nikon flash use

7/27/2019 Nikon Flash Use

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Nikon Flash UseMore Settingsby Gisle Hannemyr

1. Introduction

Nikon DSLR's and dedicated flash units has verysophisticated control with a number of modes andsettings. Some are set on the camera. Others are set onthe flash. This note has put a description of all of them inone place.

2. Modes set on the Camera

Some of the flash modes are set on the camera, ratherthan on the flash. To set most of these modes on aNikon D80, you keep the flash button depressed androtate the main (rear) command wheel to cycle throughthe modes. The modes appear in the flash frame in thetop LCD panel on the camera.

To set Auto FP on a Nikon D80, you need to go into thecustom setting menu (#25).

For setting the flash modes on camera or other NikonDSLR models, see the camera's instruction manual.

Slow-sync Flash

The default shutter speed when using flash is 1/60second (you can change this default on a D80 withcustom setting #24). The flash will use a faster shutterspeed if the ambient light requires it, but will not normallygo below 1/60 second in the modes where cameracontrols the shutter speed.



When slow-sync flash is activated (on a D80, you setthis by pressing the flash button and turning the maincommand wheel until the word “SLOW” appears on the

camera's top LCD), shutter speeds as low as 30seconds may be used to obtain the correct exposure forboth the main subject in the foreground lit by the flash,and the background, in low-light situations or at night.

For slow shutter speeds, you may need to use a tripod toavoid camera shake.

In the Night Portrait scene mode, slow-sync flash isautomatically activated.

Rear curtain Sync

Normally the flash fires at the same time the shuttercurtain opens (i.e. front curtain sync). When rear curtainis activated (indicated by the word “REAR” on the

camera's top LCD), the flash fires just before the shuttercurtain closes.

Rear curtain sync may be selected when one is shootingfast-moving subjects at slow shutter speeds. With frontcurtain sync, unnatural-looking pictures can occurbecause the blurred movement appears to be in front of

the subject frozen by the flash. Rear curtain sync createsa picture in which the blur of a moving subject (forexample, the taillights of a speeding car) appearsbehind the frozen subject. The difference is illustrated with thetwo images below.



Left: Normal (front curtain) sync. Right: Rear curtainsync.

Rear curtain sync automatically enables slow-syncmode, since the only time you should want to use rearsync, is when you also set a slow shutter speed tocapture blurred movement.

Using rear curtain sync with shutter speeds faster than1/30 second is not recommended. Rear curtain syncintroduces a delay between the pre-flash and the mainflash lasting the length of the exposure. This delay gives

most people just enough time to react to the pre-flash.Using rear sync for portraits is a sure way to make yoursubjects blink or squint.

Rear curtain sync can not be combined with AWL, orwith the FP or RPT modes.

Red-eye Reduction Mode

When this mode is activated (indicated by an eye-symbol appearing on both the camera's top LCD and theflash's rear LCD), the flash fires three flashes at reducedoutput just before the picture is taken. This makes theiris of humans and animals contract which reduces thearea where the red eye effect can be seen. It also

introduces a shutter delay to allow the subject's irisestime to react.



The red-effect only occurs when you use the flash askey light pointing forwards and directly into the subjectseyes. Later on in this series. when I discussdirect flash

use, I'll tell you that you should avoid using your flashlike this. I also think that the red-eye reduction mode isonly moderately successful in removing red-eyes, andthe shutter delay is annoying, so I don't use this mode.

But try it out! Perhaps you find more use for it than me.

Auto FP

FP (Focal Plane) is a syncmode that let you synchronise flash with higher shutterspeeds than the camera's normal maximum flashsynchronisation shutter speed (often called“x-syncspeed”).

To use this mode on a Nikon DSLR, you need to have aCLS-compatible flash unit connected to the camera'shot-shoe, and you must enableAuto FP on the camera(custom setting #25 on the Nikon D80). Without havingAuto FP enabled, the camera will not let you set theshutter speed higher than the x-sync speed when you

use a CLS-compatible flash. With Auto FP enabled, youcan use any shutter speed.

In FP mode the flash will not fire once, but many times atan extremely rapid rate (typically 50 KHz) which beginswith the opening of front curtain of your camera's focalplane shutter and ends with closing of rear curtain. Thispermits the correct exposure to be obtained as the



travelling slit of a dual curtain shutter passes over thesensor at high-speed.

