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)
Optolong
Filters L-Ultimate 2"
$ 420.00
ready for shipping in 24
h
Optolong
Filters SHO Filter Kit 3nm 2"
$ 1,360.00
ready for shipping in 3-5
weeks
Optolong
Filters SHO Filter Kit 2"
$ 760.00
ready for shipping in 24
h
Omegon
Filters Pro 2'' SII CCD filter
( 1 / 5 )
$ 189.00
ready for shipping in 24
h
Baader
Filters H-alpha/OIII/SII CMOS f/2 Ultra-Highspeed 2"
$ 1,160.00
ready for shipping in 1-2
weeks
Baader
Filters H-alpha/OIII/SII CMOS Ultra-Narrowband 2"
$ 1,100.00
ready for shipping in 1-2
weeks
Omegon
Filters Pro 1.25'' OIII CCD filter
$ 129.00
ready for shipping in 24
h
Explore Scientific
Filters SII 6.5nm 2"
RRP:
$ 242.00
Our price:
$ 122.00
ready for shipping in 24
h
Explore Scientific
Filters H-alpha 7nm 2"
$ 242.00
ready for shipping in 24
h
IDAS
Filters SHO Filter Set 50.8mm
$ 1,340.00
ready for shipping in 3-5
weeks
Optolong
Filters SII Filter 2"
RRP:
$ 252.00
Our price:
$ 242.00
ready for shipping in 24
h
Explore Scientific
Filters H-alpha 12nm 1.25"
$ 168.00
ready for shipping in 1-2
weeks
Explore Scientific
Filters OIII 6.5nm 1.25"
RRP:
$ 168.00
Our price:
$ 85.00
ready for shipping in 24
h
Astronomik
Filters 2" OIII filter
$ 210.00
ready for shipping in 24
h
Omegon
Filters Pro 1.25'' SII CCD filter
$ 129.00
ready for shipping in 24
h
Explore Scientific
Filters SII 12nm 2"
RRP:
$ 199.00
Our price:
$ 100.00
ready for shipping in 1-2
weeks
Baader
Filters H-alpha/OIII/SII CMOS f/2 Highspeed 2"
$ 730.00
ready for shipping in 1-2
weeks
Optolong
SII Filters 1.25"
$ 152.00
ready for shipping in 24
h
Baader
Filters H-alpha/OIII/SII CMOS Narrowband 2"
$ 700.00
ready for shipping in 1-2
weeks
Omegon
Filters Pro 1.25'' H-alpha filter
$ 149.00
ready for shipping in 24
h
Omegon
Filters Pro 1.25'' H-Beta filter
$ 99.00
ready for shipping in 24
h
Optolong
Filters SHO Filter Kit 1,25"
$ 560.00
ready for shipping in 24
h
Omegon
Filters OIII Filter 2"
( 5 / 5 )
$ 119.00
ready for shipping in 24
h
Explore Scientific
Filters 2" H-Beta filter
RRP:
$ 128.00
Our price:
$ 79.00
ready for shipping in 24
h
ZWO
Filters Filter set H-alpha, SII, OIII 36mm unmounted
RRP:
$ 770.00
Our price:
$ 702.00
ready for shipping in 3-5
weeks
Baader
Filters H-alpha/OIII/SII CMOS f/2 Ultra-Highspeed 65x65mm
$ 1,760.00
ready for shipping in 1-2
weeks
Omegon
Filters Pro 2'' OIII CCD filter
$ 179.00
ready for shipping in 24
h
Baader
Filters H-alpha/OIII/SII CMOS f/3 Ultra-Highspeed 65x65mm
$ 1,660.00
ready for shipping in 1-2
weeks
Baader
Filters H-alpha/OIII/SII CMOS Ultra-Narrowband 65x65mm
$ 1,650.00
ready for shipping in 1-2
weeks
Omegon
Filters UHC Filter, 2"
$ 99.00
ready for shipping in 24
h
ZWO
Filters 1.25" filter set: H-alpha, SII, OIII
RRP:
$ 600.00
Our price:
$ 548.00
ready for shipping in 3-5
weeks
Explore Scientific
Filters H-Beta filter 1.25''
RRP:
$ 105.00
Our price:
$ 53.00
ready for shipping in 1-2
weeks
Omegon
Filters Pro 2'' H-alpha filter
$ 209.00
Product can be shipped as of 15.12.2024
Astronomik
Filters H-alpha 6nm CCD MaxFR 2"
$ 720.00
ready for shipping in 3-7
days
Omegon
Filters OIII filter 1.25''
$ 89.00
ready for shipping in 24
h
Optolong
Filters L-Ultimate 1,25"
$ 273.00
ready for shipping in 24
h