TeleVue Bandmate Type 2 OIII 1.25" - Line Filter

TeleVue Bandmate Type 2 OIII 1.25": Line Filter: OIII Line Filter for Planetary Nebulae

The Bandmate Type 2 OIII in 1.25 inch is the contrast filter for planetary nebulae and supernova remnants. It screws into any 1.25 inch eyepiece with a filter thread.

Under a city sky, this filter makes the difference between an empty spot and a visible Veil Nebula; under a dark sky, it brings out structure that wouldn't otherwise be there.

How a line filter gains contrast

Emission nebulae emit their light in a handful of narrow spectral lines. Light pollution and the natural airglow do not; they spread out over the entire spectrum. A line filter lets only the nebula lines through and blocks the rest.

The result is not a brighter image, but a darker background from which the nebula emerges. With a Dutch or Belgian sky, that difference is significant.

Type 2: Built by Astronomik to TeleVue specifications

For the Bandmate Type 2 line, TeleVue is collaborating with filter specialist Astronomik. The transmission bands lie exactly on the emission lines, with transmission in the passband exceeding ninety percent and a sharp cutoff outside of it.

The coating is polished and parfocal with TeleVue eyepieces, so focusing is hardly necessary after screwing it on. The filter housing has standard threads, making it compatible with any eyepiece with filter threads of the corresponding size.

What an OIII filter is used for

The OIII filter lets the two lines of doubly ionized oxygen through, at 496 and 501 nanometers. This is the light from planetary nebulae and supernova remnants: the Veil Nebula, the Dumbbell Nebula, and the Ring Nebula gain spectacular contrast with it.

Be sure to factor in the price each line filter asks for: stars and galaxies are heavily dimmed. This is a specialized nebula filter, not an all-around filter; those who want broader should look at the Nebustar UHC.

Featured accessories

The filter screws into the filter thread of each eyepiece in the corresponding size, and therefore also into the TeleVue eyepieces from our range. For use with a 2-inch diagonal mirror, a 2-inch filter can be inserted directly into the mirror nose.

For whom yes and for whom no

• Planetary nebulae and supernova remnants
• ✓ Observing under a light-polluted sky
• ✓ Telescopes from approximately 100 mm aperture
• Galaxies and star clusters, which dampen every line filter
• ✗ Those looking for an all-around nebula filter, check out the Nebustar UHC

Specifications

More filters can be found on the Telescope filters page. The complete lineup of this merk is available on the TeleVue merk Page.