Digital Photography For What It's Worth: User-to-user help for digital photographers in general and Oly Camedia users in particular. Click to go to home page.

Digital Photography For What It's Worth

Fern emerging from frozen lava whirlpool, Napau Crater Trail, Hawaii Volcanoes Nat'l Park. Click to see 1280x960 original. [D-340L]

Marks content from authoritative sources or confirmed by my own personal experience External flash with Oly C-series digitalsvaried implementations of a valuable tool

On this page—

See also the External Flash Checklist

Last updated July 27, 2004

Why Bother with External Flash?

Film and digital cameras are more alike than they are different, and their internal flash (IF) units are cases in point. IFs are inescapably limited by size, flash-lens distance, power consumption and aiming constraints. They work fairly well for fill flash, and pop-up IFs often outperform their fixed counterparts, but even pop-up IFs are no match for external flash (EF) units when it comes to power and finesse. EF is also the weapon of choice in close-up work and in the never-ending battle against red-eye.  

Compared with internal flash, an EF unit will typically 

  • Offer multiple power settings, most if not all well beyond the reach of the IF.

  • Permit much greater camera-subject distances in under-lighted scenes.

  • Provide much more even lighting with fewer unwanted shadows via bounce flash techniques.

  • Largely eliminate red-eye.

  • Improve close-up flash work by allowing flexible aiming and positioning of the flash unit, including bounce techniques.

  • Eliminate shadows cast by mounted filters, lenses and lens tubes

The downsides of EF?

  • Extra gear: You'll end up with a lot more stuff to buy, carry, futz with, maintain, protect, and you'll need more batteries, too. The added expense can be substantial, especially if you go for a dedicated TTL flash setup.

  • Extra steps: You'll have to plan ahead and work with camera menus to make the most of EF.

  • Limited subject tolerance: My entire family run screaming when they see me coming with my eyebrow-singeing 110' GN EF unit attached to the camera.

In most instances, I find that EF pros greatly outweigh the cons. I rely on my IF only in a pinch.

External Flash Terminology

To simplify the discussion below, I've adopted the following shorthand notation:


External flash used in conjunction with internal flash


External flash used alone, with the internal flash disabled

The EF-IF approach generally results in better lighting, but EF+IF also has its uses. 

In the EF context, TTL means precision EF control by the camera's through-the-lens (TTL) metering system. EF units supporting TTL control by a specific camera are said to be dedicated, and they tend to be expensive. You may be able to use dedicated EF units with other cameras, but not to their full potential.

The maximum range an EF unit can deliver is usually reported as a guide number (GN) at a specified ISO setting, as detailed below. Suffice it to say here that GN divided by the camera-subject distance (including any bounces) gives the f-number of the recommended aperture. Thus, you'd use an f/5.6 aperture with a EF unit rated at GN 110' and a subject 20' away (110'/20' = 5.5). 

The simplest EF units are on-off affairs, but adjustable non-dedicated EF units tend to have both manual and automatic power settings. The manual setting forces maximum flash power, regardless of ambient light levels. The automatic settings work in concert with a light meter built into the flash to limit EF output. Since shutter speeds are generally orders of magnitude longer than flash durations, they remain relevant in EF work only to the extent that ambient light competes with flash. Manual and automatic EF settings are therefore meant to be used with specific apertures. Most automatic EF units come with aperture tables printed on the back.

For more flexible lighting control, better EF units come with heads that tilt, zoom and swivel—something no straight-ahead IF unit can offer. Tilt controls up-down flash aim independent of camera aim, while swivel controls right-left flash aim. Zoom controls flash beam width and, indirectly, beam intensity. (The wider the beam, the less intense at the subject for a given flash lamp output.) Such flexibilities are especially important in bounce flash techniques.

Many EF units come with simple PC cord sync sockets. PC in this context refers to a specific 2-lead connector type and has nothing to do with computers.

See for Yourself

To see how EF can extend your photographic reach and improve your flash lighting, visit Todd Walker's thorough and nicely illustrated external flash test pages.

What You'll Need for External Flash

See also the External Flash Checklist

To use EF with a digital camera, you'll need at minimum

  • An external flash unit with a suitable sync socket or hotshoe and a safe trigger voltage (slave sync is optional and generally not recommended)

  • A suitable sync cable or PC cord (or a PC-to-hotshoe adapter if your flash has only a hotshoe)

  • A suitable camera bracket to mount the flash (many digitals lack built-in flash mounts), 

  • One or more bounce cards, and

  • If you have a C-2000Z, a little patience to sort through the rather cryptic C-2000Z EF implementation to find what works best for you.

The patience may be hard to come by, but check your film camera bag for the other items before rushing out to buy something new.

A Warning About EF Trigger Voltages

Marks the paydirt Before hooking your expensive digital camera up to an EF unit you've used with a film camera, confirm that its trigger voltage is safe for your expensive digital camera.

Kevin Björke's superb Canon G1 external flash page will show you how to measure its trigger voltage and how to deal with trigger voltages that turn out to be uncomfortably high.

Some older external flash units develop surprisingly high trigger voltages across their main hot shoe or sync socket terminals—sometimes well in excess of 200V! That voltage will be applied directly to your camera's flash synchronization socket. An occasional shot at high trigger voltage probably won't damage your camera's sync circuitry, but routine use will eventually do harm.

How High Is Too High?

The maximum safe trigger voltage for Oly digitals remains controversial, but 6V is safe for most if not all modern cameras, digital or otherwise. Unfortunately, the C-2000Z and C-2020Z manuals are mute on this front, and RPD posts have yet to point in a consistent direction. The Oly C-5050Z is said to have a protective mechanism that shields its flash sync circuit from high sync voltages, but I can't confirm that. Wein makes a protective SafeSync relay, but it's seen mixed compatibility reports on RPD.

