Help with flash photography

HarveyMushman · January 28, 2008

Flash photography confuses me, and I’d like to develop some proficiency in a directed manner, not via trial-and-error like I am now.

I have a SB-600 Speedlight and have become reasonably adept at bouncing the light off the ceiling or walls. I do this when A) I’m indoors and

the flash is the primary light source. I’ve even experimented with tungsten filters to get a natural look when incandescent lights are in the frame.

What I’m having a real hard time with is fill lighting, using the flash to fill in some shadows while exposing mainly with ambient light. In low-light situations—when the necessary shutter speed is well below the camera’s max flash synch speed (1/250)—I don’t have too much difficulty.

Example (D300, manual exposure of ambient light with a -3.0EV fill-flash from the pop-up speedlight):

But when the ambient light is plentiful—mid-day for example—and the required shutter speed is likely to be faster than 1/250, I have a hard time avoiding overexposure when trying to fill in shadows with the flash. I also have a hard time bypassing the camera’s automated flash-exposure settings, even in manual. I must be missing something very basic here. :scratch

Can anyone recommend a good flash photography resource or tutorial, either online or in the form of a book?

I don't want to rely on Program Auto mode!

Cuong · January 28, 2008

Try this from the Strobist: http://strobist.blogspot.com/2006/03/lighting-101-balancing-flash-and.html

Cuong

HarveyMushman · January 28, 2008

yukio wrote:

Try this from the Strobist: http://strobist.blogspot.com/2006/03/lighting-101-balancing-flash-and.html

Cuong

That's a good start, thanks.

Scott_Quier · January 28, 2008

I shoot Canon, so I've relatively ignorant of Nikon features. Does you camera support high-speed shutter synchronization? If so, you're in like Flyn. Determine your exposure for the ambient lit areas, set your flash for approx 2/3 to 1 stop less. Done.

HarveyMushman · January 28, 2008

Scott_Quier wrote:

I shoot Canon, so I've relatively ignorant of Nikon features. Does you camera support high-speed shutter synchronization? If so, you're in like Flyn. Determine your exposure for the ambient lit areas, set your flash for approx 2/3 to 1 stop less. Done.

It does, but the fastest synch speed is 1/250, which is plenty indoors but when outside in daylight it's not enough. At least I think it's not enough, given I've only started the learning curve. My old D70 allows 1/500, which I'm learning is a valuable feature.

jfriend · January 28, 2008

HarveyMushman wrote:

What I’m having a real hard time with is fill lighting, using the flash to fill in some shadows while exposing mainly with ambient light.

But when the ambient light is plentiful—mid-day for example—and the required shutter speed is likely to be faster than 1/250, I have a hard time avoiding overexposure when trying to fill in shadows with the flash. I also have a hard time bypassing the camera’s automated flash-exposure settings, even in manual. I must be missing something very basic here.

Here's what I do with my D2Xs and SB-800 (same thing should work for your setup) for outdoors fill flash.

If I can't bounce and I don't need max power from the flash, I always try to use a diffuser dome on the flash. No matter what your subject is, that will always create a more pleasing flash lighting than direct flash because it creates a larger apparent light source which dulls shadows and helps reduce hot spots. I use the dome that came with the SB-800. You can buy an aftermarket dome or a Nikon dome for your SB-600.
When shooting outdoors, you have to be aware of the shutter speed since you can't do a full-flash sync at over 1/250th. If, because it's so bright, you need a shutter spped >1/250th, you either have to stop down to get your shutter speed below 1/250th or you have to use FP high-speed sync. This is available on the D300 and you must enable automatic use of it in your menus for it to be used automatically when it's needed. With it enabled, when the shutter speed is greater than 1/250th, it will automatically change the mode of the flash so that it fires several partial power bursts instead of just one burst. These partial power bursts can work at greater than 1/250th shutter speed. The only disadvantage is that you only get fractional flash power on each burst. Since you usually aren't using full flash power for fill-flash anyway, this is usually OK (unless your subject is a long ways away)
I always use some negative EV on the flash unit itself when using it for fill flash. It seems to depend a little on the situation, but I often use -2/3EV or even -1EV on the flash. This also keeps it from overpowering the scene.
Make sure your flash is set to TTL-BL so that the camera is still trying to expose properly for the scene.
Make sure you are not in spot metering mode because the camera won't operate in TTL-BL in spot metering mode.
Make sure your metering mode and regular camera EV is set properly so it won't overexpose the scene even if you didn't have flash.

I hope this is helpful.

Here's are a couple fill-flash shots I took recently. The first is a mix of full sun and shadows where the shot without fill is a disaster because of the shadows. The second is a dreary overcast day (it was snowing minutes before this) where the shot without fill has no contrast and drab colors:

Scott_Quier · January 29, 2008

HarveyMushman wrote:

It does, but the fastest synch speed is 1/250, which is plenty indoors but when outside in daylight it's not enough. At least I think it's not enough, given I've only started the learning curve. My old D70 allows 1/500, which I'm learning is a valuable feature.

