I fly an inspire 2 with the 5s camera and am wondering what the drawback would be with me changing my aperture setting to around F16 or so on a sunny day rather than using a ND filter? I’m very interested to hear if this approach is sensible. Feedback is appreciated.
Your question has generated some really excellent discussion here - good advice from knowledgeable people! I'll add just a comment or two.
I wouldn't presume to argue against the use of ND filters. They have their uses. But I would just add that every time you add glass into the light path you add a new source of image distortion. How much depends on the quality of the "new" glass; and how noticeable it's going to be probably depends on how good your image would have started out in the first place - without that "new" glass.
Also - It's true that the sharpest image a lens will render usually occurs around f5.6 if the lens has a multiple leaf-style aperture apparatus because the ratio of non image-forming (that which is being scattered by the edges of the aperture plates) to image-forming light (that which you intentionally allowing into the lens) is lowest at that setting. But sometimes depth-of-field is more important in the image; and smaller apertures (larger f-numbers) yield greater depth of field.
It just depends on what you're trying to accomplish with your imagery.