What is better, SFD or a stack made of multiple photos?


I’ve discussed the SFD mode, which was introduced with Sigma sd Quattro cameras, late last year. Since I’m experimenting with Affinity Photo as of late, I wanted to do a little comparison of the program’s stacking feature and the SFD mode.

In the following comparison we are going to determine which one looks best: SFD, a stack of twelve photos in AP or a single photo. Just as a reminder, in the SFD mode the camera captures seven photos with different shutter speeds (meaning properly exposed, underexposed and overexposed), which are then used to create a single huge X3I raw file. This is done automatically in camera. With seven vs. twelve photos one would assume that the photo created using Affinity Photo ought to look best, but is that really the case? Let’s take a look at the crops.

SFD mode

Stack of 12 photos / Affinity Photo

Single capture

Those of you who would like to take a look at full res photos can do so on flickr. There you will not only find full res versions of the SFD and AP photos but also of the twelve photos used for stacking.

I believe there is no need to explain the results in much detail. The single photo looks the worst. In addition to luminance noise chromatic noise is also clearly recognizable. The stack of 12 photos has a much lower level of noise. Chromatic as well as luminance noise aren’t a real issue here. The black background was brightened up in both photos in Lightroom, in order to make the differences easier to spot. Surprisingly the photo taken in SFD mode is the cleanest of the three. I didn’t expect that Sigma would be able to improve noise performance with only seven photos by that much. Furthermore this image was not brightened up, because it already had better dynamic range than the other two photos.

 

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