# Using a speedlight and in camera metering...



## daimbert (Jan 22, 2014)

Very new to photography. Recently brought a Nikon d5200 and was not to happy with my photos, which are done primarily in doors. People suggested I get a speedlight first over a new lens (which I brought anyway 35mm prime). I got lucky and brought a Nikon Sb700 at a very very good price. Wow what a change in the quality of the photos.

The one question I have, which I hope someone can help with, is when using the SB700 with TLL do I ignore the light meter of the camera? Or do I still try to adjust exposure using the in camera light meter and meter to center? The reason I ask, is often times the light meter is saying I am two stops of light underexposed, I take a picture with the flash and it comes out very good. Does the pre-flash from the actual flash unit know that I am underexposed and compensates? Want to ensure I get good exposer as much as possible. 

Thanks

John


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## cynicaster (Jan 22, 2014)

Be careful on how you interpret the information you're seeing.  

There are actually two exposures at play when you use a flash: the "ambient exposure" and the "flash exposure", and the camera considers them separately.  In the generic case, the latter refers to the exposure of a foreground subject that is illuminated by the flash, whereas the former refers to the exposure of "the background", which is not affected so much (if at all) by the flash.  

I'm assuming Nikon handles this the same way as Canon, and if so, the reading you see on the exposure meter refers to the ambient exposure only, meaning that is the exposure you'd get with no flash at all.  This would make sense based on what you said about the meter reading 2 stops underexposed but the photos looking good with the flash firing.


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## KmH (Jan 22, 2014)

The in the camera light meter cannot meter the flash in a way that you can see. The duration of the flash is to short.
A hand held flash meter 'holds' the exposure (amount of light) it saw when the flash fired. The in camera light meter can't do that.

To some degree it also depends on which SB-700 TTL mode you are using.


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## TCampbell (Jan 22, 2014)

It turns you actually probably WANT the camera to "meter" for the available light and not the flash.  The Nikon iTTL metering system will take care of the flash on it's own -- by using pre-flash to determine how much actual flash should be used for your given camera ISO and aperture (but NOT shutter speed -- that part is mostly irrelevant when using flash because even with long exposure times, the flash is only illuminated for a very brief moment.)

By allowing the camera to meter for available light, it helps fill in the background in dark situations.

In bright situations, you want the flash to compete with the daylight backgrounds... e.g. if your subject is standing under the shade of a dense tree, but the background is in full sunlight, a proper exposure for the subject will leave you with a blown out over-exposed background.  By metering for the background and use flash, you can brighten up the subject to something that works with the scene.  Since they are supposed to look like they are in shade you don't want to exactly match the background... but coming with in about 1/2 to 1/3 of a stop would give a nice balance.


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## hirejn (Jan 24, 2014)

The TTL flash will illuminate the subject automatically until it reaches 18% gray reflectivity. So it doesn't matter whether the background is dark or bright, or what the camera says. In fact, nothing you change will affect TTL flash exposure except flash exposure compensation (FEC), or exceeding the limits of the flash. You could be in a programmed mode or manual, change shutter speed or aperture, and TTL flash will expose the subject the same. If you go to manual mode on the camera and set the exposure for -2 stops under correct, the scene may be underexposed but the flash will still illuminate the subject the same. That's because TTL flash is automatically going for one result every time -- 18% gray -- and flash exposure is separate from ambient exposure (big topic).

If you use the exposure compensation dial on the camera, you're adjusting the whole exposure, ambient plus flash. To change flash only, you need to use FEC on the flash. On pro bodies, switching to manual exposure disconnects the flash + ambient compensation so using exposure compensation on the camera affects only ambient, not flash. Not sure if that's true for entry-level bodies.

If you want to know how TTL works, I suggest reading this.


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## sk66 (Jan 24, 2014)

daimbert said:


> The one question I have, which I hope someone can help with, is when using the SB700 with TLL do I ignore the light meter of the camera? Or do I still try to adjust exposure using the in camera light meter and meter to center?



Depends on your goal. The meter is only telling you what the exposure will be for areas of the image that do not receive any flash. The flash exposure will always be "right" in TTL so you *can* ignore the meter.


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## Robin Usagani (Jan 24, 2014)

You want to ignore it.  But the farther away you are from your "correct" exposure, the harder the flash will work and the less ambient light you will see on your photo.  So if you are way underexposed, your ttl will probably fire almost 100%power.  You will run out battery in a few minutes.


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## WayneF (Jan 31, 2014)

daimbert said:


> The one question I have, which I hope someone can help with, is when using the SB700 with TLL do I ignore the light meter of the camera? Or do I still try to adjust exposure using the in camera light meter and meter to center? The reason I ask, is often times the light meter is saying I am two stops of light underexposed, I take a picture with the flash and it comes out very good. Does the pre-flash from the actual flash unit know that I am underexposed and compensates? Want to ensure I get good exposer as much as possible.



For flash indoors, typically you ignore the camera light meter. It reads the ambient light, not the flash. The flash system has its own meter, which is invisible to us.
The TTL flash is automatic, adjusting its own power level for the camera settings it discovers in effect (ISO and aperture).  Yes, the camera meter will show rather extreme underexposure indoors, simply because this dim light is where we need flash instead.

Outdoors, like in sunlight, you do want the meter to adjust for the ambient light (hard to ignore sunlight).   The flash is still automatic, but in bright ambient, the SB-700 automatically becomes fill flash (as opposed to main flash) in that situation, to prevent overexposing the subject in ambient.

There are more words involved in explaining that fully, but you might see Four Flash Photography Basics we must know - Flash pictures are Double Exposures


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