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Fill Flash
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Ryan, 14 March 2010

Ryan on the See-Saw, 14 March 2010. bigger. Fill-flash lit the shadows on his face, otherwise, they would have been black. (Nikon D40, Nikon AF-S NIKKOR 35mm f/1.8 G , Nikon SB-400 flash with velcroed-on 1/2 CTO warming gel. Overall exposure compensation set to my personal default of -0.7, and flash exposure at 0.0)

This free website's biggest source of support is when you use any of these links when you get anything, regardless of the country in which you live. Thank you! Ken.


September 2012; April, June 2010   Better Pictures   Nikon   Canon    All Reviews

Better Pictures:   The Secret   Composition   Simplicity

FART   Shadows   Lighting   Adjustments   Acquisition   Carry Less

It's Not Your Camera   Exposure   WB   Don't Worry: Shoot


Fill-flash is using your flash to fill-in darker parts of a picture already lit by other light. I use it for almost all my people photos outdoors.

Adding fill flash is easy: just turn on your camera's flash, and almost all cameras today automatically give the results I'm showing here. You don't need to fiddle with any settings; just press the Flash (bolt) button and your camera does the rest — but no camera pops up the flash by itself, so you have to turn it on by yourself and the camera does the rest.

Indoors, fill-flash lets you see people's faces better, and lets you light up an interior and see out the window better than HDR.

Outdoors, fill flash lights-up faces so they aren't drowned in shadows.

Fill flash puts highlights in people's eyes so they look alive.

Fill flash lightens shadows and adds detail to darker areas, while preserving highlights.

I always use fill-flash in direct sunlight.

The beauty with Nikon is that fill flash is so easy, they forgot to explain it in the manual: just turn on your flash!

Ryan off to school

Ryan off to school, with fill-flash 28 September 2012. (Nikon D600, Nikon 28-300mm VR at 70mm, f/8 at 1/200 at Auto ISO 100, AUTO WB A4 M1, STANDARD Picture Control with +1 Saturation, 6 sharpening. SB-400 for fill-flash, no dodging needed.) bigger.


Ryan off to school

No fill-flash.(Nikon D600, Nikon 28-300mm VR at 70mm, f/9 at 1/200 at Auto ISO 100, AUTO WB A4 M1, STANDARD Picture Control with +1 Saturation, 6 sharpening. No fill flash and thus required heavy, sloppy dodging.)


Ryan off to school

Same no fill-flash shot, dodged (lightened) in Photoshop CS6. Still looks awful technically! bigger.


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Ryan with fill, 13 June 2010

Ryan in backlight with fill-flash. Looks natural.


no fill

With no flash.


How-to       top

All you do is turn on the flash and shoot. Everything is automatic, and very, very smart.

In the old days you had to be very skilled at Algebra to do all the calculations of distances, ambient light and guide numbers, but today on Nikon, just pop up the flash and go.

Canon does the same thing, but Canon's flash control system is nowhere near as good as Nikon's. Actually, no one's flash exposure control system is as good as Nikon's. Canon's cameras try, but Canon users often have to adjust flash levels, while Leica and Contax users are still pretty much where they were 30 years ago. I'll cover them, and fill on all old cameras, later.

On my Nikons, I use Professional mode, the "P" setting, so the flash only goes on or off as I tell it. Other modes work, too, but you might have the camera forcing the flash on or off by itself, or have the camera run out of shutter and aperture options. In Pro (P) mode, the camera does whatever it needs to to give the best shot it can.

Most Nikons since the 1990s have done this more or less perfectly, and today's DSLRs are even better.


Katie with fill, 11 May 2010

Katie, with fill-flash: looks natural. (Maui, 11 May 2010 for details)


Katie, no flash, 11 May 2010

Katie, no flash: Looks crappy. (Maui, 11 May 2010 for details)


Which Flash?       top

You can use the built-in pop-up, or I prefer the SB-400 on my DSLRs and iTTL F6.

The only thing the SB-400 does better than the pop-up for fill is that it has a little more distance range, and recharges itself almost instantly for each shot.

There's usually no need for a bigger flash like an SB-600. All a bigger flash does is have more maximum firepower, but not by much.

The flash exposure is controlled by the camera, and only fires as much light as it needs for each shot. The SB-600 and SB-900 can throw out more light than the SB-400, but only if it's needed. You only need this extra power reserve if you're shooting at longer distances, or in very bright light, or on a camera with a slower sync speed like 1/180.

If you're shooting weddings for a living, of course get the bigger flash. You're using it all day.

If you're like me and are carrying the camera all day and only pulling it out when the kids do something cute, then I prefer the smaller flash.

Sunset, Cambria,

Sunset, Cambria, 18 September 2004. enlarge. The flash lit the rocks in the foreground, which otherwise would have just been blackness. (Nikon D70, built-in flash, slow sync, f/8 at 1/30, shade WB, 12-24mm AF-S.)