Note that using FP reduces the maximum power of theflash. The only way to have FP is to illuminate the focalplane curtain, which, depending on the shutter speed,may cover a very large percentage of the focal plane.This means that the higher the shutter speed is abovethe shutter's x-sync speed, the smaller the area of filmthat gets illuminated by each flash.

The table below shows approximately how much themaximum power expressed as guide number GN isreduced when an SB-900 is used inFP mode on a NikonD80. It has full power (GN 34, ISO 100/meter) at the X-sync speed (1/200 second), is reduced by -1 EV (halfpower) at 1/250 second, and then by another -1 EV foreach doubling of shutter speed. At 1/4000 second it is

reduced by -5 EV, or 1/32 of full power.

Shutter Speed GN Power

1/200 34 0 EV 1/1

1/250 22 -1 EV 1/2

1/500 16 -2 EV 1/4

1/1000 11 -3 EV 1/81/2000 8 -4 EV 1/16

1/4000 6 -5 EV 1/32

Using FP will reduce the effective GN of the flash whenyou exceed the x-sync speed. However, it has no effectat speeds lower than the x-sync. It does no harm to haveAuto FP permanently enabled.



On a Nikon Speedlight, the FP mode can be activated inthe following flash modes: TTL, TTL BL, AA, M and GN .On the Nissin Di866 the FP mode only works in

TTLmode.

Note: The FP mode is mainly useful when you want touse large apertures when doing fill flash in brightdaylight. The FP mode does not help you freeze motion.Normal flash photography is very good at freezingmotion, since a burst of electronic flash is so incrediblybrief. When the dominant light on a scene is a very short

flash of light it is almost as if you used a very highshutter speed in the thousandths of a second. Howeverwhen you use FP mode flash, the flash unit pulses thelight output over a longer period of time in order tosimulate a light being lit for the entire time the shuttertravels across the focal plane. Since the flash burst is nolonger very short, it becomes more difficult to freeze

motion, even with high shutter speeds. And because theFP mode makes you lose so much of the power of theflash, it is not very useful when you want the flash to bethe dominant light. For high speed flash photography,you instead use manual mode, and adjust the powerratio to make sure that the flash burst is short enough to“freeze” movement. For more more about this technique,

see below.

High Speed Sync Without Auto FP mode

Not all Nikon DSLRs support FP mode. However, thefollowing DSLR models: D70, D70s, D50 and D40 willsync with mostgeneric flash units at any shutter speed(i.e. up to 1/4000 second). This is because these models

use a CCD sensor that works as an electronic shutter at



high shutter speed. A conventional mechanical shutter isonly used at shutter speeds below 1/125 second.

For some reason, Nikon has put in a program limitationthat will not let you set faster shutter speed than 1/500second in these models if you mount adedicated flashunit in the camera's hot-shoe. You can get around thislimitation by taping over the two metal contacts on theback of the Speedlight.

3. Speedlight Flash Modes

Speedlights offer a number of different modes (not allSpeedlights let you set all these modes). Here is asummary of the modes you may come across:

• TTLo TTL (Through The Lens): The light from a pre-

flash reflected by the centre subject is metered

by a sensor in the camera and flash power isadjusted accordingly to expose the centresubject is correctly.

o TTL BL: Like TTL, but the algorithm used by thein-camera computer to figure out the flashpower setting is more complex and takesadditional data into consideration.

• Autoo A (Auto): The light reflected by the scene is

metered by a sensor inside the flash itself andthis measure used to determine flash powerlevel.

o AA (Auto Aperture): The same as A, butautomatically adjusts the aperture setting on

the flash to match the aperture on the camera.• Manual



o M (Manual): The flash power level is setexplicitly by the user.

o GN (Distance Priority Manual): The power level

is derived from the distance to main subject, asset by he user.o RPT (Repeating): Like M , but the flash fires

repeatedly during a single exposure.

How these modes operate are described in more detailbelow:

TTL

When the flash is used in TTL or TTL BL mode, a low-power pre-flash is fired prior to exposure and before theshutter opens. The light generated by this pre-flash ismeasured by a sensor inside the camera (i.e. Through The Lens ). A computer inside the camera computeswhat power from the flash is required for correctexposure. Then the shutter opens, the exposure ismade, and the shutter closes.

All this happens so fast that you'll not be able to tell theflash apart from the pre-flash (but unfortunately not fastenough to stop people with fast reflexes from blinking inresponse to the pre-flash).

