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Nikon Flash Primer

CLS – terminology and features
by Gisle Hannemyr

1. Introduction

This primer is part of a series of articles about using flash on a digital camera.

This segment deals with flash and digital Nikon cameras (DSLR system cameras and the more advanced Coolpix compact cameras) and in particular Nikon's dedicated system for controlling flash: CLS (Creative Lighting System).

Another segment covers Canon's dedicated system for controlling flash.

A third segment addresses using flash outside a dedicated framework, (i.e. non-TTL auto and manual flash, as well as non-dedicated off-camera flash).

Flash units can roughly be classified in three groups:

  1. Dedicated units made by the original manufacturer (i.e. Nikon).
  2. Dedicated units made by various third party manufacturers.
  3. Generic (i.e. non-dedicated) flash units.

Dedicated units are compatible with the manufacturer's dedicated flash system. In Nikon's case, this system is known as CLS (Creative Lighting System). Dedicated units are specially adapted to work with one particular manufacturer's system, and will not be compatible with other manufacturers' systems.

In addition to dedicated units made by the original manufacturer, various third party manufacturers such as Nissin, Sigma and Sunpak make units dedicated to work with Nikon's CLS.

Generic units are not compatible with the advanced dedicated flash control system used by dedicated units. Instead, they provide a more basic functionality, but on many different systems.

Dedicated units only offer full functionality when used with the system they are designed for. Some dedicated units will not work at all when moved to a different system. Others, when moved to a foreign environment, will “dumb down” and operate as if they were generic units.

Both dedicated units and generic units remain popular choices.

Generic flashes are often preferred over dedicated flashes for studio use. Also, generic flashes are, as a rule, cheaper than dedicated flashes with the same power output. Another advantage with generic flashes is that they may be freely moved across systems. The downside of generic units is that they lack the advanced controls and features of dedicated units.

However, getting the exposure right with low intensity fill flash is much simpler when you use dedicated flash. And dedicated flash can give you automatic power control in complex setups with multiple flashes – where some of the units even may be sitting inside soft-boxes.

Dedicated Flash

image of hot-shoe
Nikon's i-TTL hot-shoe.

In 2003, Nikon launched a new, sophisticated flash control system, known by the abbreviation CLS (Creative Lighting System). In the CLS, i-TTL is used to control the output of the flash. i-TTL replaces and obsoletes Nikon's earlier systems for exposure control known as TTL or D-TTL.

CLS is now the foundation for Nikon's dedicated flash control system. It built around a system for flash exposure control where flash exposure is controlled by the camera by measuring flash light Through The Lens (TTL).

Users familiar with Nikon's TTL on their film cameras will notice a subtle difference when moving on to i-TTL. In the case of the i-TTL, the power of the flash is not controlled during the exposure by measurement off the film surface itself. Off-the-film (OTF) measurement is not possible with digital cameras as the sensor's surface is not appropriate for measuring off. This factor, combined with the decreased latitude of the digital sensor when compared to film means that the i-TTL user must expect slightly less accuracy when using i-TTL, compared to the traditional OTF TTL measurement used on a film camera.

Instead i-TTL relies on something called pre-flash for exposure control. It works like this: The camera fires one or more low power pre-flashes milliseconds before the shutter opens. It then measures the light from this pre-flash as it is reflected from the subject through the lens (TTL). The camera uses this reading to compute the power ratio for the flash for correct exposure. The camera communicates the desired power-ratio to the flash and the flash adjust its power accordingly. Finally, the camera opens the shutter and fires the flash to make the exposure. The i-TTL system provides a fully automatic exposure control that seamlessly integrates camera and flash, but the pre-flash sequence also introduces a tiny shutter delay.

CLS is a dedicated flash system that is supported by the Nikon F6 SLR (but no other film camera) and Nikon's newer DSLR models (i.e. D50, D40, D40x, D60, D3000, D3100, D5000, D70, D70s, D80, D90, D7000, D200, D300, D300s, D700 D2-series, D3-series, and later). I am less sure of how well supported CLS is by Nikon's compact digicams. I know that some advanced models, such as Coolpix P8800 and P7000 supports at least some CLS features. To make sure what features are supported, check the manual for the particular model you are interested in.

