14. Lenses
Focal Length and Handheld Photography
Minimum Shutter-speed= 1 / focal length
E.g.: 200mm lens needs at least a shutter-speed of 1/200.
15. Lenses
Focal Length and Handheld Photography
Using a Vibration Reduction (VR / IS) lens allows 4 more stops
E.g.: 200mm lens needs at least a shutter-speed of 1/.......
20. Lenses
Terminology: Bokeh
Bokeh describes the rendition of out-of-focus points of light.
Bokeh is different from sharpness. Sharpness is what happens at the point of best focus.
Bokeh is what happens away from the point of best focus.
23. Lenses
Terminology: Vignetting
Vignetting means that there's a decreasing (=darker) illumination towards the image corners.
Vignetting problems can easily be recognized in plain colored area like the sky as shown the the
pictures below - the pictures in the 2nd row illustrate the effective illumination as it would be present
when shooting e.g. a white paper.