Today’s Question: Would it be good to minimize capture sharpening, including the sharpening applied by default in Lightroom [or Adobe Camera Raw] until after merging multiple exposures into a high dynamic range [HDR] image?
Tim’s Quick Answer: In general I do recommend that you minimize sharpening for the initial captures that will assembled into an HDR image, although in actual practice this depends on the specific workflow (and software) you’re using to assemble the initial HDR image.
More Detail: In many cases when you assemble an HDR image, each original raw captures is rendered to produce full pixel values for the high dynamic range result. As a result, it can be advantageous to ensure those original captures have minimal adjustments, or at least only adjustments that will be beneficial.
When it comes to sharpening, I prefer not to apply sharpening to the initial captures as part of this process. In other words, I want to combine the pixel values based on the original capture data, and then apply sharpening and other corrective adjustments after the HDR image has been created.
With some software the issue of minimizing initial processing is not actually a factor. For example, if you process several exposures into an HDR image using the “Photo Merge” feature in Lightroom, the resulting image will be an Adobe DNG file with any prior adjustments stored as metadata. In other words, prior adjustments won’t actually harm an HDR image created in this way.
As a perhaps more dramatic example, if you convert the original captures to black and white in Lightroom, and then merge those black and white captures to an HDR image in Lightroom, the HDR image will also be black and white. However, because the adjustments you applied are actually just metadata values, you can switch to the Color setting for the Treatment control in the Basic set of adjustments, and the black and white HDR image will return to the original color from your original captures.
So, as a general concept I recommend minimizing the processing you apply to the raw captures you will merge into an HDR result. However, in some cases this issue is not a concern based on the workflow of certain software (such as Lightroom) when creating the initial HDR image.