In some situations, the photographer may have a choicebetween two different TTL modes:

If you're shooting with a Nikon Speedlight SB-600, SB-800 or SB-900 connected to the hot-shoe, there is twoslightly different TTL-modes to choose from: Plain TTL mode, and TTL BL mode. You should pick the plain TTL

mode if you use spot metering, and TTL BL mode if you



are using matrix or centre weighted metering. The NikonSpeedlights SB-400 and SB-700 automatically sets theTTL mode that best matches the light metering mode set

on the camera. If you're using advanced wireless flash(AWL) in TTL mode, the system will always use TTL BL.

Plain TTL

In the plain TTL mode, the camera's

standard exposure meter measures the ambient lightusing the light meter mode selected on the camera. Thecamera uses this measurement to select the exposuresettings for the camera, such as aperture and shutterspeed in the non-manual exposure modes. It will do thiswithout taking into consideration that flash will be used.Also, the camera will make a separate centre weighted

measurement of the reflected light from the pre-flash. InTTL mode, this measurement alone is used to computethe power to use when the flash is fired. In TTL mode,the metering of the pre-flash is heavily biased towardsthe centre. The active focus point is ignored. This meansthat for flash metering to be correct, your main subjectneeds to be central, or you need to use FV lock (withmain subject central) and then recompose.

In plain TTL mode, the two measurements will not beinterfere with each other. The flash output power, andthe shutter speed and/or aperture setting (depending onexposure mode), will be decided by separatecomputations. Also in plain TTL mode. distance data, asreported by G- and D-lenses, is not taken into account

when computing flash power.



When you are using the flash in plain TTL mode, theflash metering system does not take the ambient intoaccount when determining how much light to put out.

However, the ambient will add to the exposure. If theambient is notdark, the added light from the flash canoverexpose the subject. So, if the ambient light is fair orbright, and you for some reason do not want to use theTTL BL mode, you should reduce the flash power bysetting some negativeFOLC to avoid overexposure. Theamount to use is a judgement call, which is one of the

things that make using TTL flash in difficult in fair andbright light.

I consider the plain TTL mode to be a legacy mode thathas now been replaced by the much better TTL BL mode as Nikon's default flash mode, and tend not to useit much.

TTL BL

TheTTL BL mode is now Nikon'sdefault TTL mode when the camera is set to matrix orcentre weigthted metering. On the Speedlight SB-900,SB-800 and SB-600 you can still force plain TTL whenthe flash is mounted on the camera, but as soon as youmove the flash off-camera, it will automatically operate inTTL BL mode unless you select spot metering. If you areusing the Nikon SB-400, SB-700, or some third partydedicated flash, you do not have the option to use plainTTL if the camera is set to matrix or centre weigthtedmetering. Instead, the TTL BL mode is selected

automatically when the camera is set to matrix or centre



weigthted metering, and plain TTL mode is selectedautomatically when the camera is set to spot metering.

The TTL BL mode is the most complicated andsophisticated flash mode on the Nikon Speedlights. Ifyou try to read about the TTL BL mode in books and onInternet sites, you fill find a lot of different descriptions.Desmond Downs argues that most of these descriptionsare outdated. I think he is right. My description belowhas been revised after I read Downs'blogand reproducedhis tests. In these outdated descriptions, you may see

that the author refers to the TTL BL mode TTLBaLanced fill orTTL BackLit , and the idea that TTL BLshould be restricted to fill flash and/or backlit subjects.This is no longer the case. The re-engineered TTL BL isdesigned to be used both for flash key and flash fill.

The description of TTL BL that follows is based on

extensive experiments with both a Nikon D80 and aNikon D700, together with a Nikon SB-900 flash, in anattempt to determine what really goes on in the TTL BL mode. The findings are believed to be correct for theNikon D200 and newer bodies. Older Nikon DSLRs (i.e.D1, D1H, D1X, D2H, D2Hs, D2X, D2Xs and D100) useda separate,secondary metering system for TTL BL flash

exposure that worked differently. This old version of TTLBL is now mainly of historical interest and will not bedescribed here.

The TTL BL mode starts out by making two separateexposure measurements prior to the exposure. One is afocus-point and highlight biased measurement of thepre-flash reflected by the main subject, and one of the

ambient light lighting up the subject using the light



measurement mode (matrix or centre weighted) selectedfor the camera.