CLS includes the following features:

  • Aperture, ISO, focal length and flash colour information communicated between flash and body.
  • i-TTL (Intelligent Trough The Lens) flash exposure control.
  • In TTL BL-mode, it makes use of focus distance with lenses capable of communicating this to the body (“D” and “G”-lenses).
  • AWL (Advanced Wireless Lighting). Wireless (by light) control of off-camera flash units.
  • FV (Flash Value) lock to obtain correct flash exposures for off-centre subjects.
  • FOLC (Flash Output Level Compensation) to get correct flash exposures for non-average subjects.
  • Auto FP (Focal Plane) high-speed sync mode to synchronise flash at high shutter speeds.
  • RPT (repeating flash) special mode where the flash fires repeatedly during a single exposure, creating a stroboscopic multiple exposure effect.
  • Slow-sync flash to force balance with ambient light in relevant exposure modes.
  • Red-eye reduction mode.
  • Rear-curtain sync mode.
  • AF-assist light (to ensure fast and precise autofocus in the dark).

Not all features are available on all compatible models. See the manuals and specification sheet for the model you are interested in for details. Below is an (incomplete) list of limitations I am aware of.

  • AWL: Some Nikon bodies (e.g. D70/D80/D90/D7000/D200/D300/D700/D800/D800E) have a built-in flash with something called «commander mode» that can act as a master for AWL. To use AWL with cameras without this feature (e.g. Coolpix/D60/D5100/D3) you either has to use a Speedlight that can be used as an AWL wireless master (e.g. SB-800/SB-700/SB-900/SB-910) or an SU-800 Remote Commander in the camera's hot-shoe as on-camera master. As an AWL remote, the SB-600, SB-700, SB-800, SB-900 and SB-910 can be set to one of three groups (A, B, or C), but some cameras only let you select one or two groups. To control all three groups, you need to use a camera that supports three groups, the SB-800, SB-900, SB-910 or an SU-800 Remote Commander.
  • FV: Setting Flash Value lock is done by by pushing a button on the camera. Only Nikon's higher end DSLRs (D200 and better) comes with a dedicated FV lock button. Some lesser models let you use custom functions to reassign buttons. For instance, on the D80, you can reassign FV lock to the generic Func-button. However, by doing so, you lose access to ISO in the view-finder (the default use of this button).

CLS works through a very high level of integration between the lens, the camera body, and one or more Nikon Speedlights. To use CLS, the lens, the body, and the flash units need to be compatible with CLS.

Note that Nikon offers two types of exposure compensation: The overall Exposure Value (EV) adjustment will affect both the exposure of the background and the output of the flash, and Flash Output Level Compensation (FOLC) that is used to modify the flash output level only.

For a list of models that can be used for dedicated flash, please consult:

Generic Flash

Generic flash units are are flash units that are not compatible with Nikon's CLS. Instead of the advanced controls of CLS, generic units are designed to fire when there is a (short) circuit between the flash's centre pin and edge.

As there is no dedicated control system for flash exposure control, the power output of generic units must be controlled by other means. Most of the generic units offer at least manual (with adjustable power ratio) and non-TTL auto exposure modes.

For a list of recommended units that can be used for generic flash, please consult our product database:

2. Exposure Modes

In order to have the scene properly lit, with correct exposure and with a good balance between foreground and background light, we need to control the amount of light put out by the light, and adjust aperture, shutter speed and ISO to match that, as well as the ambient light. In this series, the following flash exposure control modes will be discussed:

  • TTL automatic flash mode (i-TTL, D-TTL and TTL – available on Nikon Speed­lights and some dedicated third party flashes). When you are using a TTL automatic flash mode, the correct power to use for flash is determined by measuring the amount of flash light reflected by the entire scene or foreground subject through the camera lens (TTL = Through The Lens).
  • Non-TTL Auto flash mode (available on Nikon SB-800, SB-900 and SB-910 and some generic flashes). When you use a non-TTL Auto flash mode, you use a built-in sensor at the front of the flash that measures the average flash light reflected by the entire scene.
  • Manual mode (available on all Nikon Speedlights and all generic flashes). When you use a Manual flash mode, nothing measures the light, you control exposure by setting up the power of the flash by selecting how much (as a fraction of maximum output) light the flash should emit, and selecting a ISO and aperture that will yield the right exposure.

The Nikon TTL exposure mode is discussed in the next section. The non-TTL Auto exposure mode and Manual exposure mode are discussed in the segment about generic flash.


The Nikon CLS uses a TTL mode known as i-TTL. replaces and obsoletes the earlier D‑TTL and TTL systems. This note only discusses i-TTL, not the obsolete version of Nikon's TTL.

TTL is based upon measuring the flash light reflected from the scene through the camera's lens. The measurement is done by firing a low-power pre-flash. The delay between the pre-flash and actual flash is so short that the human eye is not able to distinguish between them. (However, the pre-flash will trigger plain optical slave flashes, so in order to use this type of slave flash, you need to disable the pre-flash.)

