Jon Tarrant

Drawing on the two previous postings in this 'blog we are now able to create a basic model for image formation. This is not a thorough approach to image formation…

We have an explanation for why light bends when it moves across a boundary between two different media but is there any predictable pattern to the amount that any given…

Far cheaper than Canon's f/1.2 equivalent, but still a mighty good performer for a more than reasonable price

The price tag might not suit everyone's budget, but this optic's performance is hard to argue with

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…

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…

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…

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…

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…

Why do astronomers use telescopes? The answer is NOT “to make distant things look closer” but rather to make fainter things look brighter. In that respect, telescope lenses are very…

You may sometimes have a choice between two similar lenses; one with a fixed aperture, the other with a variable aperture, priced higher and lower respectively. Which is the better…

Some time ago I discussed the optimum size for a pinhole to be used in digital pinhole-camera photography. I’ve now done some practical work, the results of which are presented…