As part of my work, I have to shoot the interior of vehicles in lighting that is truly harsh and awful. I would routinely use off camera flash to try to illuminate the interiors of vehicles sitting in the blazing sun in a salvage yard, with the hopes that I could balance the strong exterior lighting with the dark, cave-like interior. Even bouncing flash off of the interior headliner would still lead to uneven lighting and more headaches. Same goes with a very high lumen output continuous light headlamp.
HDR techniques seem like a natural solution, but there are some limitations associated with the exercise. Vehicle interiors are very tight and cramped spaces to begin with - add to that the change in space associated with a vehicle that has been heavily damaged in a crash, and you have limited options in terms of your choice of equipment. I have been using a Canon 15mm f/2.8 full frame fisheye for a while now, mounted on a 5D or 5DII. This works, but suffers from fisheye distortion and horrendous CA and purple fringing - in the context of HDR, this only gets worse.
Well, I saved and scrimped and broke down and recently purchased a Zeiss 15mm f/2.8. This lens is expensive, for me, but has abilities that border on impossible.
Here is a quick test of the lens on the 5DII body, shooting the interior of a car in harsh midday sunlight. The exposure range was 1/30s to 1/2000s to capture the scene (7 images @ 1EV). Interiors of wrecked cars can provide a lot of information about what happened to the occupants in a crash, so it is particularly important to be able to capture all of the interior detail and preserve that data for forensic analysis.
The Zeiss 15mm is in a class by itself. The flare and fringing control is ridiculous and the lack of pixel crushing distortion is really critical to getting as many useful pixels out of each image as possible. The color rendering and sharpness to the edge of the image is incredible as well. This permits me to capture full-frame high-resolution images of the entire cockpit of the vehicle in one shot, with a working distance of less than 1.5 feet. Astounding. The HDR data captured in this scene was shot handheld, with manual focus (the Zeiss lenses do not have autofocus). This is also critical, because autofocus often breaks down in such dark settings, unless you use a camera-mounted flash with focus assist. The typical technique I use for focus with a Zeiss lens is to employ LiveView at 10x magnification - I will also use a focus loupe if the camera is mounted to a tripod.
In this study, the bright speculars on the interior trim were left to be specular, but detail was retained in the center console and shift knob. The deep recesses of the footwells were rendered perfectly (including the red backpack and green water bottle) without the purplish noisy color shifting that often results when lenses start freaking out during super huge overexposures used to get shadow areas properly exposed. No flare, no purple fringing - none of these images underwent any lens profile correction in ACR.
This is not the lens for everyone, nor is the scene something that you are going to shoot everyday, but the practical aspects of HDR imaging cannot be overstated.
Just thought I'd share this little nugget of information. I should probably clean my car, too.
kirk