When the pre-flash fire, the light reflected by scene is picked up by one or more sensors inside the camera. These measurements are used to compute how much power to use for the actual flash.

CLS offers two different TTL-modes, known as “TTL” and “TTL BL”.

If you're shooting with the flash connected to the hot-shoe, you choose which of these to use with the flash's mode button. As soon as you start using advanced wireless flash (AWL) in TTL mode, the system will use TTL BL, whether you like it or not.

For a examples on how to use these modes, see the sections on TTL and TTL BL in a later segment of this series.

The big advantage of TTL is that because TTL measures reflected light through the camera's lens, the position of the flash (or flashes) does not matter. The flash may be bounced, in or out of the hot-shoe, facing away from the camera or even put inside a soft-box. The set-up may involve multiple flashes controlled by AWL. No matter what, TTL metering means that the camera meters the actual scene as seen through the lens. The sensor on an non-TTL Auto flash may “see” the wrong scene in many situations where the flash is off-camera.

3. Off-camera Flash

To move the flash off-camera, you can use wires or a wireless setup. For a wireless solution, you can either use Nikon's Advanced Wireless Lighting (AWL), that is part of CLS, or you can use a generic solution using wires, plain optical slaves, radio control, or a combination of all these.

Dedicated Wired Flash

To move a single Speedlight off the camera, you can use a Nikon TTL Coiled Remote Cord (SC‑17, SC‑28 or SC‑29) or a compatible third party cord.

Each of these cords are about 150 cm long. The difference between them is that the SC‑28 has a better lock than SC‑17, and that SC‑29 also works as an external AF-assist light for placement of a flash off-camera. These are just extension cords and preserves all flash functions including i‑TTL (i.e. the flash works like it has been mounted directly in the camera's hot-shoe). Their main use is for mounting a Speedlight flash on a flash bracket.

For multiple off-camera flashes, with CLS there is no longer an option to use wires. The legacy wired solution that Nikon provided for pre-CLS TTL is described here.

For CLS-compatible cameras and flashes, Nikon instead provides a sophisticated wireless system for controlling multiple off-camera Speedlights. This system is described in the next section.

Dedicated Wireless (light based) Remote Flash

Nikon wireless flash system let you can fire two or more Speedlights together without any cables linking them. This dedicated wireless system is called AWL (Advanced Wireless Lighting) by Nikon. It uses infrared light for signalling.

In both the SU-800 Remote Commander and ordinary Speedlights (such as the SB-910) there is a xenon flash tube. As evident from the diagram below, a xenon flash tube has a fairly linear output in the range of visible light (400 nm to 700 nm), very similar to natural sunlight. But xenon also has a very powerful output in the near infrared region above 800 nm. This makes it well suited for using infrared light for control.

Typical spectral frequecies produced by a xenon flash tube.

The AWL receiver has a filter in front of it that blocks visible light and lets infrared light pass through. The SU-800 Remote Commander has a similar filter in front of the xenon tube to stop it from emitting visible light. Obviously, there is no such filter in place on ordinary Speedlights, but it is only the infrared component of their output that reaches the wireless receiver on the remote Speedlights.

According to Nikon's AWL compatibility chart, the following definitions are used to describe the AWL units:

master unit:
Works to control remote Speedlight units by firing flash during exposure.
Works to control remote Speedlight units without firing flash during exposure.
remote unit:
Fires flash only when triggered by a master unit or a commander.

However, Nikon literature also say that “commander mode” means using the “built-in unit as master” (e.g. D80 manual, p. 96). In most of its literature, Nikon seems to use the terms “commander” and “master” interchangeably.

To use AWL, you have the following options:

  • Use your camera's built-in flash in commander mode (note that the Coolpix models, and entry level DSLRs such as D60 and D5100 do not have commander mode, and that the professional models D1 … D4 do not have a built-in flash).
  • Have a dedicated flash capable of acting as an AWL master (e.g. the SB-910) in the hot-shoe (or connected via a TTL Coiled Remote Cord).
  • Have the remote commander transmitter SU-800 in the hot-shoe.

When using AWL, the commander uses infrared light to exchange coded signals with one or more remote units. The coded signals, which can involve several pre-flashes, occur so rapidly between the time shutter is pressed and the main flash fires that the entire sequence appears to be a single sustained flash.

The AWL control system lets the photographer select one of four channels. This is to minimise the risk of interference from other photographer's equipment. No other flash from the other photographers present will be able to trigger yours (apart from another Nikon commander set to the same channel). This is very handy if you have to work at social gatherings or weddings where a lot of people fire their compact cameras with flash.

