This came up as a question on one of the user groups I follow; How do you shoot something happening inside a room when you also want to retain the view outside the room and how do you track the changing exterior light level and colour temperature?
I’m going to assume that this isn’t a scenario where you can add silks or flags to reduce the light on the exterior elements that are needed to be seen. This type of shoot is always challenging. Generally the amount of light outside, during the day will be very high, especially in summer or when the sky is clear. If the windows are relatively small then they won’t let much light into the interior so we are going to have to do something to address the imbalance between the interior and exterior light.
If the space has large picture windows, then more natural light will come into the room, but with so much glass it may be difficult to avoid the interior elements such as the cast or performers from being silhouetted against the bright windows and exterior. So, what can we do?
A high dynamic range camera does help, especially if the window is small and can be isolated in post production for separate treatment compared to the rest of the shot. But often even a camera with a huge range doesn’t really help because the contrast in the shot is just too extreme to look nice. For a small window adding a little bit of diffusion via a filter such as a 1/4 or 1/8th black promist or supermist can help soften the edges of the otherwise bright window making the image look less forced or less digital.
One approach is to add ND film to the windows to reduce the amount of light coming through the windows. This is very effective and reduces the amount of light that needs to be added to the interior. But it can be expensive or impractical with very large windows. You can be super fancy and add a polariser film to the window and then another polariser on the camera, by turning the polariser on the camera you can quickly adjust how much of the exterior is visible! Instead of ND film you can also add black scrim (a mesh like material with lots of holes in it), this has some advantages as it tends to be a bit cheaper than ND gel and it isn’t shiny like ND.
Even with large wrap around windows without ND or mesh over the windows the exterior light levels are likely to be significantly higher than the interior levels and it typically takes a significant amount of additional light to balance this. If you don’t achieve a good balance then the exterior will be over exposed or the interior in silhouette no matter how much DR the camera has and simply stopping down or ND’ing down won’t help.
The exterior colour temperature probably won’t vary that much during the day, other than early morning or late afternoon unless the weather changes significantly. The angles of the exterior shadows will shift as the sun moves across the sky, as will the amount of light from the sun that enters the space, but there is nothing you can do about that if you need to see the exterior. Dimmable lights will allow you to control the interior/exterior brightness balance and bi-colour lights should be sufficient to track the exterior colour temperature differences throughout the day. If using multiple lights that can be remotely controlled if there is an app for the lights you are using you can probably create a group for all the lights allowing quick global changes of the colour temp and intensity. Or perhaps you can get them all connected up via CMX.
This type of shot will always be challenging to pull of well. I normally use large soft lights to lift the overall interior light level, something like the Nanlux Dyno’s or perhaps some Nanlux Evokes with softboxes. On a budget you might be able to get away with some Forza 720’s or FC-500B with soft boxes. The number of light you will need will depend on the size of the space, the size of the window and the time of year you are shooting.