aha, good things take time

I did not assign a star first. After the first installation (which was very easy) was to me this thing suspect. Fearing for the lens, I did not want to proceed to brutal and have the non-turning can be accepted or re-removing ability. When shooting with flash, I then had these super shadow. I then something stronger tackled (after reading your advice, reviews are helpful, thank you).
On the subject of transport: after this operation, it can be screwed also to the rear.
Because of fear for Lens, a star deduction, otherwise nothing to complain about.
ps: the price-performance ratio for accessories, brands should take a leaf