The AWL control system also let the photographer control up to three groups. There may be multiple Speedlights in each group, and each group may be assigned a different power setting or fired in different modes. The ability to control multiple groups vary between models. The built-in flash of the D70/D70s can only control a single group, and the built-in flash will only contribute a tiny amount to the exposure in commander mode (Nikon says none, but that is not strictly true). On the D80 and better, or if you use a flash with a built-in commander mode, such as SB-910, or SU-800 wireless commander, as master, you can control the power of the master flash as well as the remote units in up to three groups.

While there is no hard limit to the number of flashes that can be controlled remotely, Nikon warns that in i-TTL mode, more than three flashes in a group may interfere with each other.

If you want to control a large number of wireless flashes, or you don't want pre-flash to interfere with the scene, you may consider using plain slave flash instead of AWL. The reach of the master is also greater in plain slave mode. This is discussed in the segment about plain optical slave triggers.

Nikon's wireless flash control system works well indoors. In the SB-910 manual, Nikon tells you to place all remote units within 30° (on each side) of the master, to place them at distances between 5 and 7-10 meters, and to make sure that there is a clear line of sight between the master and the remote units. These are extremely conservative figures. For outdoors use, you may need to operate within these limitations (and you may still experience reliability problems in bright sunlight). Indoors, where the signal light can bounce of bright surfaces, placement of remote units can be more flexible than Nikon's literature let you believe.

If you are placing your remote units at an obtuse angle, make sure you change the zoom head of the master to a wide enough coverage.

Note: While the built-in flash of Nikon entry-level bodies (e.g. D50, D40, D40x, D60, D3000, D3100 and D5000) can not be used as an AWL master – they work fine as a plain master (i.e. outside the AWL framework).

Blocking All Visible Light

According to Nikon, the built-in flash can be set to act as commander only, and not contribute any light to the scene during exposure. This is the only mode available on the D70, while on D80 and newer, you do this by setting mode “--” for the built-in flash.

In reality, things are a little more complicated. If you check this out in a mirror, you'll see that the built-in flash emits a tiny glow during exposure (the IR component of that glow is what controls the remote flash). This tiny glow is too insignificant to pose a problem in most cases, but in macro photography, or if mirrors or other shiny surfaces are involved, it might be a problem.

One solution to this is to fit the Nikon SG-3IR IR panel. It will remove the visible component from your built-in flash (it looks like solid plastic, but it lets IR through). According to Nikon, it is made to fit the D70, D70s or D200. However, users of the D300 say it works fine, and it it will probably work on most Nikon's DSLRs (Exactly which models it fits, I do not know. Use the comment field below this article if you have any experience to contribute.)

However, if you are frugal you can make a makeshift IR-pass filter by taping black unexposed E6 developed slide film in front of the built-in flash. Black unexposed slide film is transparent to IR light, but blocks visible light. (Somebody wrote to me and said that instead of slide film, you could use material cut out out from an old floppy disk, as this material too is transparant to infrared light. So far, I have not been able to use this method succesfully.)

Dedicated Radio Flash

Nikon's own system for dedicated wireless flash (described above) is based upon the commander using light to signal the remote units.

Some third party vendors offer dedicated systems that use radio instead of light to signal remotes. Below are links to more detailed descriptons of dedicated radio flash systems:

Generic Off-camera Flash

For working with multiple off-camera flashes, AWL works fine in many situations. However, there are situations where you will not want to use it for off-camera flash. For instance, if you want greater range, when you are working with monolights or in some other environment where AWL is not an option, or when you are using a non-compatible lens. In these situations, you will use generic wired, plain optical or radio slave flash instead.

Nikon refer to plain (non-AWL) optical slave flash operation as SU-4 type wireless multiple flash, after the wireless Slave Flash Controller SU-4. The “multiple” part of the designation means that the SU-4 that the SU-4 will trigger multiple flashes on the flash when the master is operating in the RPT (repeating flash) special mode (I've only found this to be reliable up to around to around 10 Hz.

The physical SU-4 unit belongs to the film era. In manual mode, it will still work as a plain optical trigger for a modern Nikon flash lacking a built-in plain optical trigger, such as the SB-600. However, the main feature of the SU-4, the Auto mode that would quench the remote flash when the TTL logic controlling the master flash switches the master off, can no longer be used. For this to work, the master need to use OTF TTL, which does not work on a digital camera. So on a DSLR, the SU-4 can only be used with Manual mode for exposure control. Unlike third party optical triggers, the SU-4 may not work with non-Nikon flash units.

