I'm reading lens reviews and I have encountered the term 'centering quality' a few times (e.g. http://www.photozone.de/sony_nex/720-sony50f18nex?start=1).
What does this term mean? What are the factors that influence the effect?
I'm reading lens reviews and I have encountered the term 'centering quality' a few times (e.g. http://www.photozone.de/sony_nex/720-sony50f18nex?start=1).
What does this term mean? What are the factors that influence the effect?
"Centering quality" is the degree to which the lens produces symmetrical focusing performance in all radial directions from the centre.That is, focus or resolution may change as you progress along a radial line from the centre, but in a perfectly centred lens the performance along all radial paths will be equal.
There's a reasonably good discussion here - Do it yourself centering sanity check .
The questions and answers are arguably as useful as the actual article.
The site provides a very simple template which can be printed to assist testing.
In each test image 4 x black & white boundaries are arranged radially and the user assesses how sharp they are relatively.