Since the TTL BL flash measurement is biased towardsthe active focus point, there is no need to use the FVlock when you're using the TTL BL mode, even if yoursubject is off-centre. Just make sure your subject is tiedto your main focus point.

In the TTL BL mode the camera computer may take thedistance to the in-focus subject (as reported by a G- or

D-type lens lens) into account when computing flashpower. (However, it only does if the flash is not bouncedand the focus distance is within flash range. If the flashis bounced or focus distance is outside the flash range, itdoes not use the distance data.) This means that if yourfocus is off, the camera may use the wrong distancedata and you will end up with a picture where your main

subject is out of focus and under- or overexposedbecause the flash fired with the wrong power setting.

Further, in TTL BL mode the camera's exposurecomputer tries to combine the measurement of thereflected pre-flash and the ambient. The intent is tooutput just enough power from the flash to make themain subject adequately lit. The flash power algorithm

seems to be exposing for the highlights. It seems muchless inclined to overexpose highlights than the algorithmused in TTL mode. I seldom find the need to usenegative FOLC in TTL BL mode.

To be able to use the flash in TTL BL mode, you mustuse 3D matrix metering (recommended) or centre-

weighted metering. Spot metering will force the camerato TTL.



For the most accurate results, the use of Nikon D- or G-type lenses is also recommended. The distanceinformation from the lens and 3D matrix metering is then

used in the computation to determine the amount offlash light to put out.

The computations involved in determining flash power inTTL BL mode are complex. In certain circumstancesunder- or overexposure may occur. To help youanticipate these circumstances, some of the situationswhere the TTL BL mode may not work well, are outlined

below:

• If the background is very dark (e.g. a stage withblack walls) or very light or reflective (e.g.: an icehockey match), then the complex automaticmeasurement and control system required to maybe fooled into under- or overexposure.

• If the composition have the main subject onlyoccupying a small part of the frame compared to the

overall field of view, the flash calculation may bebased upon the background. This may result in anerroneous flash power setting for getting a correctexposure of the main subject.

• When using a wide angle lens, dominant light

sources or highly reflective surfaces may affect theflash calculation and result in underexposure. Sinks(dark regions that do not reflect any light) may forthe same reason result in overexposure.

• If the camera is being used for longer times at ahigh frame rate the power drain on the batteries inthe flash system may become too great to supportthe sustained highly critical measurement thatTTLBL fill flash requires. In this case one shot out of a



sequence may be affected as the equipmentattempts to cope with falling flash battery voltageand high current demand.

In such situations, you will probably get better results ifyou use the plain TTL or non-TTL Auto mode. In somecases, you may need to take full control and switchtoManual mode.

Auto

The non-TTL Auto (A) and Auto Aperture modes found on some Nikon Speedlight and theAperture value (Av) mode on the Nissin Di866 are modesfor automatic flash exposure control that operates likethe classic “auto-thyristor”flashes from the 1970ies (e.g.the Vivitar 283 ).

In the auto modes, instead of measuring through thelens, a built-in sensor at the front of the flash measuresthe average flash light reflected by the entire scene anduse this to determine the output level of the flash. Themeasurement is usually done in real time during theactual exposure, and the flash is turned off by a thyristor

circuit within the flash when the sensor has determinedthat the scene is sufficiently lit.

The auto modes are not available on the SB-600 or SB-700. On the Nikon SB-800, there is no pre-flash in theAuto mode, but a pre-flash is used in Auto Aperture mode. On the Nikon SB-900, you can toggle pre-flash onand off in both auto modes. On the Nissin Di866



Aperture value mode) there is no pre-flash and you haveto enter both aperture and ISO “by hand”.

On Nikon Speedlights, ISO and focal length arecommunicated from body to flash in both Auto modes.The Auto Aperture also communicates the aperture,while in the the plain Auto mode, you must set theaperture on the flash “by hand”.This emulates the waythe original “auto-thyristor” flash units worked, andmeans that you can quickly dial in any amount of FOLCby “lying” to the flash about what aperture you use.

The pre-flash sequence that is intrinsic to the TTLmodes introduces a tiny shutter delay. Since the automodes let you control the flash in real time, you can usethe auto modes without a pre-flash and therefore withoutthis shutter delay. Since there is no pre-flash, the Automode is also handy when photographing people that

blink when exposed to the pre-flash.