Today, the SU-4 mainly lives on as a special wireless mode on Nikon's most advanced Speedlights . Selecting this mode turns a SB-700, SB-800, SB-900 or a SB-910 into a plain optical slave.

Note: The pre-flash measurement system is employed in TTL BL, TTL and AA modes. In all three of these modes, wireless triggering of plain optical slave flashes cannot be used, as the pre-flash would trigger the slave prematurely.

For more about using generic off-camera flash, see the segments discussing third party options.

How to use the SB-700, SB-800, SB-900 or SB-910 as a Plain Optical Slave

(This section is not about remote control using commander mode.)

The Nikon SB-700, SB-800, SB-900 and SB-910 Speedlights has something called SU-4 mode where their integrated optical receiver emulates Nikon's pre-AWL optical trigger (which was named “SU-4”). In this mode, the speedlights behave as plain optical slaves. This means that you can trigger them with the built-in pop-up flash of the Nikon D40, D50, D60, D3000, D3100, D5000 and D5100 (which does not support AWL's commander mode) or with any cheap manual flash.

Here is how you activate SU-4 mode on an SB-800:

  1. Press and hold the Sel button on the back of the flash for 2 seconds, or until the custom functions emnu appears, to get into custom settings.
  2. Use the multi selector to get the upper right quadrant (wireless operation) highlighted and push the Sel button again.
  3. Press down button (-) until “SU-4” is highlighted and push Sel again to select.
  4. Press On/Off button to get out of custom settings.
  5. Your flash will now say “REMOTE.”
  6. Press the Mode button to toggle between automatic and manual. Choose manual.
  7. Set power. By pressing the + or - buttons, you can change power in 1/3-stop increments. There is no i-TTL-control in this mode.
  8. Pop up your camera's built-in flash and set it to manual. (NB: You can not use commander mode .)

The light sensor of the optical receiver is behind the round window next to the battery door on the left side. For best sensitivity, you will want to rotate the flash body so this window faces the master flash.

To activate the SU-4 mode on an SB-900, see our SB-900 cheat sheet

I haven't got a SB-700, but it has a similar capability. Plese see the manual for details.

To trigger the slave flash in SU-4 mode, you need your lead flash to be in manual mode (i.e. you must turn off i-TTL). If your lead flash fires a pre-flash, the slave flash will fire, but before the shutter opens. In that case, the slave flash will have no effect.

If you use SB-700, SB-800, SB-900 or SB-910 as a master in SU-4 mode, Nikon tells you it can reach up to 40 meters (as opposed to 10 meters in AWL mode). Again, these are conservative figures and greater distances are often possible (but with reduced reliability).

4. Choosing a Flash

What type of flash should you buy? Below is some points to help you decide, but only you know your requirements.

As we've seen, there are three types of flash to choose from:

  1. Dedicated Nikon models.
  2. Dedicated third party models.
  3. Generic flash models.

Dedicated units made by Nikon are designed to work with your Nikon camera.

Dedicated units that are designed by third parties are also supposed to be tailor made to work with your Nikon camera, but at a lower price point.

Both Nikon's dedicated units, and dedicated units made by third parties, are designed to communicate with your Nikon body, and should be able to pick up ISO from the body and aperture from a compatible lens. They should also monitor the shutter speed and make sure you don't exceed the x-sync speed unless you are in Auto FP mode. Some third party dedicated units do these thing less than perfect.

In general, using Nikon's CLS with a dedicated Speedlight or Speedlights allows you to hand over control of exposure and power to the flash, even in diffucult fill-light situations and when working with off-camera flash, soft-boxes, snoots, etc.. This means that you can consentrate on composition, framing and shooting, and feely change aperture and ISO, without worrying about the flash.

Generic flash units with Auto mode will also control flash power and therefore exposure for you. However, a non-dedicated flash will have no idea about the ISO and aperture in use. This means you need to transfer those “by hand”. Also, they do not measure the ambient light and can not provide automatic fill flash in auto mode (but most of these also offer Manual mode, which can be used for fill). Since exposure control is done with a sensor on the flash itself, they may not provide accurate exposure control when used out of the hot-shoe, i.e. when the sensor is not aligned with the lens.

Generic flash units that only offer Manual mode requires the use of a separate flash meter or cumbersome guide-number calculations to nail exposure. Because power must be explicitly set on the flash, manual flash works best in a studio environment were you set the power-ratio on one or more manual flashes placed on light stands. Then the distance between the scene and the flash or flashes remain constant, and you can keep using the same power ratio as long as you also keep using the same aperture and ISO. If you want to have your flash in the hot-shoe and move around, so that the distance between flash and subject constantly changes, manual flash may be quite cumbersome to work with.

