Fill Flash

[jecaph]

Since I am still kind of new to photography, I have a question about "fill flash." What exactly is it? Maybe someone can explain it for me, please.


Andrew

[Wil_Bloodworth]

Andrew,

"Fill flash" is where you use a flash to fill in where there are shadows... like when a person is standing with the sun on one side of their face or slightly to the rear... or something. Shadows would be under their neck or the other side of their face. You can use a flash to "fill in" where there's a lack of light.

This is not a very good explaination... but I'm sure someone else with a better one will chime in.

- Wil

[jeffkohn]

Fill flash just means that flash is not the primary lightsource for the exposure. In other words, most of the light is coming from "natural" sources such as the sun, or other ambient lighting, and you're just using the flash to "fill in" the shadows somewhat or boost the lighting in a particular area of the scene.

[jecaph]

You've guys have answered it perfectly. So, I am assuming that fill flash is used mostly for close ups, people and portraits?

[JohnRushing]

I'm not sure if it fits in the official definition but I always considered some of the lights in the studio as fill. There's the Main or key light and then the fill along with background light, hair light and so on. Just like your saying with the natural light fill light in the studion would be used to lighten or modify the shadows caused by the main or key light. I guess if your using hot lights it wouldn't be called fill flash but when your using strobes it would be. Either way the fill does the same job.

[Wil_Bloodworth]

Fill light is used in many many situations... but the most common examples are the ones mentioned above. A lot of times photogs will use it to give "pop" or artificial "sharpness" to foliage in trees or the like. There are many applications... you just have to decide if it is needed or warranted for the situation you're in... it is definetly a creative tool at your exposure (pun intended).

- Wil

[bfphoto]

Also, fill flash is used to set the ratio in a photography. If I remember correctly, the ratio in film portraits is somewhere around 3 to 1, ie., key light f 11 and fill light f 5.6 and one half. For digital, I have heard that a 2 to 1 is better because digital is more contrasy than film. In this case, try f 11 for key and f 8 for fill. Actually, it is a matter of taste. Try different ratios and see what you like. Actually, I may have it backwards, you may use the key light to set the ratio, but you get the idea.

[mwaldrop]

Okay, another newbie question related. What is the "key light" and "fill Light" ratios in bfphoto's post? Is there a technical article to be read related to these ratios and their purposes? Or can someone give us a simple explanation? I understand fill flash concepts but the ratios are new. Thanks

[bondarnes]

Originally Posted by mwaldrop

Okay, another newbie question related. What is the "key light" and "fill Light" ratios in bfphoto's post? Is there a technical article to be read related to these ratios and their purposes? Or can someone give us a simple explanation? I understand fill flash concepts but the ratios are new. Thanks

It is really pretty simple, however many photographers are baffled by it because it is fairly technical. Let's say for example that our fill light at or near the camera gives us an exposure reading of f 8. @ 1/60th sec. In this scenario, I am assuming electronic flash so the shutter speed doesn't matter. We would set the camera at f 8.

If we add a main light off to one side and set the exposure for the mainlight alone at f 8, we have established a one to two ratio. The shadow side of the subject receives one unit of light from the fill light and the highlighlight side of the subject receives one unit of light from the fill light plus one unit of light from the main light (key light is a movie term). With negative film the camera would be set at f 8. With transparancy film or digital it probably needs to be f 9.5 to keep from overexposing any white areas.

If we increase the intensity of the main light to f 11 we now have a one to three ratio. The subject receives one unit of light from the fill light plus two units of light from the mainlight. Negative film f 9.5 on the camera, digital f 11. There will be a test.

[Wil_Bloodworth]

Huh? I guess I'll get this in your class... 'cause I sure didn't get that.

- Wil

[mwaldrop]

Got it sort of. I understand the concept but not all the physics of light like how an f11 on the main light is equal to two units of light when f8 is one unit of light. I'm sure there is a formula on how the exposure value is doubled. But now I understand the ideas and the ratios make sense. Thanks.

[DEMDeepEllumMusic]

Well just look at what F stop readings mean. F 1.0 means low light F1.8 increasing light in the scene (more light means that you can step the lens down further with everything else held constant). So in his case talking about F8 and F11 there is more light in the scene with an F11 reading than an F8 reading and since your flash is set up to illuminate the whole scene you count it as say a reading of one level of light while the Key Light (be it Sunlight, Streetlights, etc or studio lights) may have a reading on the subject itself of F11 but it does not light the whole subject but just a portion of it.

BTW the key light is usually at a 45 degree angle from the subject in relation to the photographer -ie to the photographers side at 3 or 9 o'clock if the Subject were at noon and the photographer at 6 o'clock. (there have been key light discussions here before)

[brad]

Originally Posted by mwaldrop

Got it sort of. I understand the concept but not all the physics of light like how an f11 on the main light is equal to two units of light when f8 is one unit of light. I'm sure there is a formula on how the exposure value is doubled. But now I understand the ideas and the ratios make sense. Thanks.

A "stop" is doubling of the amount of light that is hitting the film/sensor for the exposure... thus changing shutter speed from 1/125 to 1/60 is roughly +1 stop. F-stops are trickier since its essentially a circle.. to double the amount of light, you have to double the area of the circle.. forget Pi because it cancels out on the doubling.. but figure that going from f/11 to f/8 is about +1 stop because 8 squared is 64 and 11 squared is 121 (with f-stops the higher the number, the smaller the opening.. the number is actually 1/11 or 1/8, which is why I usually make sure to write f-stops as f/x such as f/8).

Confused yet?

[bondarnes]

Most of what Paul and Brad said is accurate, however even though I know what they are saying it sounds confusing. The good news is that you don't have to actually know all the formulas. You only need to know how to apply those principles to your photography. More simply put: If you know what a one to three lighting ratio looks like then you don't need to know the math and physics in order to use it. Now wait until we get to the inverse square law.

[TJPhotoGuy]

Originally Posted by bondarnes

It is really pretty simple, however many photographers are baffled by it because it is fairly technical. Let's say for example that our fill light at or near the camera gives us an exposure reading of f 8. @ 1/60th sec. In this scenario, I am assuming electronic flash so the shutter speed doesn't matter.

Well that depends on the shutter speed and amount of ambient light right? i did a product shoot not long enough where we had to drag the shutter; it was an led screen and the refresh rate of it was much slower than my strobe.

Originally Posted by bondarnes

IWe would set the camera at f 8.

If we add a main light off to one side and set the exposure for the mainlight alone at f 8, we have established a one to two ratio. .

Huh? Don, why are you saying that's 1:3? It's 1:2. f/11 is one stop (double the light) over f/8, which means that the ratio is 1:2. If you're talking about the additivie nature of metering the two of them combined, it wouldn't make a whole stop of difference, typically more like a quarter, maybe a half. Plus, if you're metering for balance (as opposed to metering for exposure) then you should meter each light individually.

ANother thing is, some photographers/resources/etc would say 2:1, always using the key light to the left. And if theres' a kicker/hair/whatever, it would be in the middle, for example 2:1:2 with the last 2 being the kicker.

Also it might be noted that, lighting ratios are used to describe the interplay among lights, and have nothing to do with the camera. You can have the same lighting ratio for several different camera f-stop settings.