In the nebula filters category you will find both broadband and line filters. The latter only selectively allow the light of a certain spectral line through. OIII and H alpha filters are especially popular. Many deep sky objects will only reveal their full glory when observing using these filters!
As the name suggests, wideband and narrowband filters pass a wider range and narrower of the spectrum. They are used primarily to suppress light pollution.

Omegon
Filters Pro 2'' CLS filter
$ 99.00
ready for shipping in 24
h

Omegon
Filters Pro 1.25'' OIII CCD filter
Sale price:
$ 139.00
$ 119.00
ready for shipping in 24
h

Omegon
Filters Pro 2'' OIII CCD filter
Sale price:
$ 179.00
$ 159.00
ready for shipping in 24
h

Omegon
Filters Pro 2'' SII CCD filter
( 1 / 5 )
$ 189.00
Sale price:
$ 189.00
$ 169.00
ready for shipping in 24
h

Omegon
Filters OIII filter 1.25''
$ 89.00
ready for shipping in 24
h

Baader
Filters H-alpha CMOS f/2 Highspeed 31mm
$ 167.00
ready for shipping in 1-2
weeks

Baader
Filters H-alpha CMOS f/2 Highspeed 36mm
Sale price:
$ 189.00
$ 117.12
ready for shipping in 24
h

Baader
Filters SII CMOS Ultra-Narrowband 31mm
Sale price:
$ 286.00
$ 170.85
ready for shipping in 24
h

Baader
Filters f/2 Highspeed SII CMOS 50.4mm
Sale price:
$ 272.00
$ 170.85
ready for shipping in 24
h

Baader
Filters H-alpha/OIII/SII CMOS f/2 Highspeed 31mm
$ 479.00
ready for shipping in 1-2
weeks

Baader
Filters OIII CMOS Narrowband 50x50mm
Sale price:
$ 307.00
$ 192.34
ready for shipping in 24
h

Baader
Filters OIII CMOS Narrowband 65x65mm
Sale price:
$ 382.00
$ 235.32
ready for shipping in 24
h

Baader
Filters OIII CMOS f/2 Highspeed 31mm
Sale price:
$ 169.00
$ 106.38
ready for shipping in 24
h

Baader
Filters OIII CMOS f/2 Highspeed 36mm
$ 186.00
ready for shipping in 24
h

Baader
Filters OIII CMOS f/2 Highspeed 50.4mm
Sale price:
$ 271.00
$ 170.85
ready for shipping in 24
h

Baader
Filters OIII CMOS f/2 Highspeed 50x50mm
Sale price:
$ 310.00
$ 192.34
ready for shipping in 24
h

Baader
Filters OIII CMOS f/2 Highspeed 65x65mm
Sale price:
$ 388.00
$ 235.32
ready for shipping in 24
h

Baader
Filters OIII CMOS f/2 Ultra-Highspeed 31mm
Sale price:
$ 290.00
$ 181.59
ready for shipping in 24
h

Baader
Filters OIII CMOS f/2 Ultra-Highspeed 36mm
$ 341.00
ready for shipping in 1-2
weeks

Baader
Filters OIII CMOS f/2 Ultra-Highspeed 50.4mm
$ 416.00
ready for shipping in 24
h

Baader
Filters OIII CMOS f/2 Ultra-Highspeed 50x50mm
Sale price:
$ 429.00
$ 235.32
ready for shipping in 24
h

Baader
Filters H-alpha CMOS Narrowband 50x50mm
Sale price:
$ 301.00
$ 181.59
ready for shipping in 24
h

Baader
Filters H-alpha CMOS Narrowband 65x65mm
Sale price:
$ 387.00
$ 235.32
ready for shipping in 24
h

Baader
Filters H-alpha CMOS Ultra-Narrowband 50.4mm
$ 446.00
ready for shipping in 24
h

Baader
Filters H-alpha CMOS f/2 Highspeed 50x50mm
Sale price:
$ 317.00
$ 192.34
ready for shipping in 24
h

Baader
Filters H-alpha CMOS f/2 Highspeed 65x65mm
$ 393.00
ready for shipping in 24
h

Baader
Filters H-alpha CMOS f/2 Ultra-Highspeed 31mm
Sale price:
$ 307.00
$ 192.34
ready for shipping in 24
h

Baader
Filters H-alpha CMOS f/2 Ultra-Highspeed 36mm
$ 371.00
ready for shipping in 1-2
weeks

Baader
Filters SII CMOS Narrowband 50x50mm
Sale price:
$ 306.00
$ 192.34
ready for shipping in 24
h

Baader
Filters SII CMOS Narrowband 65x65mm
Sale price:
$ 380.00
$ 235.32
ready for shipping in 24
h

Baader
Filters f/2 Highspeed SII CMOS 1.25"
$ 158.00
ready for shipping in 24
h

Baader
Filters SII CMOS f/2 Highspeed 31mm
Sale price:
$ 170.00
$ 127.87
ready for shipping in 24
h

Baader
Filters SII CMOS f/2 Highspeed 36mm
Sale price:
$ 187.00
$ 117.12
ready for shipping in 24
h

Baader
Filters SII CMOS f/2 Highspeed 50x50mm
Sale price:
$ 311.00
$ 192.34
ready for shipping in 24
h

Baader
Filters SII CMOS f/2 Highspeed 65x65mm
Sale price:
$ 389.00
$ 235.32
ready for shipping in 24
h

Baader
Filters SII CMOS f/2 Ultra-Highspeed 31mm
Sale price:
$ 288.00
$ 181.59
ready for shipping in 24
h