How to Use an On-Camera Speedlight as Fill Flash for Portraits

Using a flash or speedlight on-camera can be daunting at first. This was certainly how I felt when I first purchased my Nikon speedlight. My biggest worry was calculating all the light ratios involved to get a proper exposure as you cannot take into account the actual flash output when metering in-camera. I was also nervous about using a light meter – all that trial and error and faffing, the thought of it all used to make me quake in my boots and swear I’d forever be a natural light photographer. But that was not to be, thankfully.

My main reservation about using flash is the harshness of the light. I hate the “flashed” look on people’s faces, the shadows under the jaws, the bright circular catchlights right in the middle of the iris. As well, the flatness of the face with the direct flash obliterating all possibility of sculpting shadows on the face.

But I live in London where it rains quite a bit, it’s hardly sunny at all, and half the year is cold. All these factors affect natural light and I felt I just had to put aside my reservations and take the leap. And I’m so glad I did.

Some notes about using flash

As photographers, we have to learn a host of technical knowledge on top of our creative vision. That involves a lot of trial and error to find which methods work for you. It’s no different when it comes to camera settings and flash power.

We know that we can adjust the three factors in the exposure triangle to get the right exposure for our intended look. For example, if you want a darker background with less ambient light, you can increase your speed while keeping the aperture and ISO the same. But if you want ambient light in the background showing through with less dark shadows, you can lower your speed instead while still keeping the aperture the same.

Similarly, if you want a deeper depth of field at a smaller aperture, you may need to increase your ISO and adjust your speed. But keeping the same aperture, if you want to minimize any noise at high ISO, you could lower your speed instead.

Adding the flash power as a 4th factor is no different. You may choose to keep adjusting your flash power to get your desired exposure, or like me, you may want to leave your flash power at a constant unless the changes in light requirement are dramatic, and adjust the exposure triangle instead. As long as you have ample understanding of the basics of exposure, play around with what works best for you that will benefit your efficiency and workflow as a photographer as well as keeping consistent with your style.

#1 Put a diffuser on the flash

It may only be a little plastic thing that goes on top the flash head but I find it makes a difference.  The light is less harsh – I know many will disagree about whether it softens the light or not as that is mainly due to the size of light and distance to subject  – but I notice a softness from a diffused flash head compared to a bare one.

#2 Control the flash manually

Set your flash to manual and choose the power. I’m usually at 1/32 or 1/16 and leave it there. Adjust the flash power only when absolutely necessary. Instead, make the frequent necessary adjustments to your camera settings.

Now I know there are many big fans of ETTL / TTL mode out there. I have tried it too. However, I have gone back to Manual as I find the TTL does not give me the look I want. Essentially, I only want my flash to be a fill light, not the main light and never too strong so that you can see a huge difference between the light coming from the flash and the ambient light. The ETTL / TTL mode is too smart for my needs and increases the output to a pretty high level if it senses that the ambient light is too weak, and vice versa. I felt I’d get an inconsistent output of light for the look I am after although that output may be “correct” in terms of the calculations.

#3 Bounce it

On some newer models, there is also a little white pull-out bounce card that is extremely useful if your ceilings are too high for the light to bounce off or you just want to point reflected light in a particular direction. When I shoot weddings where the rooms have very high ceilings or dark beams and ceilings. So I pull out the bounce card and use it to deflect the light coming from the flash. The handy swivel action helps me direct the reflected light wherever I want it to go.

#4 Angle it

The head of most speedlights can swivel right and left up to 90 degrees each way and forward and upward to 90 degrees in incremental angles. It is an awesome functionality that you should take advantage of especially for fill flash.

Flash as a fill light

As you can see, these photos below have very strong sunlight coming directly at the subjects and towards the camera, a very strong backlit light. It is extremely difficult to overpower this type of light without using a strong flash.  What I did was angle myself slightly to one side and pointed my flash directly at the subjects’ faces to try and counteract the sunlight.

This is when I adjust my flash power and increase it accordingly. The result is not as clean and sharp as if I had a big soft box firing at 70% ratio to the sun’s power but it still shows the faces clearly enough with some diffused hazy light in the background, which was also my intention for these shots.