My C-2020Z seems to have survived a few sessions with the tiny ancient PROMASTER FM600 EF I rediscovered in a stash of old camera gear, but this PROMASTER went back in the closet when I measured a whopping 253V trigger voltage at full charge.

Slave Workaround?

To get around an uncomfortably high trigger voltage in an otherwise desirable EF unit, you might consider a small external slave trigger like the Wein peanut. These devices plug into the PC socket on your EF unit and trigger it when they see the light of another flash. 

Of course, this less-than-ideal solution dooms you to EF+IF lighting. Worse yet, these film-oriented units probably sync on the first flash they see and are thus unlikely to be compatible with the majority of digital cameras emitting a pre-flash.  

Bounce Flash to the Rescue

Aim your flash (internal or external) directly at a subject, and you'll maximize harsh shadows, red-eye and the "spot-light effect" right along with the illumination. For animate subjects, you'll also likely come away with that ever-flattering "deer in the headlights" look. But bouncing the flash beam off a judiciously chosen surface like a nearby white wall almost always provides more favorable lighting with fewer unwanted shadows and vastly reduced red-eye.

Bounce Issues

Effective diffusion of the flash beam and optimum lighting angle(s) give bounce flash its punch. To get the most from your bounces, you'll have to balance

  • the angles involved—is your subject shown in a better light?

  • the total flash path length—is your EF really up to it?

  • the color and texture of available bounce surfaces—are they helping or hurting?

Marks the gotchas Successful bounce flash technique requires careful attention to all these details. 

With a digital camera, you're free to experiment at the scene as long as your subject stays put.


Since side-lighting is generally best for human (and most other) subjects, bounce off walls and other vertical surfaces rather than horizontal ones like ceilings. Avoid the floor at all costs. (Remember how you look with a flashlight under your chin?)

If a ceiling's your only option, be sure to add a bounce card to get some direct but well-diffused flash onto the subject to soften the top-lit shadows.

Follow an estimated trajectory of your flash beam with your eye to help you imagine how it will fall on your subject. Think billiards.

Path Length

Bouncing your flash may work wonders, but it won't magically increase the effective range of your EF unit. One bounce off a 20-foot ceiling can easily dilute most EF beams into oblivion. Again, follow an estimated trajectory of the flash beam with your eye and estimate the total path length the flash beam must travel to reach your subject. 

Ideally, flash intensity will fall off with distance at the same rate whether the path to the subject is direct or folded by perfect reflections, but diffusion losses from imperfect reflecting surfaces will take a noticeable toll. 

Follow your EF unit's guide number (GN) here. If your GN divided by the total path length is less than the f-number of any aperture you're able or willing to apply, then your bounce path is too long. And don't forget to take ISO and diffusion losses into account.


The bounced flash arriving at your subject will pick up the colors of the reflecting surfaces. For better or for worse, your subject will them pick up as well. 

Marks the paydirt White bounce surfaces are safest. If white isn't an option, warmer colors are generally safer than colder ones. 

Blue and green bounce surfaces won't be very flattering to human subjects but may be just the ticket for in-law and blackmail shots.


Effective bounce technique relies on diffusion of the flash beam to reduce harsh shadows and the spotlight effect. Smooth bounce surfaces generating mirror-like (specular) reflections won't do you much good. Overly rough surfaces can waste a lot of light. Aim for something in between.

To get an idea of what bounce flash can do for you, see Todd Walker's external flash test pages.

Bounce Cards

When you run seriously afoul of any of the bounce issues enumerated above, it's time to get out a bounce card—a 6" long piece of heavy white low-gloss card stock cut to the width of your flash. Use a rubber band to hold the bounce card to the backside of your EF unit's bounce head with a visor-like overhang of 3" or so. With the bounce head angled just off the vertical at 75° or so, the bounce card will add a softly diffused, forward-directed flash that nicely fills in shadows without blowing out your subject. 

To allow part of the flash beam to bounce off a wall or ceiling, cut another card to 50-60% of the width of your flash head and carry that one, too.

Marks the paydirt A bounce card is far and away the single most effective (and inexpensive) addition you can make to your EF bag of tricks. 

Bounce cards are almost always beneficial, but they're especially helpful when no other suitable bounce surfaces are available—e.g., when the nearest ceilings or walls are too far away, or have an untoward color, texture, shape or orientation.

To see what bounce cards look like in action and what they can do for your flash work, I once again strongly recommend Todd Walker's external flash test pages, particularly the later version.

Bye-bye Red-eye!

When it comes to red-eye, an ounce of prevention is truly worth a pound of cure—as elaborated in a separate dpFWIW red-eye article—and nothing combats red-eye like a bounced and well-positioned EF unit. With a compact camera like the Oly rangefinders, external flash is the single most powerful weapon in the fight against red-eye. 

EF-IF Red-eye Countermeasures

Marks the paydirt To subdue red-eye before the fact,

  • Ditch the internal flash and use EF instead. 

  • Arrange to shoot your subjects in brighter ambient light if you can.

  • Capture your subjects while they're still sober. Anything that further dilates their pupils is the enemy.

  • Have your subjects look away from the lens.

  • Bounce your EF, preferably off a nearby white ceiling or wall. (If the total path length threatens to sap its effectiveness, consider attaching a bounce card.)

  • Get closer, or find some other way to keep your EF at least 5° away from your camera lens as seen by the subject.

Use these counter-measures in combination if possible. 

