? You can adjust any of the following settings to make things right.

And the key is that as you do, the viewfinder exposure level scale updates continually, so you can see the effect of your changes, and know when manual flash exposure is likely to be just right.

  • Lens aperture:
    This may be the first control many users will reach for. With an EOS-1D or EOS-1Ds camera in Manual exposure mode, simply turning the large Quick Control Dial on the back of the camera will change the lens aperture, and as you change it, you’ll see the flash exposure scale in the viewfinder move. Turn the dial until the flash exposure scale is centered, or deliberately off-center to account for light- or dark-colored subjects. Of course, the actual f-number will appear in the viewfinder, below the image area, so you’re always aware of what f-stop you’re setting.
  • ISO:
    If you need to maintain a specific lens aperture (for depth-of-field purposes, or any other reason), changing ISO with manual flash will alter the flash’s effective exposure level. Increasing ISO will simultaneously increase flash exposure level, if all other variables stay the same. And vice-versa, of course. If you do press the ISO button and change the camera’s flash exposure level, however, you will lose your flash read-out in the viewfinder, and will have to take another pre-flash reading by placing the center spot area in the finder over your subject, and pressing the M.Fn or FEL button on the camera again.
  • Flash power level: Manual flash with a speedlite can be fired at full (1/1) power, or at fractional power levels — 1/2 power, 1/4 power, and so on. High-end speedlites like the 580EX II and 600EX-RT can be set as low as 1/128th of full power, for situations where only a tiny bit of flash is needed. Regardless, if you fire the pre-flash, and the exposure scale in the finder indicates over- or under-exposure, you can change the flash power level to get to where you need to be. If you use the speedlite’s controls, on flashes like the two mentioned above, you can see the change on the flash exposure scale in the viewfinder as you make adjustments on the flash itself. If you use the camera’s External Speedlite Control menu to change manual power level, you’ll need to take a new spot reading to get an updated read-out in the viewfinder.

Once you get the flash exposure scale to indicate proper exposure, you should be ready to shoot. And the cool thing is, since it’s manual flash exposure, flash exposure on the subject won’t change as you shoot multiple pictures of the same scene or subject. Whether you take one shot, a dozen, or a hundred, as long as your flash-to-camera subject distance stays constant, your exposures will as well — even in the face of wardrobe changes, subject changes, lens changes, and so on.

Light and dark colored subjects

The spot meter reading of flash you’re taking is a reflected-light reading, reading light reflected from the subject back into the camera. Accordingly, it’s going to be influenced by whether the part of the scene you’re reading is light-colored, dark-colored, or effectively a middle tone.

If you simply “center” the flash exposure scale after taking a spot reading of manual flash exposure from a white subject, the system will have given you information that will render it close to a middle shade of gray. In other words, a dark, under-exposed final shot of that white subject. And if it was a dark-colored subject, and you spot-metered off of that and centered the flash exposure scale, it’ll likely result in a vastly over-exposed flash image.

The bottom line is simple: Deliberately over- or under-expose on the flash exposure scale, when you know you’re reading a lighter- or darker-than-mid-tone subject.

Spot meter reading off of light-complexioned face

You may want to deliberately over-expose such a scene by 2/3 to one full stop, as indicated here. Take one Metered Manual Flash Exposure reading, deliberately over-expose a bit (by opening-up the lens aperture, raising ISO, or increasing manual flash power level), and now leave it — even if the subject changes, as long as your distance stays the same, manual flash exposure will remain the same, too.
Spot meter reading off a near-white object

You’ll likely get proper manual flash exposure by setting the viewfinder’s flash scale so it shows even more intentional over-exposure — here, 1 and 2/3 stops (1.7 stops) over exposed. Adjust the lens aperture, ISO, or flash power as needed to move the flash scale to where you think it should be. Once you get a good exposure, if your distance from flash to subject doesn’t change, you don’t need to change exposure, either!
Spot meter reading off a dark object

Taking a spot reading off a black tux at a wedding might result in gross over-exposure. Adjusting aperture, ISO and/or flash power until the viewfinder scale shows intentional under-exposure (here, two stops under is indicated) will usually get you the results you need. The key, again, is that you see this in the viewfinder — and can set, change, or re-set manual flash power quickly and easily, without leaving the camera position.
Blending manual flash and ambient light

The examples we’ve mentioned up to now assume that we’re shooting manual flash indoors, and that ambient light in the scene won’t be a factor (it’ll be greatly under-exposed by “normal” camera settings for flash). But whether you’re indoors, or outdoors in bright daylight, you’re completely free to adjust your camera settings so that ambient light is close to proper exposure, or right-on. Ambient exposure is handled separately; the easiest way to adjust it without impacting manual flash is to change shutter speeds. Changing ISOs or lens apertures, with manual flash, will require updating the flash settings (easy to do with Metered Manual Flash Exposure… just take a new spot meter reading of flash after changing ISO and/or aperture, and tweak as necessary to get the viewfinder scale to show the flash exposure level you want).

