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"

$ 465.00

Omegon

Filters OIII filter 1.25''

$ 89.00

Optolong

Filters SHO Filter Kit 7nm 2"

$ 840.00

Optolong

Filters SII Filter 2"

RRP: $ 279.00

Our price:

Astronomik

Filters 1.25" OIII filter

$ 116.00

Optolong

Filters L-Ultimate 1,25"

$ 302.00

Omegon

Filters Pro 1.25'' H-Beta filter

$ 99.00

DayStar

QUARK H-alpha filter, prominences

$ 1,790.00

DayStar

Filters 0.5Å H-alpha Quantum PE filter

$ 30,400.00

Omegon

Filters 7nm H-alpha 1.25 pro filter

$ 199.00

Baader

Filters H-alpha/OIII/SII CMOS f/2 Highspeed 1.25"

$ 489.00

Omegon

Filters Pro 2'' SII CCD filter

$ 189.00

DayStar

Combo QUARK H-Alpha solar filter, for chromosphere

$ 1,790.00

Baader

Filters H-alpha CMOS Narrowband 1.25"

$ 162.00

Omegon

Filters Pro 1.25'' OIII CCD filter

$ 129.00

Baader

Filters OIII CMOS Narrowband 1.25"

$ 159.00

Astronomik

Filters HSO 6nm 36mm

$ 880.00

Omegon

Filters Pro OIII 7nm Filter 1,25"

RRP: $ 179.00

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Omegon

Filters Pro SII 7nm Filter 1.25"

RRP: $ 179.00

Our price:

Astronomik

Filters H-alpha 12nm CCD Clip-Filter Sony alpha

$ 395.00

Astronomik

Filters HSO 12nm 36mm

$ 590.00

Baader

Filters H-alpha/OIII/SII CMOS Narrowband 2"

$ 770.00

Astronomik

Filters 2" OIII filter

$ 232.00

Baader

Filters H-alpha/OIII/SII CMOS Ultra-Narrowband 2"

$ 1,220.00

Optolong

Filters SHO Filter Kit 1,25"

$ 620.00