We enjoy shooting two Boston churches especially, Trinity Church and Old South Church, both on Copley Square. We did an earlier post on photographing churches with tilt-shift lenses that featured both structures. I have been going through our library and found the following two shots from Trinity Church. These photos are interesting because it was necessary to use HDR techniques to capture the extraordinary dynamic range of light that occurs in this church.
As most of you know, HDR is high dynamic range imaging, defined by Wikipedia as “… a set of techniques that allow a greater dynamic range of luminance between the lightest and darkest areas of an image than current standard digital imaging techniques or photographic methods. This wide dynamic range allows HDR images to more accurately represent the range of intensity levels found in real scenes.” HDR images are created in software by merging multiple exposures of the same scene that were captured at different exposures. This is not a new concept; in 1850, Gustave Le Gray was able to render seascapes showing both the sky and the sea. Le Gray used one negative for the sky, and another one with a longer exposure for the sea, and combined the two in a single picture in positive. The advent of high-resolution digital imaging and powerful computing has led to great advancements in HDR.
Both shots in this post used the Adobe Photoshop “Merge to HDR” feature, which I have found to be the application that can best achieve naturalistic results. In the case of these two photos of Trinity Church, the vibrant colors exist in the original and are not a product of over-saturation and excessive HDR processing.
As a point of reference, this next image shows the four different versions of the photo that were used to create the “Clerestory details” shot above. It is possible to combine almost any number of shots (I once used 9 in a single image), but this shot required four.
It is also possible to combine elements of different exposures of the same photograph by using the Adobe “layers” features. By creating a layer mask of a region – a window, for example – it is possible to replace a blown out window from one shot with a properly-exposed version from another. I’ll do a post on this soon, because it is possible to get results that are almost perfect.