Having covered a couple of real-world observations of the behaviour of light it seems appropriate to look at some of the optics theory that explains how lenses are able to manipulate light to form images.
Most of the effect that a lens has on the light passing through it comes from the surface curvature of its elements. This curvature has to be both precise and very consistent as even the smallest deviations can introduce significant image distortion.
Why is some light transmitted and some light reflected at a glass surface? This is a surprisingly difficult question to answer because the nature of reflected light is not as simple as you might think.
I've just been testing the new PZD version of Tamron's 18-270mm super-zoom and I've realised that when the review of the non-PZD 18-270mm was published last year it was accompanied by the wrong MTF graph! Here, therefore, is that review again - with the correct graph this time...
Good books on The Science of Imaging are few and far between but Graham Saxby’s is one of the best. For that reason, and also because I’m honoured to be among some very high-calibre contributors whose photographs are included in the book, this ‘blog entry is an unashamed tribute to Saxby’s work.