The last item above deserves a little explanation. The cone of reflected flash emerging from the pupils of a flash subject has a half-angle of ~ 5°.  Luckily for us photographers, the tangent of 5° is very close to 1/12, so 6 feet of camera-subject distance translates into 6 inches of lens-flash distance required to insure that the retinal reflection misses the camera lens. Same with 10 feet, 10 inches, and so on. To go out to 10°, it's still a good approximation to double the camera-subject distance in feet to get lens-flash distance in inches.

With a suitable camera bracket—needed for EF with most Oly digitals in any event—you can easily mount your EF far enough away from the lens to eliminate red-eye entirely at short to medium camera-subject distances, even without the bounce. My bracket allows a maximum lens-flash separation of 9 inches, which subtends a 5° angle at a subject 9 feet away and a 10° angle at a subject 4.5 feet away. 

The greater lens-flash separation achieved by the C-2100UZ's pop-up IF design should reduce red-eye substantially, and an early review suggests that it does.

EF-IF Exposure and White Balance Considerations

Oly digitals coordinate exposure and white balance well with their internal flash, but they know not a whit about generic EF units. In generic EF-IF work, one must deal with exposure and white balance head-on.

The exposure and white balance tips below apply only to EF-IF shooting with an Oly digital and a generic EF unit. Throwing the IF back into the mix would certainly change things, but precisely how I'm not sure. How Oly digitals with the TTL sync socket would handle such things when coupled with a supported TTL flash, I have no clue.

Figuring Manual Flash Exposures

Be prepared to calculate flash exposures on your own in the following situations:

  • Your EF is a manual unit with no automatic control of flash duration.

  • You elect to set your automatic EF on manual to get maximum power.

  • You're doing close-up work, where automatic EF settings are likely to fail.

Guide Numbers

Fortunately, it's easy if you know the guide number (GN) for your EF at one or more ISO settings. The GN is a measure of the intensity of your EF beam. For proper EF-IF exposures when camera-subject and camera-flash distances are about the same, use this formula to set your aperture:

  • Aperture f-number ~ (GN at actual ISO) / (distance to subject in ft)

If your flash documentation gives only a single GN, say at ISO 100, use this version:

  • Aperture f-number ~ (GN @ ISO 100) * fudge / (distance to subject in ft)


  • fudge = sqrt(2) ^ [(actual ISO / 100) - 1]

In other words, stop down one full stop for each doubling of ISO over the ISO tied to the GN you're using.

Guide Number Example

Consider, for example, my external flash, which claims a GN of 110' at ISO 100. For a subject at 20 ft and the camera at ISO 100, you'd choose an f/5.6 aperture because 110/20 = 5.5. Bumping the ISO to 200 would require you to stop down to f/8 instead. Further bumping the ISO to 400 would require an aperture of f/11.

Keep in mind that in manual, aperture-priority and shutter-priority modes, the C-20x0Z always uses the ISO you've set, but

Marks the gotchas In program (automatic exposure) mode on the C-2000Z or with ISO set to auto on the C-2020Z, the ISO the camera selects may not match that tied to the EF guide number used in the exposure calculations above.

EF-IF White Balance

Here's another small catch to the EF-IF approach: Turning off the onboard flash blinds the automatic white balance (WB) feature on the most digital cameras by eliminating the brief pre-flash used to scope out the scene. Overly blue EF-IF images may result. The auto-WB problem goes away with IF enabled, EF+IF shots included, but there's a simple EF-IF solution:

Marks the paydirt Use manual white balance for EF-IF shots, at least for the important ones.

The sunny daylight manual WB preset is probably the safest choice for EF-IF situations, but you may prefer the bluer overcast setting.

Whatever you do, 

Marks the gotchas Don't fall into the trap of choosing the tungsten WB setting just because the ambient light happens to be incandescent.

In all likelihood, your bluish flash will overpower the indoor lighting and your EF-IF images will come out doubly blue! 

Truth be told, the risk seems to be small in practice. Most of the time, I've managed to get by with auto-WB in my C-2020Z EF-IF shots. Failing that, I can usually fall back on post-processing to correct white balance issues.

When in doubt, check your work at the scene via the LCD.

Identifying "Important Shots" Ahead of Time

Let's pause for a moment to examine this tempting idea of picking "important" shots in advance, starting with

Gumperson's Law: The least likely contingency will always occur at the most inopportune time.

Superficially, the law simply reinforces what common sense demands: Take the greatest care with the shots known to count the most.

Unfortunately, trying to pick all the important shots in advance runs you smack into the less well-known but equally inescapable

Gumperson Recursion Theorem: Any scheme devised to avoid constant vigilance through the application of Gumperson's Law is itself subject to Gumperson's Law. 

In other words, a certain number of shots you'll later recognize as immensely important will inevitably sneak by while your guard's down. That's why it's safest (but usually too costly) to follow the 

Mr. Rogers school of photography: "All shots are special, aren't they, Melissa? I think so. How would you like to visit the pencil factory with me today?" 

Incidentally, the Gumperson recursion theorem forms the basis of the controversial Copenhagen derivation of Murphy's Law.

Marks opportunities to bypass long-winded discussions and cut to the action line. Click to review Limited Warranty section on the home page. This concludes the generic portion of this article. If you're not an Oly user, the jump icon at left will take you back to the dpFWIW article index, but a good bit of the material in the next section will translate to other cameras.  

EF Sync Options for Popular Oly Digitals

Marks the paydirt There are 2 basic ways to sync an EF unit to any digital camera:

  • Connect it to the camera's flash synchronization socket (AKA PC connector, sync socket, TTL socket, etc.)

  • Use a slave flash designed to trigger off the light of the camera's internal flash.