Here’s what you might see in the viewfinder if you adjusted ambient exposure to keep it slightly subdued (2/3 of a stop under, in this example), and adjusted flash exposure so that the camera reads it as right-on.

You’ll always see separate read-outs for ambient and flash exposure on the twin analog scales in the viewfinders of EOS-1D and EOS-1Ds cameras, when using Metered Manual Flash Exposure.

One important note about ambient metering with flash: with the sole exception of the EOS-1D X, all other versions of EOS-1D or EOS-1Ds cameras will always take an overall, averaged meter reading of ambient light whenever a Canon EX-series speedlite is connected, turned on, and in a recycled state (ready-indicator appears in the viewfinder). In other words, even if you’ve set your camera to take spot readings of ambient light by changing its metering pattern, as soon as a speedlite has recycled, it over-rides your choice of metering pattern. With all models except the EOS-1D X, to get your choice of metering pattern for taking ambient light readings, you need to momentarily turn your speedlite off. Take your readings, set the camera manually, and then turn the flash back on. None of this affects the Metered Manual Flash Exposure system we’ve been discussing. Regardless of what meter pattern is currently selected on the camera body, it will use Spot metering for measuring flash, whenever you fire the pre-flash via the FEL or M.Fn button with any of these cameras.

Metered Manual Flash Exposure and Canon’s wireless speedlite system

Everything we’ve mentioned about metering manual flash exposure in-camera, using any version of the EOS-1D or EOS-1Ds cameras, can be achieved with manual flash power and Canon’s wireless E-TTL. This applies to both Canon’s traditional “optical” type of wireless flash, as well as the new radio-based wireless flash introduced with the Speedlite 600EX-RT.

Many Canon owners aren’t aware that the Canon EOS wireless “E-TTL” system can be used with fully manual flash, too. Multiple speedlites can be fired so that all fire at the same manual power level (such as full 1/1 power, 1/2 power, and so on), or ratios can be set-up (A:B or A:B:C), with each group firing at different, user-selected power levels. And, if you’re using a Canon 500- or 600-series speedlite on-camera as a “master” unit to trigger your slave units, you can set each group’s power level on the “master” unit — no need to change settings on each individual slave unit, or even re-set the MODE setting on the off-camera flashes — just set the “master unit” to Manual flash mode, and proceed from there. (In other words, when you start, “slave units” will read “E-TTL” on their LCD panels — this is OK!) Manual flash mode, and the manual power level, are communicated to the off-camera flashes when you take a pre-flash reading, or when you shoot the final picture(s).

And, the new radio-based wireless system with the Speedlite 600EX-RT and optional Speedlite Transmitter ST-E3-RT make this possible with up to 15 “slave units” over a distance range of up to 98 feet from the camera.

The point here is that even if you want to use a complex, multi-flash lighting set-up with Canon’s wireless flash and manual flash exposure, you can use the exact same Metered Manual Flash Exposure system to spot-meter your flash in-camera. Just pre-set what you think will be appropriate lens aperture, ISO, and flash power settings, and press the M.Fn (or FEL) button on the camera, to take a pre-flash reading from the multiple speedlites. Again, it’s always a spot meter reading, regardless of where the camera’s metering system is set (Evaluative, Center-weighted, etc.).

Intentional adjustments to move the flash exposure scale in the viewfinder away from its “zero” or centered position will still be needed if your spot reading of the pre-flash is taken from unusually light or dark-colored objects.

