Posted 23 December 2012 - 09:45 AM
Elaborating just a bit further on the virtues of quality comet filters, specifically the one offered by Lumicon, they offer considerably more potential advantages in the hands of someone at least moderately familiar with comets and their physical make-up than may initially meet the eye.
Not only do they allow one to define whether the comet's main outgasing products are predominately gas, or dust, but they will often bring out very subtle internal features and details that are otherwise overwhelmed by the coma's overall brightness.
Often a comet filter will reveal individual filamentary streams of inoized gas leaving the inner coma and extending in a directly anti-solar direction perhaps otherwise hidden within the general glow of the inner tail (often composed of a combination of gas and dust). Likewise, dust features like the jets, arcs and related feature such as were visible in comets Bennett, West, Halley, et al. can become apparent in dusty comets by virtue of the dimming/suppression of the overall brightness of the coma is lowered.
And as I've already pointed out, these filters can be of considerable assistance in first detecting very bright comets situated against a highly luminous sky immediate after sunset, or just before sunrise. The suppression of much of the background sky's brightness can render visible a potentially spectacular object that would otherwise be lost in the brilliant light of twilight to other observers for days yet to come.
Among serious comet observers quality comet filters, such as the Lumicon product, are often taken to be an essential standard accessory.