Filters < Astronomy Type of build line filter

Line filters selectively allow only light from a specific spectral line to pass through. OIII, SII and H-alpha filters are especially popular.

The Roman numerals III and II indicate the degree of ionisation of the chemical element that produces the spectral line. So OIII (pronounce oh three) stands for doubly ionised oxygen, and SII for singly ionised sulphur. OI and SI indicate the electrically neutral atoms.

Line filters are ideal for the visual observation and photography of emission nebulae, supernova remnants and planetary nebulae, since these objects produce defined spectral lines. Star clusters and galaxies on the other hand have a continuous spectrum. For these, filters that generally suppress the sky’s brightness (CLS or UHC filters) are more suitable.

Example of an emission line spectrum (source: Wikipedia)

Filters

Type of build: line filter

Optolong

Filters L-Ultimate 2"

$ 430.00

Omegon

Filters OIII Filter 2"

$ 99.00

Omegon

Filters OIII filter 1.25''

$ 79.00

DayStar

QUARK H-alpha filter,chromosphere

$ 1,910.00

Optolong

Filters L-Synergy 2"

$ 394.00

Omegon

Filters 7nm H-alpha 1.25 pro filter

$ 189.00

Optolong

Filters SHO Filter Kit 7nm 2"

$ 830.00

Optolong

Filters SHO 3nm 2"

$ 1,200.00

Omegon

Filters Pro 2'' H-Beta filter

$ 129.00

Optolong

Filters L-Ultimate 1,25"

$ 322.00

Astronomik

Filters 1.25" OIII filter

$ 119.00

Omegon

Filters Pro 1.25'' H-Beta filter

$ 99.00

Omegon

Filters Pro Veil H-Alpha OIII 7nm 2''

$ 199.00

Optolong

Filters L2 Dual-Combo Set 2"

$ 700.00

DayStar

Filters 0.5Å H-alpha Quantum PE filter

$ 28,200.00

ZWO

Filters Narrowband Filter Set H-alpha, SII, OIII 2"

$ 1,200.00

Lunt Solar Systems

Filters H-alpha double-stack for LS60FHa

RRP: $ 3,580.00

Our price:

Baader

Filters H-alpha/OIII/SII CMOS Ultra-Narrowband 50x50mm

$ 1,450.00

Astronomik

Filters H-alpha 12nm MaxFR XT Clip Sony alpha 7

$ 590.00

Baader

Filters H-alpha/OIII/SII CMOS f/2 Ultra-Highspeed 36mm

$ 1,120.00

Lunt Solar Systems

Filters Ca-K module with 6mm blocking filter in star diagonal for 2" focuser

RRP: $ 2,270.00

Our price:

Astronomik

Filters 2" OIII filter

$ 239.00

Baader

Filters H-alpha/OIII/SII CMOS f/2 Ultra-Highspeed 31mm

$ 940.00

Astronomik

Filters H-alpha 12nm MaxFR XT Clip Nikon XL

$ 590.00

Astronomik

Filters H-alpha 12nm MaxFR XT Clip Nikon Z XL

$ 590.00

Lunt Solar Systems