Wireless manual flash with the ST-E2 transmitter:

Finally, if you trigger your off-camera “slave units” with the optional Canon Speedlite Transmitter ST-E2 (note — this doesn't apply to the ST-E3-RT unit), you’ll see that the ST-E2 doesn’t have a control to change flash exposure mode on the slave units. With the ST-E2 as the triggering device, you’ll need to separately put each “slave unit” into its stand-alone manual exposure mode. Press the slave unit’s MODE button and hold it in continuously for two to three full seconds, until the “E-TTL” indication on its LCD panel changes to a blinking “M”. Now, adjust its power, using commands on the speedlite (full 1/1 power, 1/2 power, and so on). Each slave unit must be adjusted individually, for manual flash exposure control via the ST-E2 transmitter.

Compatible Canon EOS equipment for Metered Manual Flash Exposure

Simple: Any Canon EX-series speedlite, including Canon’s Macro Ring Lite MR-14EX, and Macro Twin Lite MT-24EX. And, any of the following top-of-the-line Canon EOS cameras:

  • Canon EOS-1D X
  • Canon EOS-1D Mark IV
  • Canon EOS-1D Mark III
  • Canon EOS-1D Mark II N
  • Canon EOS-1D Mark II
  • Canon EOS-1D
  • Canon EOS-1Ds Mark III
  • Canon EOS-1Ds Mark II
  • Canon EOS-1Ds

Unfortunately, this admittedly very cool feature is not available on less-expensive EOS models, and there’s no way to update them for compatibility with the Metered Manual Flash Exposure system.

Some additional hints

A few tips you may want to keep in mind when shooting with manual flash, and measuring it with the in-camera Metered Manual Flash Exposure system in EOS-1D and EOS-1Ds series cameras:

  • Consider starting with your manual flash power set around 1/8th power
    This gives you wiggle-room to raise or lower flash power, if your first pre-flash reading shows you need more or less flash upon your scene. If you start at full 1/1 power, you’ll frequently be having to re-set it and lower it, sometimes significantly if you’re relatively close to a subject.
  • Remember… with manual flash, you can’t simply change distances from flash to subject, as you can with E-TTL automatic flash (that is, unless you adjust exposure when you do)
  • Like any form of manual exposure control, consider the spot readings of flash to be a starting point… fine adjustments can always be made to get exposure more exact
  • Again, Metered Manual Flash Exposure readings are always spot readings, using roughly 2.5 to 3% of the picture area, from the dead-center of the focus screen — regardless of what AF point(s) you’re using. If you apply the Custom Function in your EOS-1D or EOS-1Ds to link Spot metering to an active AF point, these manual flash exposure readings will be taken from this new, off-center spot area.
  • Remember… with manual flash, you can’t simply change distances from flash to subject, as you can with E-TTL automatic flash (that is, unless you adjust exposure when you do)
  • Keeping the Metered Manual Flash Exposure reading visible in the viewfinder: By default, any time you press the FEL/M.Fn button, spot readings taken from it stay active for 16 seconds. This is often sufficient time to make the adjustments you need. But the length of time it stays active before a shot is taken, and the length of time it continues to appear after a shot is taken, can be changed using the Timer adjustments within the camera’s Custom Functions:
    • 16 second timer — change the length of time the initial read-out in the finder stays visible after the M.Fn or FEL button is pressed, from 1 second to one hour. Initial factory-default setting is that it stays active for 16 seconds after the pre-flash fires.
    • 2 second timer — change how long the finder display continues to appear after a shot is taken. Normal factory default is 2 seconds; EOS-1D and EOS-1Ds models allow changing this over a range of 1 second to 1 hour.
    • 6 second timer — this one influences how long the meter and its viewfinder display stay active if you don’t take a shot. Since the 16-second timer supersedes this one during Metered Manual Flash Exposure (when the M.Fn or FEL button is pressed), this won’t directly affect the finder display for this feature.

Far too many experienced shooters miss out on great features in today’s cameras, feeling if they do things the traditional way, they’ll have more control and get better results. If you prefer using manual flash instead of automatic E-TTL, that’s great — it’s simply another way to get the pictures you need. But using one or more Canon EX-series speedlites with the Metered Manual Flash Exposure mode combines the control of manual flash exposure with super-quick in-camera metering. And, this is done with very precise spot measurements off of your subject, allowing critical users to very carefully measure and control how that manual flash exposure will be applied.

If you own an EOS-1D or EOS-1Ds camera, and haven’t tried this feature, give it a whirl. It makes portable and compact EOS speedlites all the more practical for critical shooters, and empowers the photographer to exercise all the control over flash exposure he or she could want.

The CDLC contributors are compensated spokespersons and actual users of the Canon products that they promote.

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