EF-IF flash work requires the former method; the latter forces an EF+IF approach. The subsections below flesh out sync details for Oly digital rangefinders and the C-2100UZ by way of illustration. Other digital cameras are likely to offer similar sync options.

Using Oly's Proprietary TTL Sync Socket

After the C-2020Z, Oly dropped the standard PC cord EF sync socket in favor of a proprietary 5-pin TTL sync socket designed to drive its very sophisticated but pricey FL-40 TTL external flash unit. Oly also offers its own FL-BK01 flash bracket with a hotshoe that supports the FL-40 and compatible TTL units via a required Oly FL-CB01 TTL-to-TTL cable. A screw-on cap covers the TTL sync socket.

The new Oly TTL sync socket also supports generic EF units with PC cord sockets via Oly's overpriced but inescapable FL-CB04 TTL-to-PC adapter cable

Oly FL-40 EF Unit

Oly's powerful GN 130' FL-40 is by all accounts a worthy flash and works beautifully with supporting Oly digitals, but it still costs well over $350. At that price, you'd think the FL-40 package would include the inevitable Oly FL-CB01 TTL-to-TTL cable (~$40), but that doesn't appear to be the case; nor does it include Oly's FL-BK01 flash bracket (~$60). 

Note: All prices quoted above are mail order as of 4Q2002. 

To see an older C-3030Z handsomely decked out with an Oly FL-40 flash, FL-BK01 flash bracket and FL-CB01 TTL-to-TTL cable, and to learn more about the FL-40 itself, scroll about halfway down through this C-30x0Z review at To see the C-2100UZ with the same EF setup, see their C-2100UZ review.

TTL Alternatives

Fortunately, Metz and PROMASTER now sell richly-featured dedicated TTL electronic flash units able to make full use of the Oly TTL sync socket at $100-150 under the going FL-40 price, and SunPak is said to have one slated for a 2003 release. The PROMASTER and Metz dedicated EF units also require "optional" adapter cables, in some cases from their own catalogs and in other cases from Oly. I've seen positive reports from 2 satisfied Oly/PROMASTER 5550DX users but have no user-to-user info on the Metz offerings at this juncture.

For more detailed information, visit Mike Meissner's in-depth Oly TTL flash article. One thing's very clear: By the time you tally up the wherewithal, you'll spend big money for a dedicated TTL flash solution, no matter who supplies it.

Oly TTL Adapters

To use the Oly TTL sync socket with flash units lacking dedicated support for it, you'll need at the very least the Oly FL-CB04 TTL-to-PC adapter cable. If your camera lacks a hotshoe, you'll also need a suitable flash bracket. Whether the TTL-to-PC cable ultimately connects to the bracket's hotshoe or to the EF unit itself will depend on the equipment involved. Unfortunately, the TTL-to-PC cable has a reputation for fitting loosely at its PC cord end, at least with some EF units.

Below is a direct quote from Oly tech support ca. August, 2000, when the EF accessories listed below first hit the street. As of 4Q2002, everything there still applies to the C-3030Z and to all subsequent Oly digitals.

Thank you for contacting Olympus Digital Technical Support in the United States.

The following flash brackets and cables are available for use with the C-3000/3030 and the C-2500 for connecting various external flashes:

  • FL-BK01 Flash Bracket, Item # 200 666 ($59.95 street): This bracket consists of two connecting pieces; the base and grip. It can be set up for left or right handed use. A standard hotshoe flash or the FL-40 dedicated flash can be mounted on the bracket. The bracket uses a 5 pin TTL plug like that of the C-3000/3030Zoom; an appropriate cable (listed below) must be purchased separately to use this bracket.

  • FL-CB01 TTL-to-TTL Cable, Item # 200 664 ($39.95 street): 5 pin TTL connector on both ends. Use this cable to attach the C-3000/3030Zoom (and future cameras) to the FL-BK01 Flash Bracket.

  • FL-CB02 Hot Shoe-to-TTL Cable, Item # 200 663 ($59.95 street): Hot-shoe to TTL 5 pin connector. Use this cable to attach the C-2500L hotshoe connector to the FL-BK01 Flash Bracket.

  • FL-CB03 PC Sync-to-TTL Cable, Item # 200 662 ($39.95 street): PC Sync connector to TTL 5 pin connector. Use this cable to attach cameras with a standard PC Sync connector (such as the D-620L and C-2000/2020Zoom) to the FL-BK01 Flash Bracket.

  • FL-CB04 TTL-to-PC Sync Cable, Item # 200 661 ($39.95 street): TTL 5 pin connector to PC Sync Socket (female). Use this cable to attach the C-3000/3030Zoom to a standard PC Sync cable. External PC Sync flashes or studio strobes are examples of equipment that would be connected. This cable does not connect to the FL-BK01 Flash Bracket. Website has detailed information on our products...

Just add money.

NB: I'm not familiar enough with the C-7xxUZ series to say anything intelligent about it.

Using a Slave

Slave flashes—external units that fire when they see the light of another flash—require no physical connection to the camera, electrical or otherwise. With a slave, you can shoot in any exposure mode, not just the aperture-priority or manual mode the sync socket requires—provided you're willing to fire the internal flash. This exposure mode flexibility may come in handy when fast shutter speeds are in order.

Marks the gotchas Slave EF units will sync properly with an Oly digital internal flash only if set to trigger off the 2nd (main) flash.

Like the Olys, many digital cameras emit a brief pre-flash before opening the shutter for the exposure and firing the main flash burst. Unfortunately, slaves built for film cameras typically trigger off the first flash they see—in this case the pre-flash—and thus miss the boat entirely with most current digital cameras. 