Manual

Nikon offer three different manualmodes on some of its Speedlights: A vari-power Manual

(M) mode, stroboscopic repeating flash mode (RPT),and something called distance priority mode (GN).

When you set one of the manual modes, nothingmeasures the light. You control the power of the flash bysetting the desired power ratio (M) and (RPT), ordistance to the subject (GN), on the flash.



In vari-power Manual (M) mode, you control the outputpower of the flash by setting the desired power fractionfrom“1/1” to as low as “1/128”. Every time you half the

power setting, power is reduced by -1 EV (i.e. one f-stop). Most flash units let you adjust the power in stepsequal to 1/3 EV.

The power of the flash is actually determined by theduration of the burst of flash light. The less power youset, the shorter the duration is. The table below showsthe duration of flash as a fraction of a second for five

different flash units.

Power SB-600 SB-700 SB-800 SB-900 Di866

1/10

EV1/900 1/1042 1/1050 1/880 1/600

1/2-1

EV

1/1600 1/1136 1/1100 1/1100 1/900

1/4-2EV

1/3400 1/2857 1/2700 1/2550 1/1500

1/8-3EV

1/6600 1/5714 1/5900 1/5000 1/3200

1/16-4

EV

1/11100 1/10000 1/10900 1/10000 1/5000

1/32-5EV

1/20000 1/18182 1/17800 1/20000 1/9000

1/64-6EV

1/25000 1/25000 1/32300 1/35700 1/15000

1/128-7EV

- 1/40000 1/41600 1/38500 1/22000



This feature of manual flash is very useful forhigh speed flash photography . This is a technique very youphotograph fast moving objects (e.g. drops splashing

into water) and use short-duration flash to “freeze”movement. For typical drop splashes, a flash duration of1/20000 is suitable.

To minimise shutter delay, it is common to open theshutter before the action starts, and instead make theflash determine the instant of exposure. For this to work,you need the room to be so dark that the ambient does

not impact on exposure. For much more about this typeof photography, seehiviz.com.

Repeating flash (RPT) is a special manual mode wherethe flash fires repeatedly during a single exposure. Thismay be useful for a technique known as stroboscopic motion photography , where stroboscopic (i.e. pulsing or

repeating) light is used to capture multiple images ofcertain fast-moving bright objects set against a darkbackground on a single frame (e.g. abouncing golf ball).

When using repeating flash, you should use thefollowing formula to work out the shutter speed:

Shutter speed = Number of strobes / Frequency

For example, of you set up the Speedlight to fire 20strobes at 10 Hz, the shutter speed should be set to20/10 = 2 seconds.

You will lose power in the RPT mode. There is a table inthe flash's manual that will tell you how much you lose,depending upon the strobe frequency and the number of

strobes you want to fire. For example, a SB-900



Speedlight set up to fire 6 strobes at 6 HZ, will fire at 1/8of full power. With 24 strobes at 100 HZ, the flash willfire at 1/128 of full power. This means that with a single

Speedlight, repeating flash is only feasible to capturesmall objects at close range. You will need an industrialstroboscope for a full body shot (or a whole bunch ofSpeedlights firing in sequence).

Traditionally, repeating flash made it possible to makemultiple exposures at higher frame rates than continuousshooting with a DSLR. However, the continuous

shooting modes of some DSLRs offer much higherframe rates than the motor-drives of the film era, andhigh-speed video is also becoming more and moreavailable. These, and other advances in high speedphotography, is making repeating flash less important asa means of capturing fast movement.

Finally, the distance priority manual mode (GN) is amode where the flash controls the light output by takingthe distance you set at the back panel and translatingthat distance to a power setting by means of the flash'sguide number. If you don't understand what that means,don't worry. It is not a mode most people will find veryuseful. Only Nikon's top-of-the-line Speedlights offer this

mode.4. Understanding Flash Exposure

There is nothing that stops you from using flash in one ofyour camera's fully automatic exposure programs (greenAuto, or one of the vari-programs). If you do, the camerawill take care of setting the shutter speed and aperture

for you. If you also use one of the automatic modes on



the flash, you will not have to deal with setting exposureyourself. All you have to do is to frame and focus.

Fully automatic exposure settings do not give you muchcontrol over things. To pick these settings yourself, youneed to understand how your Speedlight interacts withthe camera's exposure settings (shutter speed, apertureand ISO) and also how the light from the flash interactswith the ambient light.

