thanks guys for the instant reply!
following the link it becomes a bit more clear why the colours are shifted towards the blue. maybe it is worth to do some b/w exposures with the filter and add to them to some without to see if it brings out more detail.
But I will definitely check out an OIII clip in as soon as I get a hold of one.
Do you guys think a Ha-filter is of any use on an unmodded 450D?
Weather here sucks too, only clouds for the last 4 weeks
Cheers