For fill flash, dedicated TTL-flash is at its best, and non-TTL Auto flash useless. With Manual flash you can at least set a power ratio suitable for fill flash if you want to.

If you buy a non-dedicated flash and intend to use it in your camera's hot-shoe, you also need to consider trigger voltage safety.

I think it is safe to say that you can not go wrong with a Nikon dedicated Speedlight. All the current units have good reputations. The SB-400 is a compact and lightweight alternative without many bells and whistles. The SB-700 is for those that want more power and AWL as an option without paying a premium. The SB-910 is the top of the line model with extra power and some unique functions.

The downside of Nikon's dedicated flashes is cost. They usually cost more than third party dedicated with similar specifications, and they may cost more than three times as much as generic flash units with equal power output. If you want a bright flash to be your main light, then you can save some money by choosing a generic flash. For instance, the dedicated Nikon Speedlight SB-700 (GN 28m) carry a sticker price of around USD 330. More powerful generic flash units such as the Vivitar 285HV (GN 31m) or YongNuo YN-560 (GN 39m) will cost only about USD 80-100 brand new, and used models can be had for a lot less than that.

The i-TTL system provides a fully automatic exposure control that seamlessly integrates camera and flash, but the pre-flash sequence also introduces a tiny shutter delay. For instant response (e.g. skateboard photography), you may be better using a dedicated flash that also gives the option of using a non-TTL mode such a manual or non-TTL auto, or just use non-dedicated flash units.

There are third party dedicated flashes from Metz, Quantum, Sigma, and others. Currently, I know little about the compatibility and quality of these units, so if you consider one of these, make sure you check it out is the store before committing to a purchase.

Power matters. Whether you choose a dedicated or non-dedicated flash, if you intend to use bounce flash, I would not recommend a unit with less power than the Nikon SB-700 (GN 28m) or a Vivitar 285HV (GN 31m). Be warned that a flash with a GN as low as 28m or 31m can only be bounced in small rooms with a low, white ceiling. Depending upon imager sensitivity, room size, distance to ceiling, ceiling whiteness, etc. you may need even more power than the Nikon SB-700 affords to get good results with bounce flash.

Manual only flashes are going out of fashion, and while stock remains, they can be picked up from bargain bins for next to nothing. A number of perfectly working manual flash units can be had for small change at eBay and garage sales. Recently, Chinese manufacturers has started supplying brand new manual only flashes such as the Yong Nuo YN460 at quite low prices.

If you learn how to use a manual flash, you may save a lot of money by being able a reuse any old flash unit you may have left over from your film days, a cheap manual flash you may buy at a sale, or a new Chinese unit. If you buy an inexpensive handheld flash meter, you'll have no trouble getting the right exposure, even in complex situations involving fill light or multiple flashes. If you don't want to buy a flash meter, you should be able to pick the correct aperture for a manual flash from tables of guide numbers and subject distance. This may sound awkward, but it is not difficult after you've gotten used to it.

However, if the manual flash have no variable power setting, your options for controlling the light will be limited. Also, metering a test flash, or using guide-number tables may slow down your action. If you don't want to go through these steps, make sure you buy an CLS capable dedicated flash or a auto flash.

Legacy equipment

This section gives a brief overview over to what extend legacy equipment is compatible with modern Nikon cameras and flashes.

Nikon pre-CLS flashes and cameras

It was not until the Nikon F4, in 1988, that Nikon started using an ISO-compatible accessory shoe. For the models prior to this, Nikon used a proprietary hot-shoe and the flashes built for this (e.g. SB-2 for the F2, and SB-12, SB-16A, SB-17 for the F3) can only be connected to a modern body via an adapter or via the PC-socket.

Nikon's older series of Speedlights with ISO compatible accessory shoe (e.g. the SB‑15, SB-16B, SB-24, SB-25, SB-26, SB-27, SB-28) will fit in the accessory shoe of a modern camera, but do not support the CLS. The more advanced models supported a mode of measurement just called TTL. In this mode, measurement of flash output was done in real time measuring light reflected off the film (OTF). Unfortunately this mode of measurement can not be used on digital cameras.

OTF measurement is not feasible for a digital sensor (because the shiny surface of a digital sensor is not suitable for metering), so for the early digital models, Nikon first came up with something called D-TTL. D-TTL (like i-TTL) uses the pre-flash method to compute exposure. Flashes that supports D‑TTL carry a DX suffix (e.g. SB-28DX, SB‑50DX, SB-80DX). D‑TTL was the flash exposure control system used on the D1-series and the D100. It had a reputation for being somewhat unreliable for exposure control. D‑TTL is not available on most recent Nikon DSLRs, and the Speedlights carrying the DX-suffix must now be considered obsolete. (The F6 SLR and the D2-series DSLRs are the only cameras that let the user use both i‑TTL and D‑TTL.)