How all this come together is explained below:

Flash and Shutter Speed

If we consider a high-contrast scene were some partsare lit by bright sunlight, and other parts are in deepshadow, we'll find that while the sun will outshine theflash in the sunny spots, the light from the flash will havethe most impact in the shadows. Also, the output of a

camera-mounted Speedlight decreases in proportion tothe square of the distance. In other words, each doublingof distance will reduce the output to 1/4 (1/22).

This means that the flash will have the greatest impacton objects that are in the shadows and on objects thatare near the camera. Objects that are already brightly lit

by the ambient and objects that are further back (in thebackground) will receive much less impact from the flashand a greater proportion of their exposure will be causedby the ambient light.

Aperture and ISO works the same way with flash as theydo without. Shutter speed, however, works somewhatdifferent, so in the rest of this section, we shall focus on

shutter speed.



The duration of the flash blink is much shorter than anyshutter speed you can use. As a result, the shutterspeed does not influence the impact of the flash upon the

exposure. Instead the shutter speed determines theexposure for the parts of the scene were the flash lighthas the least impact (i.e. the highlights and thebackground).

The fact that the shutter speed does not impact on theflash's contribution to the exposure is the basis for a veryuseful technique known as “fill flash”. The main idea

behind this is to set a combination of shutter speed andflash output power where the light contributed by theflash only make a auxiliary impact on the scene, filling inthe shadows, but otherwise letting the scene be lit byambient light.

Unless the camera is used in Manual (M) or Shutter

priority (S) mode (where you pick the shutter speed), thecamera's built in light meter will try to set a shutter timethat will give you correct exposure for the ambient light.

However, when the camera senses a dedicatedSpeedlight in the hot-shoe, by default, the maximumshutter speed in the P and Aexposure modes arerestricted to 1/60 second or shorter for“safe” handheld

operation (you can change this limit in the camera'scustom settings if you think that your hands are moresteady than Nikon's engineers). You can override thisdefault by dialling in Slow-sync Flash .

Likewise, the maximum shutter speed that in the P andA exposure modes are restricted to the x-sync speed or

longer. You can override this by setting Auto FP .



By setting the shutter speed long enough, you may beable to capture enough of the ambient light to get theexposure right for fill flash. However, this may result in

shutter times unsuitable for moving subjects, or maymake it necessary to use a tripod.

Exposure compensation

If you are unsure about how flash light and ambient lightmixes, you can check the result by using the LCD screenon the camera for a review and to look at the histogram.

(If you're unfamiliar with histograms, see this note byRon Day:Interpreting & Using Histograms.)

If the histogram and/or review image on the camera'sLCD screen reveal a problem, such as clipped highlightsor blocked shadows, you may correct the problem byusing exposure compensation.

You may do this on the camera and flash. The former isreferred to as Exposure Value (EV) adjustment. Thelatter is known asFlash Output Level Compensation (FOLC). Use EV on the camera to modify the exposureof both the background and the output of the flash, andFOLC on the flash to modify the flash output level only.

Note that if your get underexposure because your flashis underpowered for the task at hand (e.g. your mainsubject is too far away, or you are trying to light thebackground on a huge, dark set with a singleSpeedlight), setting a positive FOLC will not have anyeffect. You instead need to bring a more powerful flashunit, open up the aperture, or increase the ISO.



To lighten the background only, set the camera'sexposure mode toS (shutter priority) or M (manual), andset the shutter speed to a long enough shutter speed to

give he background the right exposure without flash. Youmay have to set the camera's flash sync mode to slow sync and use a tripod to bring out background details insome low-light situations.

ISO

How auto ISO operates with flash depends on the

camera model.

In all Nikon DSLEs produced since 2009 (Nikon D300sand later), if you have auto ISO enabled, the camera willset the ISO based upon the ambient without taking intoaccount that flash will be used.

On some older models, having auto ISO enabled would

increase the ISO if the the pre-flash measurementindicated that the built-in or hot-shoe mounted flashwould be underpowered at the base ISO setting, withouttaking the ambient into account. In these models, autoISO would be disabled when you use AWL to control off-camera Speedlights.

To determine how your camera model works when autoISO is used with flash, with and without AWL, you maywant to experiment.

5. Read More

The article you are reading is part of a series aboutdedicated flash for Nikon cameras. Here is an overview

of the series:



• Introduction to Nikon's CLS – terminology andfeatures.

