Another comment I came across when scanning through the opinions about LR CC HDR was concerning the result of merging just two or three different exposures versus a stack of 5 or more images. People stated that it made no difference to them whether they stacked three or eight images from a common stack, and that the result seemed the same.

I will take a quick look at that situation...

Just Three Exposures or a Stack of Nine - What gives...?

These two images are both generated from the same stack of nine images, with each image being 2/3rds of a stop apart. The left one was merged from the full stack, while the right one was merged from just three exposures (max / mid / min) of the stack. Then the same develop settings were applied to both images.

At first sight, the tonality and colours are equal. There isn't any noticeable difference at the full image view, but things become a tad different once you zoom in to actual pixels.

Remember, both images are straight from the LR conversion with all develop settings being equal. The difference in quality at the pixel level is staggering, so the large stack size definitely pays off with a much lower amount of noise.

The three image stack shows a much higher amount of noise than the full stack, which becomes pretty obvious if you think about the settings which are applied equal to both images. The full stack has much more information available without the need to digitally alter and modify the pixel data as much as what is done to the pixel data of the small stack.

The Final Result

The final result from the stack of nine, after a slight luminance mask treatment and some dodging and burning in Photoshop.