400 mm DO

When this lens was new I read some bad reviews about its sharpness esp. compared to the 300 mm 2.8. Now some have told me that the lens has gotten better.
Is it true? What can you expect from this lens if you buy one today?
Is it 2 or 3 stop IS?

Liu

The DO lenses have a diffractive optics element that makes them relatively lightweight compared to full refractive optics. The bad thing most people say about the DO lenses is the strange bokeh it produces. They do tend to have somewhat less contrast than refractive lenses.

I have read from someone who uses the 400 DO that the main good thing about that lens is it can be carried around and is totally hand holdable.

I would, for less money, get a 300/2.8 + 1.4xTC