Diffraction increases as the aperture decreases to a point that diffraction dominates. The aperture size is the physical diameter not the f/stop per se. Before this gradual limit there is a sweet point for each format. I use the following as an approximation:
35mm........... f/5.6 to f/8
6x6 ...... f/8 to f/16
4"x5"............ f/11 to f/22
8"x10".......... f/16 to f/32
Ralph Lambrecht has posted in APUG a formal analysis from his book, Way Beyond Monochrome, second edition pages 136 to 139, on this subject.
Warning!! Handling a Hasselblad can be harmful to your financial well being!
Nothing beats a great piece of glass!
I leave the digital work for the urologists and proctologists.
Are you using LF or small format (35mm)?
What f/length of lens do you normally use for it or each?
Portraits feature a shallow depth of field with focus confined chiefly to the face e.g. f4 to 5.6 with 80 to 135mm lenses common (but there is no universal lens or setting for every person to follow — you find this yourself through experience).
Landscapes, with wide angle lenses in 35mm e.g. 17 to 24mm are fine af f11 to f16. Personally I use f8 to f11 only on my 24mm prime. Any deeper Av and you risk diffusion caused by light bending around the aperture blades. It is not necessary (nor effective) to go to f22 in landscape with wide- to ultrawide lenses; the latter being fine at a stop or two from wide open.
Deeper apertures right up to f45 feature as the norm in LF. You will need to actively experiment to find is right for you with a great deal of variance possible in landscape.
.::Gary Rowan Higgins
A comfort zone is a wonderful place. But nothing ever grows there.
depends on the situation and available llight but generally I like to have a very small aperture for landscapes, although if there is a lot of wind or a large body of water with movement I may choose to use a faster stop for obvious reasons. for portraits I generally shoot with a fast lens.
"The real work was thinking, just thinking." - Charles Chaplin