TeleVue Bandmate Type 2 H-Beta 2" - Line Filter

TeleVue Bandmate Type 2 H-Beta 2″ : Lijnfilter: H-beta-lijnfilter in 2 inch

The Bandmate Type 2 H-beta in 2 inch combines the specialist filter with large overview eyepieces, exactly what the expansive California Nebula demands.

This filter also fits directly into the nose of a 2-inch zenith mirror, so it remains mounted when changing eyepieces.

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 H-beta filter is used for

The H-beta filter isolates the hydrogen line at 486 nanometers. The list of objects it asks for is short but famous: the Horsehead Nebula, the California Nebula, and some faint reflection nebulae that remain invisible without this filter.

For that handful of targets, it is indispensable, beyond that it does little. An H-beta is therefore the third nebulae filter in a collection, after a UHC and an OIII, and requires a substantial telescope aperture and a dark sky.

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

• The California Nebula with a large field
• ✓ Large Dobsonian telescopes under a dark sky
• ✓ Fixed mount in the zenith mirror
• As a first mist filter
• ✗ Small telescopes and a city sky

Specifications

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