The ToupTek PureSight A1 is a 2-inch double-band filter designed for imaging emission nebulae. It transmits the Hα and OIII lines with a nominal bandwidth of 5 nm.
CHF 229.00incl. Swiss VAT
Part Number TOUP-PURESIGHT-A1-DUAL-NARROWBAND-FILTER
Will be ordered for you
Timeframe: 10 days to 3 weeks
Estimated shipping: Between November 13 and 18, 2026
The ToupTek PureSight A1 is a 2-inch double-band filter designed for imaging emission nebulae. It transmits the Hα and OIII lines with a nominal bandwidth of 5 nm.
Its fused silica substrate is combined with an IAD coating. The aluminum alloy mount features an M48 × 0.75 thread and a clear aperture of 43.9 mm.
During installation, the threaded end must face the sensor.
The dual-band principle involves allowing two spectral regions to pass through the same filter. This reference refers to the Hα and OIII lines, at 656.3 nm and 500.7 nm, respectively. It thus differs from a set of three SHO filters used separately. The nominal width of 5 nm describes the selected bands; it does not represent either the diameter of the filter or the thickness of its glass.
The specified tolerances must be maintained with respect to the nominal width: 5.0 nm ± 1.2 and 5.0 nm ± 1, depending on the band. The specified transmission is greater than or equal to 90 %. These values describe the filter; they do not guarantee photographic results under all conditions. The exposure settings must be adjusted to suit the instrument, the camera, the subject, and the sky brightness.
The 2-inch commercial size and the M48 × 0.75 thread are designed for mechanical integration. The specified effective aperture is 43.9 mm; this should not be confused with the nominal diameter of the size. The fused silica substrate is 2.00 mm thick, with a tolerance of ±0.1 mm. Its IAD coating and aluminum alloy mount are part of the design described by ToupTek.
The manufacturer specifies the installation orientation: the threaded side must face the sensor. Before installation, verify that the filter holder or accessory you have chosen is compatible with this configuration. This data sheet applies to the filter alone, not to a filter drawer, filter wheel, or filter assembly. For very quick optical setup, confirm that the filter is compatible with your instrument rather than assuming universal compatibility based solely on the “dual-band” designation.
| Targeted rays | Hα 656.3 nm; OIII 500.7 nm |
|---|---|
| FWHM Bandwidth | 5.0 nm ± 1.2; 5.0 nm ± 1 |
| Transmission | ≥ 90 % |
| Thickness | 2.00 mm ± 0.1 |
| Format | 2 inches |
| Thread | M48 × 0.75 |
| Useful opening | 43.9 mm |
| Substrate | Fused silica |
