Hi Mirko,
I probably can't help you out too much there.
The highest magnification of the scope using the Le 5mm = 50x and I don't own a barlow or powermate at the moment either.
I only have a D5300 crop sensor camera as well, so that doesn't help you.
Try looking on CN for more info on their threads and the Borg catalog (if your good at Japanese )
Sorry