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"

$ 454.00

Omegon

Filters OIII Filter 2"

$ 119.00

Optolong

Filters SHO Filter Kit 7nm 2"

$ 820.00

Omegon

Filters OIII filter 1.25''

$ 89.00

Optolong

Filters SII Filter 2"

RRP: $ 272.00

Our price:

Baader

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

$ 477.00

Optolong

Filters L-Ultimate 1,25"

$ 295.00

DayStar

Combo QUARK H-Alpha solar filter, for chromosphere

RRP: $ 2,040.00

Our price:

Omegon

Filters Pro 1.25'' H-Beta filter

$ 99.00

Optolong

Filters SHO Filter Kit 3nm 2"

$ 1,470.00

Coronado

Filters Double Stacking Etalon Solarmax II PST 40mm

$ 1,700.00

DayStar

Filters 0.5Å H-alpha Quantum PE filter

$ 29,700.00

Baader

Solar Filter SunDancer II TZ-3S H-alpha 2"/1.25"

$ 4,040.00

STC

Filters Duo-NB Clip Canon (Full Frame)

$ 540.00

Omegon

Filters 7nm H-alpha 1.25 pro filter

$ 199.00

Omegon

Filters Pro 2'' SII CCD filter

$ 189.00

Astronomik

Filters 1.25" OIII filter

$ 113.00

Omegon

Filters Pro 1.25'' OIII CCD filter

$ 129.00

Astronomik

Filters H-alpha 6nm CCD Clip Canon EOS R XL

$ 610.00

Optolong

SII Filters 1.25"

$ 164.00

Astronomik

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

$ 386.00

Baader

Filters K-LINE filter gestackt, 1 ¼ " (with 3,8 astro+solarly 200x290mm photo film)

$ 325.00

Baader

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

$ 790.00

Omegon

Filters Pro 2'' H-Beta filter

$ 139.00

Omegon

Filters Pro 2'' H-alpha filter

$ 209.00

Baader