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"
$ 422.00
Omegon
Filters OIII Filter 2"
$ 99.00
Omegon
Filters OIII filter 1.25''
$ 79.00
Omegon
Filters 7nm H-alpha 1.25 pro filter
$ 189.00
Omegon
Filters Pro 2'' H-Beta filter
$ 129.00
Optolong
Filters L-Ultimate 1,25"
$ 316.00
Astronomik
Filters 1.25" OIII filter
$ 117.00
Omegon
Filters Pro 1.25'' H-Beta filter
$ 99.00
Omegon
Filters Pro Veil H-Alpha OIII 7nm 2''
$ 199.00
ZWO
Filters Narrowband Filter Set H-alpha, SII, OIII 2"
$ 1,180.00
ZWO
Filters Filter set H-alpha, SII, OIII 36mm unmounted
$ 830.00
Omegon
Filters Pro 2'' SII CCD filter
$ 179.00
Askar
Filters Color Magic D2 OIII/SII Duo 2"
$ 457.00
Astronomik
Filters H-alpha 12nm MaxFR XT Clip Sony alpha 7
$ 580.00
Astronomik
Filters H-alpha 12nm CCD Clip Canon EOS APS-C
$ 234.00
Astronomik
Filters 2" OIII filter
$ 234.00
Lunt Solar Systems
Filters LS50C double-stack filter
RRP:
$ 2,110.00
Our price:
$ 1,710.00
Omegon
Filters Pro 1.25'' SII CCD filter
$ 129.00
Optolong
Filters SHO Filter Kit 1,25"
$ 590.00
Optolong
Filters SHO Filter Kit 7nm 2"
$ 810.00
DayStar
QUARK H-alpha filter, prominences
$ 1,870.00
Optolong
Filters SII 6.5nm 2"
$ 258.00
DayStar
QUARK Magnesium I (b2) Line
$ 2,110.00
ZWO
Filters Filter CH4 1.25"
$ 164.00
Baader
Filters H-alpha 20nm 1.25"
$ 111.00
DayStar
Combo QUARK H-Alpha solar filter, for chromosphere
$ 1,870.00
Optolong
Filters L-Synergy 2"
$ 387.00
Omegon
Filters Pro OIII 7nm Filter 1,25"
$ 189.00
Baader
Filters K-LINE filter gestackt, 1 ¼ " (with 3,8 astro+solarly 200x290mm photo film)
$ 335.00
Omegon
Filters Pro SII 7nm Filter 1.25"
$ 189.00
Astronomik
Filters H-alpha 12nm CCD Clip-Filter Sony alpha
$ 399.00
Astronomik
Filters CCD Canon EOS XL H-Alpha clip-filter
$ 375.00
Baader
Filters H-alpha/OIII/SII CMOS Ultra-Narrowband 2"
$ 1,230.00
Omegon
Filters Pro 1.25'' OIII CCD filter
$ 129.00
DayStar
QUARK Calcium-H-Line
$ 1,870.00
