Over the years I have seen many studio portraits shot on white backdrops where the photographer didn’t manage to get the backdrop to come out pure white in the photo. And this doesn’t happen because the backdrop itself wasn’t really white since most of the time the photographer is shooting the subject against a roll of pure white studio backdrop paper. So the problem occurs because the backdrop wasn’t lit correctly and then comes out looking a bit less than pure white in the photo.

So what are some of the issues that can cause this problem?

1 – Not enough power being supplied to the light(s) being used to light up the backdrop.
2 – A shutter speed that is too fast for the duration of the studio lights.
3 – Uneven coverage of light onto the backdrop.

One of the sad problems with not getting the backdrop fully white in the photo is that you may need to spend a lot of time post processing each shot to whiten the backdrop. And that can end up being a lot of time wasted unnecessarily. So I am going to explain how I normally set up my white backdrop for perfect results every time and avoid the problems I mentioned above.

The first thing I do is setup two lights on either side of the backdrop, each fitted with an opaque bounce umbrella.

The bounce umbrellas help prevent any light from the studio flashes shooting through the umbrella, going into your lens, and causing lens flare. This is important because the lights that will be hitting the backdrop will be placed far in front of your camera and lens flare could occur if you were using translucent umbrellas instead. Bounce umbrellas also ensure all the light from the flashes is bounced back onto the backdrop and none of the light’s power is wasted coming out of the back side of the umbrella.

So I place the 2 lights equal to one another’s position on each side of the backdrop and the lights at a height that is about half of the height of the backdrop itself. I then aim the lights pretty much straight towards the middle of the backdrop to try and get an equal amount of light hitting the backdrop from top to bottom on both sides.

I then meter the two lights so that the output of the two lights combined is about 2 stops brighter than the aperture setting I plan to be shooting the camera at. So for example, if I plan to shoot at F/8 then I would try to meter the two lights onto the backdrop at F/16. By setting the power of the lights on the backdrop 2 stops above my aperture setting it helps to ensure the backdrop will be blown out completely and turn up as pure white in the photo. However, you don’t want to go much more than 2 stops above your aperture setting because too much light and you will get some light bounce back from the backdrop and onto the model which could soften the edges of the model’s skin as well as perhaps cause some lens flare. Usually with up to 2 stops more power than the camera’s setting aperture though and there is not problem, especially if the subject is positioned well enough in front at a distance of about 3-4 meters away from the backdrop.

The next thing I do is check my shutter speed to make sure that my shutter speed isn’t too fast for the duration of the lights. What I mean is that each brand of studio light emits the light for a different duration of time. Some are faster than others. But you want to make sure that the studio flash has enough time to fully emit the light at the power setting you have chosen without the shutter opening and closing too quickly before the flash fully goes off. In terms of my flashes, they have a rather long duration. So a shutter speed of 1/160th and above and it means the photo wont pickup the full power emitted by the flashes in time. So I normally shoot at 1/125th as a rule of thumb and never have a problem with pretty much any brand of studio flashes. If your shutter speed is too fast if often doesn’t matter how much power you are using, you will always lose some light and may never get a fully white backdrop in your photos. So a shutter speed that isn’t too fast is the key for studio flashes.

Now, once I have my lights setup, metered and set at the correct power level, and I have my shutter speed set correctly, I do a test shot of the backdrop by itself. I do this by using a very handy feature available in most DSLR cameras. I enable the “Highlight Alert” function in the camera menu. This flashes white on the preview screen within any areas of the photo that are blown out. In this case I want to have the entire backdrop pure white so I basically want it to be fully blown out in the test shot and the highlight alert to be fully blinking over the entire backdrop.

So once I take my test shot, and see it on the camera preview screen, I look to see that the entire backdrop is blown out and flashing on the preview screen. Any areas of the backdrop which aren’t flashing are indications of an area of the backdrop which won’t be fully white in my photo. So if this happens then I go back and adjust the position of my umbrellas. I do this by tilting the umbrellas a bit more in the direction of the area in the test photo which isn’t fully blown out. Then I take another test shot and, if all is well, then I am ready to start shooting my subject on my pure white backdrop.