I saved for an Astronomic UHC filter. They recommend a minimum diameter scope . Seem to have the greatest light transmission %. A couple of years ago at Astrofest we compared a Lumicon uhc to a Astronmic on IC5148 in GRUS. The view through the Lumi was dimmer . and confirm buy a experienced observer
But having said that I would agree with ausastronomer about the 70mm "poor little Guy"