Technical Note: The barely perceptible pre-flash at issue here differs from the better-known and clearly visible pre-flash of red-eye mode. It occurs with each firing of the IF and is apparently used to calculate IF power levels; it may also influence white balance calculations. According to testing by Mike Lynch, it doesn't seem to enter into exposure calculations, however.

Beware also of pure slaves offering no means for connection to the camera's sync socket: They'll be worthless when it comes time to disable the internal flash, and that's something you'll probably want to do more often than not with Oly digitals, as I've explained above

Digital camera slaves like those from SR Electronics are able to ignore the pre-flash and trigger off the main flash instead; they also support PC cable sync. Switch-hitters like their Digi-Slave Deluxe 3000 can be set to trigger off either the first or second flash to insure compatibility with any camera.

Using the Generic C-2000Z/C-2020Z Flash Synchronization Socket

The C-2020Z and its predecessor the C-2000Z both offer a generic PC cord sync socket. Neither offers TTL EF control. The C-2020Z's EF is much more user-friendly than the C-2000Z's. 

Marks the gotchas The C-2000Z's flash sync socket (PC connector) is active only in aperture-priority mode. On the C-2020Z, it fires only in aperture-priority and manual modes, and then only when enabled via menu.

The aperture-priority restriction usually makes perfect photographic sense—at least in low ambient light, where flash duration largely overrides shutter speed in determining overall exposure. Under such circumstances, aperture thus becomes your most direct and meaningful method of exposure control. However, if aperture-priority proves unsuitable in a particular situation, slave sync will allow you to shoot in any exposure mode your camera offers.

Cable sync always triggers when the main flash would have in EF-IF work. Cable sync thus circumvents the main-versus-pre-flash slave triggering issue complicating slave sync on many digital cameras. An old and very basic PROMASTER FM600 flash syncs perfectly with my C-2020Z via any PC cord. 

External flash units with a PC sync socket often come with the required sync cord. If your EF has only a hotshoe connection, you may need a suitable PC-to-hotshoe adapter in addition to or in lieu of a PC cable to mate it to the C-2020Z/C-2000Z. Your flash manufacturer may be able to supply you with the correct PC cable or hotshoe adapter or may point you to a 3rd party source.

If you use the C-2020Z/C-2000Z EF sync socket with any frequency, consider securing its tiny, unattached and easy-to-lose cap with a homemade tether.

Which Sync Option to Use?

In most situations, EF-IF setups produce better lighting than EF+IF configurations. If you have a C-2100UZ or a newer Oly digital rangefinder (C-3030Z or later), you'll get best EF-IF results with a dedicated TTL flash unit connected via the Oly FL-CB01 TTL-to-TTL sync cable, as detailed above. Excellent EF-IF results can also be had with the C-2020Z and C-2000Z using any decent EF unit with a PC sync cable connector and a safe trigger voltage.

Slave sync is completely optional, and for most Oly users, a waste of money. However, slave sync really shines when you need more than one flash—say, to control shadows in flower photography or studio work. In such cases, an EF+IF arrangement may be all you need—particularly if you can mount the EF unit on a tripod or other support some distance from the camera. A long sync cable will work, but slave sync will generally be simpler.

Another multiple flash scenario aided by slave sync comes up when high trigger voltages keep you from connecting some of the EF units involved in your lighting scheme to the sync socket. The unsafe EFs can be configured as slaves set to sync off the first (and only) flash of a safe EF connected to the sync socket in an EF-IF role. A similar setup can be used to trigger slaves hardwired to go off on the first flash they see. 

If you'd like to cover all your EF bets, look for a unit with a PC cable socket (or at least a hotshoe) and suitable slave triggering. A slave like SR Electronics' Digi-Slave Deluxe 3000 offers the flexibility needed to take maximum advantage of the all the EF options supported by the C-2000Z and C-2020Z but does not support Oly TTL sync.

A Flexible non-TTL EF Solution 

for the C-2020Z

The table below lists the issues generic EF hardware must address for the C-2020Z. The sweet but pricey proprietary TTL sync system used by Oly digitals following the C-2020Z is not addressed here.



Flexible EF sync—both slave and sync socket—to keep current and future options open* Slave designed for digital cameras with pre-flash
Indirect flash techniques Bounce-zoom head, for sure; a swivel head would be nice for vertical shots
Compatibility with non-digital cameras Switchable slave triggering on 1st or 2nd
No on-camera hotshoe Camera bracket with bottom-threaded tripod mount 
No unnecessary wear and tear on the camera's tripod thread Quick-release (QR) camera mount, with the plate henceforth living on the camera
* Table note: For most Olys, a non-slave flash with a sync socket would suffice in most situations.

The next table details the hardware solution I assembled to address the considerations above.





Digi-Slave Deluxe 3000  Slave flash with sync socket, 1st or 2nd flash slave triggering, manual (GN 110' @ ISO 100) and 2 automatic power settings, 0-90°/28-85 mm bounce-zoom head, 13.5" PC cord.  SR Electronics  $150
CB-2 Deluxe Camera Bracket Strong, well-balanced L-shaped aluminum camera bracket with a hotshoe mount, a 14"-20 bottom-threaded combined camera/tripod mounting knob, a comfortable molded grip and a safety strap. SR Electronics $35
Velbon QRA-635 magnesium alloy quick-release adapter Adjustable anti-swivel flanged plate with automatic safety latch, to protect the C-20x0Z's tripod thread. B&H Photo $40
Nexcell NiMH AA batteries 1350 mAh, set of 4. Thomas Distributing $8
Shipping and handling ~$20
Total (delivered) ~$233

*  Prices shown are from November, 1999.

