One of the most frequently asked questions we receive is from photographers struggling with over-exposed windows with regards to interior photography. It’s a tricky skill to master but let’s start by identifying the problem and walking through the solutions.
The problem of over-exposed or ‘blown out’ windows is a result of the limitations of camera sensors. During a sunny day, the light level outside can be over 30 times brighter (almost 5 stops) than the room you’re in. This spread of exposure from brightest to darkest is known as ‘dynamic range’. A single image taken with a modern DSLR camera simply cannot expose for the extreme highlights of the window together with the dark shadows within the room.
Therefore we need to manually even out the light levels between the outside and the room to cater for the camera sensor’s limitations. Obviously we can’t dim the sun (besides, this would also darken the room), so we need to increase the light within the room. Together with turning on all the lights in that room, we can introduce light by means of a strobe flash or permanent fill lighting. For the purpose of this example, let’s concentrate on flash light.
Before we introduce any flash, we need to establish a ‘base shot’. In this example, I’m photographing a kitchen with amazing views. My goal is to be able to see the view through the windows. With my aperture set at f/7.1 and my ISO at 100, I adjust my shutter speed to correctly expose the windows. In doing so, the room becomes quite dark, but I can tell there is sufficient ambient light and shadow detail to be able to add some flash and raise the exposure of the kitchen sufficiently.
So, with my flash connected via a wireless trigger to my DSLR, I fire off two or three shots using different power levels on my flash. I settle at ½ power with a bare flash, positioned behind the camera, hand-held at a height of approximately six feet and pointed directly at the ceiling to diffuse the light. This is the final image.
This shot was very simple to achieve due to the open space in the room, the light-coloured walls aiding the diffusion of flash light and lack of direct sunlight through the windows. You will come across rooms which are more difficult to light correctly. Therefore you need to learn how your camera setting affect light in different ways.
Shutter speed only affects the ambient light in the scene (ambient light is any continuous light source – sunlight, lamps etc). Shutter speed does not change the affect your flash has on illuminating the room or any objects in that room. Slowing down your shutter speed can help raise the ambient light level of the room – but will therefore also raise the exposure of the windows. The reverse is also true, whereby using a faster shutter speed will darken both the room and the windows.
Aperture affects both the ambient light and flash light. Since aperture relates to the opening and closing of the lens barrel, a smaller aperture (larger F number) will reduce the amount of ambient light and flash light passing through the lens. Choosing a larger aperture (something around f/5.6 to f/7.1) will increase the exposure of both the ambient light and flash light.
ISO affects both ambient light and flash light by changing the camera sensor’s sensitivity to them.
Putting This Knowledge To Good Use
With experience, you will be able make adjustments to the ambient light and flash exposure independently by only changing your shutter speed, aperture and/or ISO settings.
For example, let’s assume we’re using the following settings to photograph a room – f/8 1/100s ISO200 and flash set to full power. If I want more flash exposure to help light the room, I have a problem. I’m already using full power. Fear not. I know that both my aperture and ISO have an affect on the amount of flash light the camera ‘sees’ (remember, aperture affects the amount of flash light travelling through the lens barrel and ISO affects the sensor’s sensitivity to it), so I could increase my ISO from 200 to 400 (one stop increase in exposure), or open up my aperture from f/8 to f/5.6 (also a one stop increase). Changing either of these settings will double the effective flash power in the scene.
However, as we know, aperture and ISO also affect the ambient light. Therefore the sunlight and the windows will also double in exposure. Not the result we wanted. If only we could reduce just this ambient light back down. But wait, we can! By increasing my shutter speed from 1/100s to 1/200s (one stop decrease in exposure), the ambient light (and therefore the window exposure) will be reduced back to where it was. Perfect!
It may seem overwhelming at first but once you get your head around shutter speed only affecting ambient exposure (ie. windows), while aperture and ISO affect both ambient and flash exposure, you will be able to balance the two sources of light with confidence and obtain ideal exposures.
Is it always possible to get a great exposure in a single image?
No. You will come across times when no matter what setting you use, or how good you are, you simply won’t be able to capture a perfect exposure from one single shot. I came across this recently when photographing a darkly lit bathroom on a very bright day.
I started with an average exposure for the room, trying to balance window exposure with shadow detail.
The problem here is very little ambient light remains in the room due to the small window, coupled with the window itself being over-exposed. Next, I increased my shutter speed to reduce the exposure of the window…
The problem above is we have literally no ambient light in the room meaning a lot of flash power will be needed. With mirrors dominating the wall, this simply wouldn’t work or look good. So let’s try reducing the shutter speed to expose for the room:
Oh dear, check out the state of the window. Completely unusable.
But wait. Here we have three images, one with a perfectly exposed window, one with perfectly exposed shadows and a third with an exposure between them both. This is where we can use a technique known as HDR or bracketing to blend the three images together. So that’s exactly what I did – no flash required! It’s by no means the best photo due to the extremes of exposure present in the scene, but it’s a happy compromise.
See my detailed video tutorial on creating natural-looking HDR interior photos here.
Don’t Obsess Over Windows!
The bottom line is this. If you’re dealing with floor-to-ceiling windows or there’s at least a half-decent view outside, then yes, you need to get a good window exposure. However, if the windows are small, or the view outside is not of any real importance, or it’s located far away at the other end of the room, then just concentrate on getting the room exposure correct and don’t fret over slightly over-exposed windows. So long as the highlights aren’t spilling over the window frame then it’s not that important. Look through any interior design magazine (example shown below from Elle Decoration) with images taken by some of the world’s best interior photographers and you’ll rarely see correctly-exposed windows.
The truth is, interior shots look better when lit using only ambient light. So, perhaps you should be using less flash anyway.
Author – Oliver Pohlmann