Flame Nebula & Filter Comparison
The recent pictures I have posted of the Horsehead, Flame and Rosette have all been done using a UHC filter. Another one is attached through the window with the 80mm without the focal reducer.
I tried without the filter and could hardly see anything.
I found this, which is a very interesting comparison of various filters with an assortment of nebulae:
As you can see in this trial, the UHC is the winner!