• Overview of Nikon Speedlight models compatible

with the CLS.• Basic settings for different ambient lighting

situations.• More settings and modes, both on the camera and

on the flash (this article).• Flash receipes for using a single on-camera

Speedlight.

8 responses:

2 SB600s or 1 SB900?From: Raphael F. — 2010-06-11 13:58I have a D80 with an SB800. I have the budget to buyeither a SB900 or 2 SB600s. The main lens that I use isan 18–200 mm VRII Nikkor lens.

Since I have the D80 (recently upgraded from a D70s), I

can use both the SB900 and SB800 for portrait pictures.But if I had the 2 SB600s I could have a bit more fun.

On the other hand, I'm concerned that the SB600 won'tbe powerful enough, particularly as I want to do familyportraits in the main as well as parties.

Meaning of abbreviation FP as in Auto FP. Not Focal

Plane.



From: Tom R. — 2010-07-27 19:07FP does not mean focal plane. This is after all a flashterm. It is Nikon's term for high speed flash sync. Nikon

calls it Flash Pulse to be different from Canon, and it isabbreviated as FP. This is actually what happens with allhigh speed flash sync. systems. The flash fires very fastover and over at low power to give the affect of a longerflash duration.

From: gisle — 2010-07-28 07:22

@Tom Reynolds,where in its literature does Nikon expand “FP” to “FlashPulse”?

It is not a Nikon term. In the beginning, the term wasused by both Canon and Nikon to refer to an electronicflash mode capable of syncing focal plane shutters athigh speed. It was probably called “FP-mode” because itimitated so-called “FP-bulbs”. These were special flashbulbs designed to solve the problem that ordinary flashbulbs had syncing with focal plane shutters. Centralshutters did not have this problem. Later, Canon

replaced the term “FP” with “HSS” (High Speed Sync) intheir vocabulary, while Nikon retained “FP”.

Respected author NK Guy tells about the origin of theterm “FP” here.



The 'New' TTL-BLFrom: Desmond — 2010-08-11 10:56

I've done my own studies on Nikon's TTL-BL system anddisagree with a few statements.

TTL-BL does not meter very strongly for the centre of theframe - it does restrict its metering to the focus pointdiamond but can meter off the side focus pointsregardless of the centre of the frame when appropriatewhile TTL averages out the centre of the frame as you

say.

The new TTL-BL has nothing to do with 'back-lit', itsimply exposes for the best lighting of the subject whiletaking the ambient ['background'] exposure into accountas determined by the metering mode you have selected.

Hope this helps …

http://desmond-downs.blogspot.com/2010/07/flash-nikons-new-ttl-bl.html.

From: gisle — 2010-08-26 03:16

@Desmond,thanks for the link.

I've duplicated your tests and I agree with your findings.As I result, I've changed the article to reflect this newinsight. Hope you are more happy with the revisedversion.



Slight changes to theoryFrom: Desmond — 2010-09-12 07:16

Looking good :).I've been in contact with one of the original designers ofthe TTL-BL system since my blog created a bit ofcontroversy and many originally argued with my testresults – until they acknowledged that Nikon had in fact

changed the information the camera sends the flash – this was confirmed by a technician. The one point I'veadjusted in my blog is subtle but important. TTL-BLdoesn't actually use the individual focus points but ratherthe “focus point diamond”, basically the pattern matrixmetering uses. It can select the area it needs to meteroff within this pattern of focus points.

I'll just add that I created some more controversy bydoing some studies of fp flash mode http://desmond-downs.blogspot.com/2010/09/auto-fp-flash.html whichproves that some cameras lose more power than others,depending on the speed the shutter travels – and thehigher shutter speeds are in fact better when in fp mode.:)

FLASH MODEFrom: Ernest — 2013-07-18 19:22

Dear Sir,I am using Nikon SB 900. I found out a mode whereby I



can set either "Flash or modelling" in the setting. Canyou advice me what are the differences of these twosettings? Best regards, and thank you.

Nikon SB-900 modelling light settingFrom: Gisle H. — 2013-07-19 13:21This setting changes the operation of the flash triggerbutton. When set to "Modelling", pressing the flash

trigger button (illuminated button above the powerswitch) will pulse a modelling light so that you can seehow the light from the flash will effect your subject(shadows, etc). I.e.: it gives you a brief preview of howyour light is going to fall.

When set to "Flash", pressing the flash trigger button will

fire a single flash

nikon flash use

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