Initial Impressions

These components work well together and with both the C-2020Z and the C-2000Z. In fact, they exceeded all my expectations. I haven't tested them with the C-2100UZ or later Oly rangefinders, but I have no reason to think they wouldn't work with Oly's FL-CB04 TTL-to-PC adapter cable.

The flash has performed well indoors with EF-IF technique. The DSD 3000 documentation is skimpy, but Larry Wilson of SR Electronics responded to my e-mail request for more information with a quick and thorough reply. Among other things, he suggested an aperture of f/11 for the manual power setting, f/8 for the higher automatic setting and f/4 for the lower automatic setting at ISO 100, at least for starters. I've also had success with an f/5.6 aperture at ISO 200 with the flash at its lower automatic setting. With a guide number of 110' @ ISO 100, the flash is quite powerful—in fact, at full throttle, my family complains loudly of its brightness.

The camera bracket has a very pleasing, well-balanced feel. With or without the flash, it substantially reduces camera shake, even at 1/30 sec and slower shutter speeds. And red-eye has become a rarity with this setup, thanks to the bounce and the 9 inch lens-flash separation the bracket affords. 

C-2020Z: Solid EF Support

See also the External Flash Checklist

Eager new C-2020Z owner Mike Wright wasted no time poring over the manual and testing all the new features after upgrading recently from his much-used C-2000Z. Since then, Ilkka Valkila kindly provided me with additional C-2020Z EF intelligence. Later, I purchased my own C-2020Z.

Among the many welcome improvements in the C-2020Z are these EF-related items:

  • The C-2020Z adds an explicit external flash menu item with Off/Auto/On options annotated with icons in both LCDs. The Auto setting triggers the external flash if and only if the camera deems flash necessary. The Off and On settings force the external flash off and on, respectively. Off is the default. Like the undocumented EF mode added to later versions of the C-2000Z to maintain workable EF-IF shutter speeds in aperture priority mode, this implementation sets a floor on aperture-priority shutter speeds in the 1/30 - 1/100 sec range whether or not there's an EF attached to the sync socket. (The C-2020Z and C-2000Z don't monitor the sync socket.)

  • The C-2020Z's new manual exposure mode allows users to do what flash photographers have always done with manual cameras—adjust aperture and shutter speed to get just the right blend of ambient light, flash, motion resistance and depth of field. It's common practice to set the shutter to 1/60 sec or so and use aperture to control final exposure, particularly when living subjects are present.

  • Dedicated buttons now control the all internal flash options but the slow-shutter flash sync settings, the only remaining C-2020Z menu functions pertaining to the internal flash. 

  • Added support for SHQ-JPEG recording in sequence mode extends sequence mode's potential utility in EF-IF work, however superfluous that may be given the C-2020Z EF support noted above. (SHQ-TIFF remains beyond sequence mode's reach, even in the mighty C-2020Z.)

C-2000Z: A Stealth EF Implementation

For most of late 1999, nary a week went by on RPD without a round of posts bemoaning the C-2000Z's well-hidden external flash (EF) implementation, particularly from users wishing to apply it in a studio setting.

Fortunately for later buyers, the beautifully executed C-2020Z update fixed the C-2000Z's catch-22 EF handling with both improved and more explicit EF sync logic and a fully manual exposure mode. If you have a C-2020Z, some of the C-2000Z workaround information given in this article won't apply, but much of the remaining EF information applies equally to both models. Look for the C-20x0Z designation in material that applies to both.

So What's The Problem with the C-2000Z? 

On the face of it, the camera's EF logic would seem to limit you to 3 dubious choices regarding use of the internal flash (IF):

  1. EF+IF: Let the IF shine and risk overexposure and other untoward lighting consequences. 

  2. EF-IF: Disable IF to skirt Option 1 problems and suffer shutter speeds (often < 1/15 sec) too slow for handheld work and living subjects.

  3. EF+IF: Enable IF to avoid the Option 2 shutter speed trap and then risk camera damage by covering the IF to skirt Option 1 pitfalls.

Fortunately, on closer inspection, C-2000Z in fact offers 2 additional undocumented EF-IF options that put it squarely back on the EF map: 

  1. EF-IF: Disable IF and use sequence mode to regain a workable shutter speed for HQ and SQ recording.

  2. EF-IF: Disable IF and use EF mode (if available in your camera's firmware version) to regain a workable shutter speed in any recording mode, including SHQ.

As for Option No. 3, many an RPD post has suggested covering the built-in flash with opaque tape to keep its light out of the picture, but

Marks the gotchas Firing a tightly covered internal flash can damage your camera.

RPD has seen at least one report of C-2000Z damage from heat build-up in a covered flash, and Nikon explicitly warns CoolPix 950 users of potential damage should they cover their flash.

C-20x0Z EF Option Summary

Believe it or not, the table below is the short answer to EF use with the C-2020Z and C2000Z. Entries apply to both models unless noted to the contrary. How much of this might apply to later Oly digitals, I'm not sure.

Whether or not to enable IF is the pivotal decision. Consider all the trade-offs involved before settling on any one approach. The discussions following the table will fill in the details.

Olympus C-20x0Z External Flash (EF) Options

Internal Flash (IF) Status
Enabled (EF+IF) Disabled (EF-IF)
Available shutter speeds without undocumented workarounds 1/30 sec minimum—handheld shots and portraits feasible. C-2000Z: Very slow (typically < 1/15 sec)—too slow for handheld shots and portraiture; must resort to sequence or EF mode workaround to overcome the C-2000Z's limiting EF logic.

