ZWO 31mm H-alpha 7nm Narrowband Filter - UNMOUNTED - Mark II 3x barlow lens 5/15/20/25/30/50kHz Scrambler function 8 Group’s

5/15/20/25/30/50kHz Scrambler function 8 Group’s Scrambler Wide/Narrow Band Yes P1-P5 with programmable functions Yes Voice pressure /expansion function Yes Repeater offset shift Yes Contact book Yes ANI ID Yes DTMF/2 tone/5 tone coder Yes Remote kill/ stun/ activate/ revive Yes Keypad lock function Yes 0-9 SQL grade setting Yes 1750MHz tone Yes Reverse frequency Yes Auto Power off Yes VOX function Yes Busy lockout function Yes Scanning function Yes COMP function Yes Monitor function Yes CTCSS/DCS setting and scanning Yes TOT function Yes Battery voltage display Yes Channel name display/editing Yes Emergency alarm Yes Keypad lock function Yes Power saving function Yes LCD Backlight Yes Chinese and English voice prompt Yes PC software programmable Yes Specification Frequency stability ±2

Narrowband filters are used to create high contrast deep sky images of certain objects

the Horsehead Nebula (IC 434)

So it is not a "must

Does the ASIAIR Plus need internet

ZWO 31mm H-alpha 7nm Narrowband Filter - UNMOUNTED - Mark II 3x barlow lens 5/15/20/25/30/50kHz Scrambler function 8 Group’sNarrowband filters are used to create high contrast deep sky images of certain objects, mainly emission and diffuse nebulae (i. e. Veil Nebula, M42 Orion Nebula, North America Nebula, Horsehead Nebula) or planetary nebulae (i. e. M27 Dumbbell nebula, M57 Ring Nebula, Helix Nebula), just to mention few of well known nebulosities. Narroband filter sets are sometimes used instead of LRGB filter sets and sometimes in combination with them However, if you