The logical thought process behind the notion totally escapes me on how using five, seven exposure bracket is true HDR. Unless you have absolute control over the lighting (studio) and the object is stationary, the created image from the number of exposures used would technically be imperfect. Movement from non-stationary items or subjects (people, clouds), changes in the scene’s exposure value during the creation of the sequence (shadows from clouds moving across the scene), cycling of flourescent and halogen lights and other changes to a scene during creation of the sequence would be apparent if scrutinized closely. This form of “true hdr” is rather faux because it creates an image from several moments in time and not just a single one. These should be called ‘compression HDR’ images.

To accomplish these ‘purests’ notion of “true HDR”, one would need seven cameras with the exact same focal length lenses focus at the exact same distance with the exposures set whatever value apart (1/3 stop). The shutters would have to be fired at the exact same time to accomplish exactly what a camera RAW file does. Even then the slight difference in angle depending on the lens choice would create a 3D effect. In this example, all seven cameras would capture one moment in time – not several.

Making an HDR image from a single camera RAW files is the purest way of creating an HDR image. It will be even cooler once camera makers figure out a way to increase the dynamic range from 5 to 7 stops. Camera RAW files are unaffected by caused by gradual shift in depth of field if the aperture is used to control the bracketed exposures or motion blur caused by irratic movent of objects during the bracketing process.

Using a single RAW file to create an HDR image is the purest way of accomplishing the task of creating a high dynamic range image from a single moment in time. Doing it any other way is almost a lie from a purest standpoint