The ideal HDR image combines bracketed shots that, cumulatively, capture the full dynamic range of the scene. After shooting, these are aligned and adjusted using software to create a finished photo.
There are no hard and fast rules about how many frames or what range of exposures you need—it depends on the highlight-to-shadow ratio of the scene, and what you want your final image to look like. Still, more captures are better, since you can always delete unused files but you can’t effectively add tonality or detail you never captured. Check the camera’s histogram as you’re shooting to ensure that each shot covers a specific tonal range.
Andy Ryan’s trio of bracketed shots—exposed to capture details in the highlights, midtones, and shadows—let him use the best lighting (over the top from the back) and camera angle for the overall composition, even though it left the interior of the molten cake in shadow. Blending them brought out the texture and color of the cake’s chocolate center, while maintaining the clean highlights of the white plates and tablecloth, along with accurate midtones.