C-2020Z: No longer an issue thanks to new explicit EF-IF menu support and a fully manual exposure mode affording the EF-IF shutter speed control lacking in the C-2000Z.

Lighting Considerations Risks overexposure, unwanted shadows,  red-eye and white highlights in subjects' eyes due to IF; may interfere with white balance (color temperature) of external lighting. Allows full external control of lighting with EF, studio lamps, etc.
Available sync methods Slave triggering off the light of the IF; no PC cable needed but flash synchronization socket can be used in lieu of slave. PC cable required for connection to the camera's flash synchronization socket; slave sync impossible by definition.
Available exposure modes All C-2000Z: Aperture-priority required.

C-2020Z: Aperture-priority or manual mode required.

Suggested techniques and  workarounds C-2000Z: Use one of these EF-IF workarounds:
  • Use sequence or EF mode for HQ and SQ recording.
  • Use EF mode for SHQ recording if available on your camera.

C-2020Z: Use the menu's EF mode or manual exposure mode to control shutter speed and aperture.

SHQ recording supported? Yes, both JPEG and TIFF varieties. C-2000Z: Only if yours has firmware (v951-81 or v951p-80 later) supporting  EF mode

C-2020Z: Yes, both JPEG and TIFF.

Slow shutter sync flash mode supported? Yes Yes
Other trade-offs Slower camera recycling due to IF recharging. (Your EF may well recharge faster.)


Exposure corrections may be necessary in close-up and certain other situations

Auto white balance failures with the IF disabled.

As we've seen above, with the C-2000Z, you're out of luck regarding EF only if you need SHQ recording with the IF disabled but lack EF mode support in firmware. With the C-2020Z, you've got it all.

EF+IF: Using External and Internal Flash Together on the C-2000Z

This most straightforward of C-2000Z EF techniques was worked out and posted in detail to RPD by Tony Collins in mid-1999. Tony wrote, 

... the aperture settings of the C2000 made it possible for any degree of exposure to be achieved with the external flash. I also verified correct operation with bounce flash.

Tony's comprehensive C-2000Z external flash article is still worth a read.

EF+IF Technique

The general idea with EF+IF is to minimize exposure time, use a subdued IF as fill, and bounce the more powerful EF to overwhelm light of the IF and fill the IF shadows.

Marks the paydirt To use external flash via socket sync with the C-20x0Z's internal flash enabled (EF+IF), 

  • Enter aperture-priority mode.

  • Set exposure compensation at EV -2.0 to dim the IF by forcing it to its lowest power setting. (If you have to compensate by increasing ISO to 200 or 400, you may want to rethink this approach.)

  • Set EF power level, beam width and bounce angle as needed. (Slave sync OK.)

  • Adjust aperture according to the EF unit's exposure table.

  • Get the fastest possible shutter speed any way you can.

With EF+IF technique, slave sync becomes possible as well.

EF+IF Tips

Marks the paydirt Pekka Saarinen at offered these C-20x0Z EF+IF tips in an RPD post:

  • Spot meter on scene highlights for faster shutter speeds.

  • Zoom in to force faster shutter speeds.

  • Decrease aperture and increase EF power level accordingly.

To that, I'd add these:

  • Increase ISO if large apertures become an issue.

  • Use manual exposure mode if you have a C-2020Z.

Marks content that should probably be confirmed independently If you're really desperate for a faster shutter speed and are willing to accept potentially large apertures, try using a slave flash in shutter-priority or automatic mode. (I haven't tested this. If you do, please let me know how it turns out.)

OK, So Where's the C-2000Z Rub?

The EF+IF approach works most of the time, but for some, the residual IF lighting effects aren't always acceptable, particularly in a studio setting.

  • Unwelcome shadows may linger

  • White balance (color temperature) may be thrown off

  • Red-eye may persist

  • Distracting white highlights may still be visible in subjects' eyes

OK, then why not just disable the IF? Because without using one of the undocumented workarounds described below, you'll get impractically slow shutter speeds—generally well below 1/30 sec—that effectively preclude handheld shots and promote blurring due to subject motion. 

And why the slow shutter speeds? Because the C-20x0Z can't detect on its own that you're using EF and the C-2000Z provides no documented way for you to tell it so. Keep in mind that by turning off the IF, you've committed yourself to using the sync socket and therefore to aperture-priority mode. Thinking that it's without flash in poor ambient light, the camera tanks your shutter speed because you've told it to leave aperture alone. Resulting shutter speeds of 1/4 to 1/2 sec are regrettably common here.

This is precisely where the C-2000Z's ostensible external flash options come up lacking, forcing you to choose between bad lighting and blurring due to motion. If only the C-2000Z had the C-2020Z's "external flash in use" menu setting to tell the camera to keep shutter speeds at 1/30 sec or higher regardless of ambient light and IF status!

But Wait—There's Hope for the C-2000Z!

As bleak as all this may sound, the C-2000Z actually has 2 different undocumented ways to simulate just such a menu item in an EF-IF setting—one a subversion of an unrelated camera feature (sequence mode) also requiring certain minimum shutter speeds, and the other an undocumented EF mode added to later C-2000Z firmware versions.  (NB: "EF mode" is my own terminology.)

To see how to take advantage of these hidden capabilities, read on.

EF-IF: Using External Flash Alone on the C-2000Z

Just when C-2000Z users were beginning to despair out loud on RPD over using EF with the internal flash off (EF-IF), Airin Kassmann* of Germany popped up with 2 very slick EF-IF workarounds achieving workable shutter speeds of 1/30 sec to 1/100 sec:

  • A sequence mode method available to all C-20x0Z owners but supporting only HQ and SQ recording, and

  • A less restrictive method based on an undocumented EF mode supporting all recording modes on the C-2020Z but available only on C-2000Zs with firmware versions v951-81 or later.

