Hi Chris
Steve makes good sense here. When I first stared I bought a heap of eyepieces through sheer ignorance. To make it worse I bought from different manufactures and different types (what does parfocal mean folks
oops). I ended up with 7, 9,12mm vixen LV's , a 40mm celestron elux, a 7 - 21mm zoom, 14mm pentex XW, 2 meade 4000 26mm and series 5000 26mm as well as a 9mm illuminated reticle. It was only after this spending spree that I learnt about telextenders (fancy word for barlows).
My scope is at F10 which is the same as yours. I only use the 40, 26 and 14mm eyepieces for visual the rest stay in the box. If I use these with a 2X barlow I effectively have 20, 13 and 7mm eyepieces as well. At 7mm I am really pushing the scopes ability (10" lx200r at about 360 X mag) and that is about as high as I would go in the city even when seeing is good and the moon is below the horizon, you just loose too much light. The 40mm delivers a reasonable wide field considering the F10 focal ratio.
All you really need are 2 or 3 good quality eyepieces and a 2X barlow. Try to get a parfocal set which means you will not have to re-focus much as you change the eyepieces to get the best view.
The main filters I use are red/green/light blue and yellow wrattens (good for planets) and I also have astronomik CLS (broadband for light pollution) and OIII and Hb narrow band filters (only useful when used from a very dark site to view specific objects). I have others for CCD work but have found the wrattens and CLS filters to be of the greatest use visually in the city.
Good Luck
