I have slipped in a magnifying glass into shows...LOL! I want people to come up to my images and explore all aspect of it...otherwise it is like driving the loop around Yosemite Valley with a video camera hanging out the window, and just looking at the scenery on the telly when one gets home.
While I'm here, Brian, I didn't mean anything by it. Leigh, thanks four your comments, I would agree. I think that lens manufacturers have been fairly opaque with these kinds of details, or at least kept them very technical. When I looked into this for the Rodenstock lenses, all I could find was MTF (I think I have that acronym right). There wasn't a comparison of the different apertures. Maybe its just me...
Anyway, informative discussion.
Museum Quality Drum Scanning and Printing
Ordinarily, MTF curves are provided at two or three specific apertures (designated 'K' for no obvious reason).
One K value is wide open, one is usually f/16 or f/22, and there may be a third.
Performance at other apertures is left as an exercise for the student.
MTF curves are published because they're very easy to generate automatically, by computer.
There's no manual intervention required, except to set the aperture on manual lenses.
You can't infer anything about diffraction from the MTF data by any technique known to me.
Perhaps others know how to do it.
Diffraction is usually a smaller effect than inadequate depth of field. But inadequate DOF is often a smaller effect than subject movement in the longer exposures required by small apertures.
I try to pay attention to the biggest effects first. If that limits print size, then that is a better outcome than an image that can't be printed at all.
I don't have a favorite aperture, in the way I have a favorite ice cream flavor. For any given image, I have a favorite look, and that usually dictates the aperture. But always it is a dynamic balance between competing influences.
Everybody gets that bit, but often I think people don't consider which of those influences have the most visible effects. Diffraction effects are usually the least significant.
Rick "thinking aperture is an objective choice based on a subjective intention" Denney
Before you criticize someone, walk a mile in their shoes. That way when you do criticize them you'll be
a mile away and you'll have their shoes.
I don't have a favorite aperture, because aperture is dictated by the type of image I am trying to create.
But I do have a favorite default aperture that I begin with for each image. I start at the lens' sharpest aperture. If that provides the DOF that I want, then that is ideal because I get to shoot at the lens' optimal aperture. But If I need more DOF, I stop down. If I need less DOF, I open up. Stopping down and opening up from the sharpest aperture both involve compromises in term of image quality. But the importance of DOF generally eclipses those compromises.