Changing aperture after composing and metering

[batmura]

Does changing aperture after metering, composing, and attaching an ND filter affect image quality? Say I compose and meter at f-8, put on my filter, and once it's totally dark in the viewfinder, I decide to stop down to f-11? Will this have any impact on my focus point or image sharpness?

 

[Derrel]

Hmmm....well, I suppose there could be some very minor focus shift when stopping down from f/8 to f/11, but I think it would unlikely cause much of an effect. Many lenses have some focus shift when stopping down from wide-open aperture to smaller apertures like say, f/8. The point of sharpest focus, the focus point, ought to stay pretty much the same,m but there will be more depth of field. If one looks at actual lens tests of small-format cameras, like say modern, high megapixel d-slr cameras, f/11 is usually an f/stop that has is negatively impacted by diffraction--and f/11 often starts to have worse resolution than wider apertures, like f8 or f/5.6. Still, increased depth of field can be more important to have than ultimate resolution.

 

[KmH]

If it's totally dark in the viewfinder, it's totally dark on the image sensor too when the shutter is released.

If you stop down it just gets darker.