Abbott's Lagoon, Point Reyes, 01 September 2009. roll mouse-over to compare without flash. bigger.

Fill-flash also works wonders with pocket cameras. I made this shot of the lagoon with a tiny Canon SD980 point-and-shoot, using only its built-in flash. By using the flash, it let me expose for the sky, and get detail in the foreground. Without flash, it looked awful.

Daylight fill-flash doesn't often work well on pocket cameras. By "not work well," I mean that it often will require too much fiddling with settings that have little effect. SLRs do this much faster, easier and better.


Flash Power & Sync Speed       top

You can tell if you ran out of power with any of these flashes: the little bolt in the finder flashes angrily for a few seconds after the shot, and then the flash takes several seconds to recharge before the bolt comes back on solid.

This is where fast sync speeds, like the 1/500 of Nikon's older DSLRs, come in handy. Faster sync speeds give a flash more effective power.

You need not worry about sync speed when shooting. Your camera automatically uses whatever speeds it can. Once you've chosen your camera, you can skip the rest of this section; you've got whatever you've got.

For every stop by which your maximum sync speed increases, you get one more effective f/stop of maximum available flash power.

This is because the flash's contribution to exposure does not vary with shutter speed (the camera sees everything from the instantaneous pop), while ambient exposure is affected by shutter speed. At faster shutter speeds, the aperture has to open to get the same background exposure, which lets in more light from the flash.

With a one-stop faster sync speed, the camera tells the flash to use only half as much power, since the aperture is open one more stop than it would be at a slower shutter speed. Therefore, in bright light with a 1/500 sync speed, each shot uses only half the flash power, which gives you twice the effective battery life, and half the recycling time than with cameras with 1/250 sync. This gives your flash twice the effective maximum power if it needs it, and also lets you use larger apertures in daylight to throw backgrounds out of focus, and lets you stop action.

With a given amount of flash power, sync speed alone determines the ratio between flash fill and ambient light. ISO and aperture only control the overall exposure. Since shots in daylight are shot at lower ISOs and middle to small apertures, choice of ISO or lens speed is irrelevant, but your camera's maximum sync speed is often critical to being able to get enough flash power to compete with direct sunlight.

Fill flash is very important in daylight, and thus maximum sync speed is crucial. This is why pros have always considered sync speed one of the most important camera specifications.

This is also why I love my D40 and its 1/500 sync so much: it lets me use the tiny SB-400 flash instead of needing something bigger to do the same thing. With today's DSLRs and their slower 1/250 sync, you might need the greater power of the SB-600.


Color       top

I often attach a slightly-orange piece of plastic film (a 1/4 CTO gel) over my flash to make it look warmer. Shot as-is, flash usually looks too cool (blue) for me. Shot with a clight warming gel, it looks perfect like this:

Katie with fill, 11 May 2010

Katie! (Maui, 11 May 2010: Canon 5D Mark II, Auto ISO 400 (flash), Canon 50mm f/1.8, Professional exposure (P) mode chose f/7.1 at 1/200, Canon 220EX flash on-camera with 1/4 CTO warming gel.)


Here's a pro trick that even most pros don't know: you must match the color of the fill flash to the ambient light.

In daylight, it's no big deal, since flash is only a little bluer than daylight. I still usually use a 1/2 CTO or 1/4 CTO gel.

Gelled SB-400

Gelled SB-400. enlarge.

To use a gel, you buy a gel (an $8 sheet of plastic film), cut out a small piece, and tape it over your flash. I use adhesive-backed Velcro to attach it to my flash so I can take it on and off easily, and swap it with different filters. As shown, I have two filters always with my flash, which I easily can use or stow.

At sunset, using fill to light your subjects backlit against the sunset, flash is much bluer than the orange sunset. Too many people make the big mistake of using unfiltered flash at sunset, giving ghastly blue or purple people against a pretty sunset. At sunset, you must use a warming gel to make the flash more orange, otherwise, your subjects will be filled with what looks like bluer light.

Indoors, you must get the flash to match the indoor lighting. Otherwise, the people will look blue, or most often, the people look OK but the background goes orange.

Indoors under tungsten light, use a Full CTO gel to make your flash match the tungsten lights. Now set your camera to tungsten white balance, and voilà!, everything looks perfect. This shot was made this way:

Rockwell at Red Ball

Rockwell at Sushi's "Red Ball" art auction. evil twin. Shot on a D1H, Full CTO gel over flash, tungsten WB, gallery lit by a zillion MR16 halogen track lights, ISO 800, 1/20 at f/4.5, aperture-priority auto, Nikon 24-85mm AF-S.


Flash and Background Brightness       top

Flash brightness

If you want more or less of a fill effect, you change that by changing what Nikon calls "Flash Exposure Compensation." That the +/- symbol with the bolt next to it.

