So I did a couple of jobs today, determined to just use the 40-150 as needed and what do you know. In the field the lens proved again how good it is to use.
Taking out the odd flaring (?*), the lens shows the usual qualities of an Olympus lens, high sharpness, good micro contrast and an ability to render a nice image. An image that suits the design ideal of the specific lens.
A few things need to be kept in mind before you go down a dead end path like this.
1. The effect of depth of field, focus errors and atmospheric conditions are easy to underestimate even with M43. A 150mm f2.8 is a shallow depth rendering instrument, especially at closer distances, in any format.
2. The end product will rarely be scrutinised by anyone as closely as you will when “testing” gear.
3. You will tend to find what you are looking for, especially in the short term, so don’t trust those observations when they come too easily. You need your observations come and in their own time before you are sure. In the mean time, you get your images taken.
*The problem, if there is one may lie with a damaged filter, the same one it has had on since day one, which seems to have a light smudging or smokiness on its surface.