While CLS features such as i-TTL, AWL, FV, AF-assist and Auto FP do not work on these older flashes, many of the older Speedlights are still usable with modern DSLRs in Manual and non-TTL Auto (provided they offer these modes). In Auto mode, they give reliable exposure control when used for flash key. However, unlike the Auto Aperture mode featured on the SB-910, they don't pick up ISO, aperture and focal length from the body. That means that for the exposure control to work right, you have to manually set the ISO and aperture on the flash to match your camera settings. If the flash has a zoom head, and you want the zoom head to match your FOV, you have to set that manually as well. This is workable, but cumbersome.

If you are interested in using older Speedlights off-camera, see the segment about generic off-camera flash.

For more detailed information about compatibility, Nikon camera manuals list what modes of older flashes are supported on newer cameras (e.g. D80 manual, p. 120). For detailed information about a particular configuration, refer to the relevant manual.

Note that for the SB-27 to work in non-TTL Auto mode on a modern DSLR, it must be placed in Forced A mode. (To do this, switch the flash mode selector from “off” to “auto” while holding down the “zoom” button. The “A” indicator in the LCD panel will blink to indicate that the SB-27 is in Forced A mode. See p. 70 on the SB-27 user manual for an illustration.)

TTL-support and older cameras

The SB-600 and SB-800 Speedlights also supports the older D-TTL and TTL modes. The SB-800 also have a socket for the legacy Nikon TTL sync cords (SC-18, SC-19) and the legacy SU-4 mode. This means that you can buy these flash units for use with older cameras as well as new. Legacy support is mostly dropped from the SB-700, SB-900 and SB-910.

To find out whether a particular Speedlight is compatible with the TTL mode (D-TTL or OTF TTL) of an old camera, you need to refer to the documentation for both the flash and the camera.

Final remarks

If you intend to use several flashes in a wired or wireless setup, you need to think careful about your options. For a wired setup you're better off with flashes with a pc-connector (otherwise, you need to buy adapters as well). For a wireless setup, you need to decide whether you want to use the CLS wireless system, or to use third party devices built around optical or radio receivers. Not all flashes are compatible with all types of receiver, so if you build your wireless system from components from several sources, you need to make sure that the units are compatible before you buy.

When buying second hand, make sure: 1) That the flash you buy is compatible with your camera with respect to trigger voltage, electrical connections, and operational modes; 2) that the battery compartment is clean and the contacts free of corrosion; 3) that the body, including the foot, is mechanical sound and free of cracks; 4) that the recycle time is reasonable with fresh batteries; and, 5) that the colour temperature has not shifted (photograph a WhiBal-card or a neutral grey surface, locking the camera's white balance on “flash” and make sure that the RGB-values are reasonable neutral.

5. Read More

The article you are reading is part of a series about dedicated flash for Nikon cameras. Here is an overview of the series:

6. Flash links

Digital Darrell:
Nikon D200 and Nikon's Creative Lighting System (Detailed AWL tutorial with the D200 and the SB-800 or SB-600.)
Mike Hagen:
Using the Nikon Creative Lighting System. (Ad for a 193 page eBook about using the SB-600 and SB-800, including a 15 page sample (PDF.)
David Hobby:
Strobist (Great blog about Nikon flash use and lightning in general by Baltimore based photojournalist David Hobby.)
Thom Hogan:
Nikon Speedlight Specifications (A table with detailed comparison of the specifications of all recent Nikon Speedlight models.)
Russell MacDonald:
Nikon CLS Practical Guide (Blog focusing on the practical use of Nikon's CLS.)
Joe McNally:
Blog (CLS expert and author of The Hot Shoe Diaries: Big Light from Small Flashes.)
Neil van Niekerk:
Flash Techniques (Tutorial on flash photography for weddings and portraits.)
Photographic Accessories (PDF with 11 pages about CLS usage and accessories.)
The World of Nikon Speedlights (Nikon official site with tutorials and examples.)
Oleg Novikov:
Nikon Creative Lighting System review (Brief introduction to CLS.)
J. Ramón Palacios:
Flash Guide – The Teddy Bears Test (37 test shots of same subject varying flash set up – indoors and outdoors.)
Ralph Paonessa:
High Speed Sync for flash at any shutter speed (Introduction to FP flash use for Canon and Nikon)
Moose Peterson:
The TTL Flash System (Pre-CLS intro to using Nikon flash.)
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12 responses:

SU 800 & Nikon F4

I just would like to clarify whether the CLS-system and SU 800-remote commander are compatible for use with the Nikon F4 SLR Camera Body?


