Pau, It is interesting that you use a 70-200 zoom lens. I though we should only use constant lenses (e.g. 200 mm). Have you posted photos or details of your rig somewhere?
Anyway it seems that in my case the problem was at least partly in the tube lens (see below). I have not tried yet the 50X... It will be even harder I think.
ChrisR, yes I still keep the iris a little bit stopped down to reduce reflections, but you are right about new adapter rings. Will try to work them with some black mat spray.
NOW THE NEW ENCOURAGING TESTS:
I thought trying a new tube lens that I received: Componon 150 mm instead of Raynox 250 mm.
This tube lens focused at about 120 mm distance from sensor. The results are below and are much much better now (compare with the photos above), although still not at the level I would have wished.
Can we conclude that for some reason Raynox 250 is not a good tube lens with Nikon 10x? Has anyone combined these two lenses with good results?