I think we are not communicating. By way of example, high-speed shutter synchronization is a technology offered by Canon. Under normal circumstances, the fasted shutter synchronization is 1/250. But, with a flash that talks to the camera, it is possible to have a shutter speed of 1/2000 or more. What happens is that the flash pulses multiple times during the exposure so that all portions of the sensor are exposed. That's the up-side. The down-side is that each pulse is significantly lower powered than a single pulse (I guess that only makes sense).

So, if the fasted shutter speed at which you camera will synchronize with the flash is, as you say, 1/250 then I'm guessing you don't have the high-speed shutter synchronization.

HarveyMushman · January 29, 2008

John & Scott, thanks. I may have to open the D300's manual.

pathfinder · January 29, 2008

Is it the camera or the flash that determines the presence of focal plane shutter flash sync?

I am pretty sure the SB-800 does it, but not sure about the SB-600, since I don't shoot Nikon presently. I am certain the D300 is capable of FP synch, if the flash is capable. Camera bodies were capable of FP synch with flashbulbs 50 years ago, including Nikon.

Scott_Quier · January 29, 2008

pathfinder wrote:

Is it the camera or the flash that determines the presence of focal plane shutter flash sync?

I am pretty sure the SB-800 does it, but not sure about the SB-600, since I don't shoot Nikon presently. I am certain the D300 is capable of FP synch, if the flash is capable. Camera bodies were capable of FP synch with flashbulbs 50 years ago, including Nikon.

Unless I'm hugely mistaken (and that's happened more times than not

), HSS requires that both the camera and the flash support it (at lease in the Canon world). The following is my understanding, based on the reading and test/experimentation I've done, of how the flash and camera work together.

The flash duration is very, very short, measured in milliseconds.

The sequence of events when you are shooting at anything less than or equal to the flash synchronization speed of the camera is:

The first shutter curtain opens, exposing the entire sensor.
The flash fires
The second shutter curtain closes, ending the exposure.

Here's what happens during HSS:

The first shutter curtain moves, starting the exposure.
The flash fires, but this happens before the first curtain has completed it's travels so only a small portion of the sensor has been exposed to the light of the flash.
The first curtain moves a bit more.
The second curtain moves to cover the portion of the sensor that has just been exposed to the flash.
The flash fires again to expose the newly uncovered portion of the sensor.
The cycle repeats until the second curtain has completed it's travels.

The amount of the sensor exposed during each pop (and the number of times the flash must pop) has got to be a function of the size of the sensor, the speed of shutter curtains, and the duration of exposure (1/200, 1/1000, etc). As you can see, this is a quite sophisticated operation, requiring extensive communication between the camera and flash - and they both have to be able to speak the same "language" to get the job accomplished.

The up-side of this technology is that you can use flash as fill in very bright environments, even with shutter speeds in excess of the flash synchronization speed. The down-side is that the power of the flash is greatly diminished because it's popping a number of times for each exposure.

Looking back 50 years ago (I'm guessing here as I was not even a gleam in my father's eye then nor have I ever used such equipment - but would love to just for the experience), bulbs may have burned quite a bit longer and produced a more or less consistent amount of light during the entire burn. If that's the case, then I can see where a faster shutter speed might be quite possible - the bulb was burning for the entire duration of the exposure.

jfriend · January 29, 2008

pathfinder wrote:

Is it the camera or the flash that determines the presence of focal plane shutter flash sync?

I am pretty sure the SB-800 does it, but not sure about the SB-600, since I don't shoot Nikon presently. I am certain the D300 is capable of FP synch, if the flash is capable. Camera bodies were capable of FP synch with flashbulbs 50 years ago, including Nikon.

The SB-800 and SB-600 both support auto focal place high-speed sync. I don't see it listed anywhere in the SB-400 specs so it probably doesn't.

HarveyMushman · January 29, 2008

HarveyMushman wrote:

I may have to open the D300's manual.

There is indeed an Auto FP high-speed sync setting. With the built-in pop-up flash it's 1/320, which I now remember seeing in the camera's flash settings menu. But with an accessory flash like my SB-600 the number is whatever I want it to be, up to the max shutter speed of the camera (1/8,000). Cool. I'll go experiment tomorrow.

jfriend · January 29, 2008

HarveyMushman wrote:

There is indeed an Auto FP high-speed sync setting. With the built-in pop-up flash it's 1/320, which I now remember seeing in the camera's flash settings menu. But with an accessory flash like my SB-600 the number is whatever I want it to be, up to the max shutter speed of the camera (1/8,000). Cool. I'll go experiment tomorrow.

The faster your shutter speed goes, the more pulses the flash has to fire in order to cover the whole sensor (above 1/250th it's a moving slit going across the frame and the multiple pulses cover the whole frame as the slit moves across). The more pulses it has to fire, the less power it can put into each pulse, so you still don't want to crank the shutter speed up too fast or your effective flash power will be reduced more than you'd like. But, it can certainly go much higher than the native flash sync speed and that can be really useful in bright light.

Help with flash photography

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