"PREVIEW DEPTH OF FIELD" function - what's the point? It's ALWAYS previewing.

[Astigmatism]

Why is there a "PREVIEW DEPTH OF FIELD" function? I am ALWAYS seeing the effect of the DoF. As I turn the aperture ring I see more or less blur on things not at the focused distance. In fact, if I turn the camera round, I also see the blades of the aperture stop move in and out as I turn the ring.

What does the function change? Seems like nothing, as far as I have been able to notice.

If it matters, this is on an X-T4 with a Fuji 35 f/1.4 lens.

Thanks!

[Greybeard]

In aperture priority - set the lens wide open - choose a scene with objects at different distances - now press the button you have assigned to "PREVIEW DEPTH OF FIELD" and the effect should be obvious. 

(I checked it with X-S10 but X-T4 should be much the same - its not something I ever use as half press will do the same and also focus on the subject)

 

Edited August 15, 2022 by Greybeard

[BobJ]

Surely there isn't any point, as when you put a half pressure on the shutter release the lens stops down to is working aperture and so you get the same function.