Both EF-IF workarounds are simple and quite useable. Both require aperture-priority mode and EF sync via the sync socket.

* Airin submitted both his finds to Dave Etchells of, who in turn alerted RPD readers on November 20, 1999. C-2000Z EF users are indebted to both. Shortly thereafter, the C-2020Z hit the streets.

Sequence Mode Workaround for the C-2000Z

In sequence mode, you hold down the shutter button to take rapid-fire shots until you release the shutter or fill the camera's internal memory buffer, whichever occurs first. Sequence mode just so happens to lock shutter speed at a 1/30 sec minimum at the widest angle zoom setting and a 1/100 sec minimum at full zoom, just as in EF mode below.  Sequence mode also saves you a trip to the menus by disabling IF automatically.

The beauty of this simple EF-IF workaround is its availability on all C-20x0Zs, but there's one small catch:

Marks the gotchas Sequence mode on the C-2000Z supports only HQ and SQ recording. If you need SHQ recording (either JPEG or TIFF) this workaround isn't for you—try EF mode instead.

The C-2020Z adds support for SHQ-JPEG recording in sequence mode but still can't deliver SHQ-TIFF recording. 

Using Sequence Mode

Marks the paydirt To use the EF-IF sequence mode workaround,

  • Sync your EF via the camera's sync socket.

  • Select aperture-priority mode to enable the sync socket.

  • Enter sequence mode via the camera menu. This will automatically disable the IF.

  • Specify HQ or SQ recording as desired while you're in the menu.

  • Hold down the shutter button only long enough to get one exposure.

You'll have have plenty of time to come off the shutter before the 2nd shot, even in SQ mode. (If you keep the shutter down, the camera will try to fire the EF with each exposure in the sequence, but the recharging EF will typically miss several exposures in a row before firing again.)

NB: The camera won't power up in sequence mode, even if you last turned it off there. Sequence mode supports the C-20x0Z slow shutter synchronization flash feature and works with both slave sync and socket sync.

The Undocumented C-2000Z EF Mode

Found only in C-2000Zs with v951-81 or later firmware, EF mode is an unannounced and undocumented variant of aperture-priority mode supporting EF work with the IF disabled (EF-IF) in all recording modes. Thankfully, an explicit version of EF mode was added to the C-2020Z menu, as detailed above.

EF vs. Sequence Mode Comparison

Sequence mode is available on all C-20x0Zs. The undocumented EF mode was added to later C-2000Z's, but

Marks the gotchas C-2000Zs with v951-80 or earlier firmware don't support EF mode.

EF mode supports SHQ recording; sequence mode does so only on the C-2020Z, and then only for JPEGs, not for TIFFs. Sequence mode automatically disables the IF; EF mode does not. To my knowledge, EF and sequence modes are otherwise identical in the EF context.

Using EF Mode on the C-2000Z

Access to EF mode parallels that of the C-2000Z's undocumented "long exposure" (LE)  shutter-priority mode variant supporting low-light work.

Marks the paydirt To enter EF mode for use with external flash,

  • Sync your EF via the camera's sync socket.

  • Select aperture-priority mode to enable the sync socket.

  • Disable the IF manually via the menu.

  • Press and hold the [OK] button. 

  • Rock the jog dial downward once, release the [OK] button

and you're in!

Marks the paydirt To confirm EF mode, display your shutter speed in the LCD by depressing the shutter button halfway. EF mode shutter speeds vary from 1/30 at widest angle to 1/100 sec at full (3X) zoom. Anything under 1/30 sec here means your firmware doesn't support EF mode. 

Marks the paydirt To leave EF mode, just use the camera menu to change the IF to any mode different than the one you're in.

Using the EF Menu Option on the C-2020Z

The C-2020Z's nicely implemented EF support is described above. Gone is the undocumented EF mode of the C-2000Z; the C-2020Z's [OK] button toggles manual focus in aperture-priority, shutter-priority and manual modes instead.

Don't Know Your C-2000Z Firmware Version?

EF mode first showed up in C-2000Zs with NTSC video output with v951-81 firmware. However, C-2000Zs with PAL video output destined for European markets apparently got EF mode with the v951p-80 firmware release. 

Believe it or not, C-20x0Zs store their firmware version numbers in each and every image file. To extract this and all the information stored in your EXIF image files, download Max Lyons' handy freeware EXIFRead utility or shareware Thumber application. Other image viewers like PIEACDSee, ThumbsPlus (v. 4.10 or later) and Qimage also display EXIF info, including firmware versions. 

Unfortunately, a post-purchase firmware upgrade for older C-2000Zs lacking EF mode seems unlikely at this juncture, but it could happen.  At least one RPD post reports returning a v951-80 camera for a zoom lens malfunction and getting the same camera body back with v951-81 firmware installed, so we know it can be done. And for a price, Oly continues to offer factory firmware upgrades allowing certain older models to use SmartMedia cards larger than originally supported. More at 11. 

References and Links

(See also the home page links.)

Flash Photography—one of nearly a dozen top-notch chapters pertinent to digital photography at Kodak's superb Guide to Better Pictures website.

Digital Cameras and External Flash—one of several well-written and nicely illustrated articles by Tony Collins at Tony's Digifotoinfo.

SR Electronics' Digi-Slave Flash Units—well-made flash attachments made to sync properly with digital cameras using a pre-flash,  like the C-20x0Z; nice camera brackets, too.

Unless explicitly attributed to another contributor, all content on this site © Jeremy McCreary

Comments and corrections to Jeremy McCreary at, but please see here first.