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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.

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

Let me share with you how I use flash to help me achieve the look I am after and without having to do the mental calculations of light ratios!

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.

Image: Left: without a diffuser. Right: with a diffuser.

Left: without a diffuser. Right: with a diffuser.

I only use a flash bare and pointed towards the camera when I am using it as a kicker light and want starburst effects coming from it.

#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.

For portraits, I find that the greater the contrast between the dark background and the illumination of the subject with a flash gun, the more I dislike the image. For dancing shots (like at a wedding), however, where I want to illuminate the subject well and freeze the action, I DO point my flash directly at the subject, stop down my aperture to between f/5.6 and f/8 and lower my shutter speed between 1/20th and 1/60th in order to capture ambient light and light trails or background blurring to give the effect of movement.

Image: This image was created using a bare bulb flash (no diffuser) located behind and pointing dire...

This image was created using a bare bulb flash (no diffuser) located behind and pointing directly at the couple (off-camera flash). I also had a second flash on-camera with a diffuser, and the flash aimed upward.

Image: This image was created with a diffused flash pointed directly at the couple (camera in front...

This image was created with a diffused flash pointed directly at the couple (camera in front of the couple, flash on-camera) while they were dancing. The motion blur was created by using a slow shutter speed and “dragging the shutter” after the flash has fired.

What I’m after is always a natural look, which, depending on where the main light is coming from, may not be achieved well without some kind of fill or reflected light to illuminate areas that are too dark for my intentions. This is the reason why I always bounce or angle my flash gun for most scenarios other than dancing as explained above.

#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.

Image: My speedlight with the white bounce card extended.

My speedlight with the white bounce card extended.

As an aside, I use this setup for off-camera flash too. When I’m putting two speedlights opposite each other in a room to provide directional light during speeches, I point the flash heads upwards and pull out the diffuser so that all the reflected light is pointed inwards towards the center of the room.

#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.

In the photos below, bright sunlight was coming from camera right at 45 degrees on a bright day. All I wanted was a bit of fill flash on their shadowed faces, just enough to lift the shadows a tad. What I really wanted to avoid was for the image to look like there was another light source other than that from the sun. To achieve this, I angled my speedlight upwards towards the back by one increment.

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

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 softbox 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.

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

Compare the two images below. The one on the left was taken in a big open space with a dense foliage background which blocked the light. There was enough light here to illuminate their faces that I could have done away with the flash altogether, but I pointed the flash backward to add just a tiny bit of light over my head. I don’t think it made a huge difference but it made me feel better and consistent!

The image on the right was taken in a shaded open area surrounded by tall trees which diffused the light coming from the background. Without the trees, it would have had the unfiltered effect as above, but despite the trees, this is still very much a backlit position as the background was very bright still. More fill light was needed there so I pointed the speedlight slightly upwards, with one increment down towards the subjects but not directly at their faces.

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

You can see the same flash angle as above on these close-up portraits below.

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

Make it moody

In the same spot as above, I wanted a look that was a little moodier than those close-ups so I pointed the speedlight directly upwards this time. So although their faces are still amply lit up, the image to feels like they are being enveloped by the diffused light behind them.

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

Tricky situations

The couple wanted a shot showing the lake and the trees in the far distance. The distance was too great to get the couple and the background sharp enough without using a really small aperture and a lot of artificial light (flash). Note that we were also in the shaded part of the lake which made it more difficult. I decided therefore that I would take a cozy shot that focused mainly on the background. The couple looking towards the trees, although they are not the lit focal point, they are still clearly visible and sharp. I pointed the speedlight slightly forwards to give them just a hint of light and shot with a small aperture.

Contrast the top image below to the photo directly underneath it where the depth of field has changed massively – the background now is blurry and the couple is in focus. This had the same angle of flash, slightly forwards, but of course, my camera settings changed to a wider aperture and lower ISO to balance the exposure. Now with the couple still in the same shaded spot, the angled flash was clearly essential here. Had I pointed the flash directly to their faces, it would have been too obvious and would kill the natural light ambiance that I was aiming for.

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

For this ring shot below, we sat on a bench with the sunlight coming from camera left. I put the ring on my phone to get a dark background and a nice reflection. With ring shots, I always stop down to at least f/7 with a macro lens. Therefore I need to make sure there is plenty of light for the shot as macro lenses tend to suck light.

I also always use a speedlight pointed directly opposite the main light. So in this case where the light is at camera left at 8 o’clock (if you’re looking at a clock face with the diamond at 6 o’clock), I swiveled my flash head to the opposite at around 4 o’clock to give off a bit of reflected light on the right side of the ring.

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

Likewise, on the photo below, you can clearly see where the sunlight is coming from so I pointed my speedlight slightly upwards to camera left, opposite the sunlight. This angle helped me achieve a gradual decrease of light from right to left as opposed to a dramatic one where you can see a clear cut-off from light to dark.

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

Your turn to try doing fill flash

If you haven’t tried using flash like this before, I encourage you to do so. Experiment and see how it could work for you. You don’t need to learn the lighting ratios and calculations off by heart to be able to get images you are after, although that could be handy.

Sometimes all you need is confidence, common sense, and a willingness to try. I hope you found this little tutorial useful. If you have more tips, share them in the comments below.

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Lily Sawyer
Lily Sawyer

is a wedding and portrait photographer based in London. Her absolute favourite past time is going on “mummy” dates with her kids and husband. Other than that, as a homebody, she is content curled up on the sofa, hot chocolate in hand, watching films with her family whenever she has a free weekend. Check out her work on www.lilysawyer.com Follow her on her fave social media platform Instagram.