Re: (IAAC) Markarian 205 - 8inch F/10

Welcome back, Nick!

You are right - the views of many objects are worsened by narrowband filters. I 
guess I was proposing that the reason for those worsened views was generally 
just reduced light transmission overall - rather than any reduced contrast of 
the object/feature relative to background. But I wonder if there may be areas 
of some of these nebulae (Cat's Eye in particular) which do in fact emit their 
light mainly at wavelengths outside the Hbeta and OIII regions?

One thing for certain, there are lots of "emission" nebulae whose light is 
actually more than half reflected (continuum) starlight: using even a wideband 
filter on these can make them disappear entirely (or make many of their 
features - the primarily reflected ones - disappear from the object).

As a matter of fact, one of my favorite observing projects is trying to 
distinguish and map out the complex, intermingled dust- and gas-heavy 
components of brighter nebulae, using nothing but "UHC blinking".

Clear skies,