Even Nikon's cheapest cameras like the D40 can adjust this. Depending on your camera, hold the bolt button (often by the flash), and hold the +/- button, often by the shutter release.

As you're holding both buttons (sorry), spin the rear dial, and you'll see + or - numbers in your finder.

+ makes the flash brighter, and - makes it darker for the next shot. Make a shot, and adjust to taste for the next shot.


Background brightness

Flash pictures taken indoors usually have black backgrounds. This is because it's dark indoors, much darker than the flash.

As we learned above, the shutter speed adjusts the ambient background brightness, with no direct effect on the flash.

To lighten backgrounds indoors, use longer shutter speeds.

Since your camera chooses all this automatically, how do we get it to use slower speeds?

By default, the NORMAL flash sync setting on your camera prevents the camera from using any speed slower than about 1/60. It does this so pictures don't get blurry from motion, but it also means backgrounds go black indoors.

To lighten backgrounds indoors, set SLOW sync, which is usually set by holding the flash bolt button and spinning the rear dial until SLOW shows on your top or rear LCD (see your manual).

In SLOW sync mode, the camera is free to use slower shutter speeds to expose the background properly.

The problem in very low light is that shutter speeds can get very long, leading to blurs. In these cases, you'll have to set the ISO to a higher speed, or fix the longest shutter speed to something reasonable. Try 1/8 second.

To prevent the shutter speed from getting too long, many cameras (Nikon, Canon, LEICA M9, etc.) allow setting of the slowest sync speed in a menu. When you do this, everything is still automatic: the camera sets everything automatically as the light changes, paying attention to your preferences.

Of course you always can force the camera into manual exposure to lock the shutter speed, or use the shutter-priority (S or Tv) mode, but if you know all this, you probably wouldn't be reading this article.

Personally, I'll set the slowest sync speed to about 1/8 and shoot away in program. In this way, I'm set for everything from daylight to indoors.


ISO Settings       top

I use AUTO ISO all the time. The only catch is that as soon as you turn on a flash, ISO stays at its minimum.

This is great for daylight, but to lighten backgrounds indoors, you'll need to set a higher manual ISO so your shutter speeds can remain reasonable.

In the shot of me indoors, I set ISO 800 so that the shutter speed was around 1/20. This exposed the background well, and the flash lit me well, too. With the old flash I used and the D1H, the white of my shirt is a little too light, but hey, I handed my camera to a drunk to take my picture. Today this wouldn't be a problem with modern camera's highlight control and newer flashes like the SB-400.

Notice how the shot of me required 1/20 at ISO 800 to get a decent background, and this was a very well lit gallery. In darker locations, it's tougher to get backgrounds to look light enough without either blowing out the flash at crazy-high ISOs, or having to use very long shutter speeds.

Today we can use insane ISOs to handle very low light, but the camera may not be able to dim the flash enough to let it match the low ambient light. Flashes can only vary their outputs over a limited number of f/stops.

If this is a problem, you can use a darker gel (called ND, or neutral-density) to darken the flash. The problem is that flashes can vary their power over several f/stops, but they can't always get as dim as needed to balance indoors in very dim light. In this case, something like an Full CTO + ND 0.6 gel balances the flash to match tungsten light indoors, and lowers its output by two stops. I'd only go this far if I was shooting at ISO 1,600 or higher.


Simpler Cameras       top

With old manual cameras, the Mamiya 6 and 7, or modern cameras frozen in in the 1950s like LEICA, fill flash is also easy.

Fill flash was a royal pain with manual flashes. You had to do five minutes of math for each shot. We won't do that.

Use an automatic flash and this becomes easy. By automatic, I mean a flash that has its own independent automatic function. These flashes have an "A" setting, or a few settings where you can select among several different apertures. These flashes have been around since the 1970s and you can find them used for a few dollars anywhere.

Use any old or new automatic flash, like a 1970s Vivitar 283, 1990s LEICA CF, 1980s Nikon SB-20 or today's SB-900. It doesn't matter, but avoid using a flash dedicated to a different brand of camera, and avoid using very old (1960s or 1970s) electronic flashes on modern electronic cameras. Otherwise, no problem.

Once you've got your flash and chosen the aperture you want to use, simply set the flash's automatic adjustment for an f/stop one-stop smaller than your lens setting. Be sure to set your ASA or ISO on the flash before looking at its settings.

In other words, if you set your camera to f/8, select the setting on the flash that expects you to use f/5.6.

This makes the flash put out less light than needed to expose the image fully, which turns out to be exactly the right amount of light needed to fill shadows.


With older automatic cameras, or today's LEICA or Mamiya etc., choose your automatic aperture on the camera, and set the flash for one-stop wider. Now you'll get fully automatic exposure and fully automatic fill-flash. Wow!

If lens is set to
then set flash for

If you want more or less fill, simply change the setting on the lens or on the flash.


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Thanks for reading!



Mr. & Mrs. Ken Rockwell, Ryan and Katie.


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