F4 is not CLS compatible

Sorry, Nikon F4 is not compatible with CLS and will not be able to use the SU-800. The Nikon F6 is the only film camera compatible with CLS.

Great explanations

Thanks Gisle. as a budding strobist with some good Nikon gear I found your explanations really clear and 'illuminating'. without being too technical you have helped me understand better what TTL is and how flashes interact with the camera, the lens and other flashes.

Many thanks!

Using old nikon auto flash with D5100

I have the model 22 Nikon flash unit - an older auto flash, not compatible with I-TTL.

It has a 'motor drive' mode that enables up to four reliable multi flash lit shots if I set my D5100 to a multishot drive mode i.e. I can rip off 4 shots reliably with flash on each one. It runs out of power by the 5th exposure.

I thought I'd share this info as I think it is a very useful feature for such an old flash unit.

Nikon D90 camera RPT (repeating flash)

I have a D90 camera. After fixing the RPT menu, the RPT function is not happening in my camera in built flash. All other menu functions are perfectly working. Would you kindly let me know what may be the problem or am I not doing the menu correctly or some thing otherwise wrong? Kindly reply. Regards.


On the Nikon D90, you should be able to set up repeating (stroboscopic) flash for the built-in flash by selecting “RPT Repeating flash” in the D90 Bracketing/Flash menu (e2). Note that this option is available in P, S, A and M modes only.

RPT flash: menu e2

After selecting the RPT function, you should see the menu shown on the left. This let you set the RPT parameters: The output strength, times to repeat, and frequency. After pressing the OK button, the built-in flash should indeed repeat as long as you stay in one of the modes P, S, A or M and the shutter stays open.

Also make sure you use a long enough shutter speed for the stroboscopic effect to work. For instance, if you want to fire 10 flash strobes with a frequency of 10 Hz (= 10 strobes/second), you should use a manual shutter speed equal to 10 x 1/10 = 1 second.

What is happening when you try this on your Nikon D90: No flash at all, or only a single flash when you press the shutter?

SB800 master with 2 SB80 optical slaves all off camera without wire or PW's. Possible?

I want to use my SB800 as a master to trigger 2 SB80's optically but I also want to have the SB800 off camera. Can this be done without having to wire the SB800 or use transmitters like PW's?

Is the only option to use pop up flash obscured / re-directed away from scene but visible enough to trigger all 3 flashes optically or should i just PC port my SB800?



if you can get your SB-800 to fire off-camera, it will work fine as lead flash that will trigger the two other flashes optically. So all you need to do is to get the SB-800 to fire. There are three ways to do this:

  1. Use the camera's pop-up flash to trigger the SB-800. To stop it from contributing to the exposure, you can obscure or redirect it (as you suggest yourself). To obscure it, Nikon offers a device known as the SG-3IR IR panel. It will completely remove the visible component from your built-in flash, but let through IR. It is the IR that triggers the SB-800. You must set the pop-up flash to fire in manual mode. Otherwise, the i-TTL pre flash will set off the SB-800 to early. Also: Do not use “commander mode”.
  2. Use a radio trigger to trigger the SB-800. It does not have to be something as expensive as a PocketWizard. YoungNuo and others make reasonable priced triggers that work well unless you want to use them in wet conditions. See our review of YongNuo radio triggers.
  3. Use a cord.

You had this one mostly worked out yourself, but I hope it is helpful to know that you only have to worry about triggering the SB-800. When the SB-800 fires, the rest will follow if set to SU-4 mode.

Remote Repeating Flash Technique


I do have D700 and two SB800. I would like to execute repeating flash remotely from D700. I will press the shutter one flash indication from my built-in flash and that will trigger two remote flashes [may be both on group A channel 3] - is this at all possible?

Please let me know.



Sunpak Auto 555 with D7000/7100

The title gives away my question. I have an older flash unit, the Sunpak Auto 555 handle-mount flash. Although an "auto" flash that I had previously used on my old FE2, will this flash work, and in which modes will it and will it not work, on the newer DSLRs? I'd rather not shell out hundreds of dollars for a new flash if I don't have to.





1-NISIN 622



Premature flash

My D700 seems to inadvertently trigger my speed light (SB910 or SB900). Which causes me to miss shots using the flash...(meaning I don't get a flash) because it had already fired several times...

However, when I put either speed light on my D300 I do not have this problem.. Can this be a contact problem with the speed light and the camera?


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