This page illustrates misunderstanding number 10 on the
If lenses, at reduced apertures, only use a small central portion of the front element,
Figure 1. A lens with a piece of paper stuck on the front element.
then from where comes the dark square in this picture?
Figure 2. Picture taken with the lens at f/22.
spherical aberration | astigmatism and field curvature | distortion | chromatic aberrations | vignetting | lens hoods | flare | filter flare | depth of field | dof equations | vwdof | bokeh | spurious resolution | center of perspective | MTF measurements | corrections | misconceptions
home | about | photos | optics | faq | sitemap