Omegon Helievo 172 mm Solar Filter (164–188 mm)

Omegon Helievo 172 – mounted solar filter

The Omegon Helievo 172 is designed for white-light solar observing with a compatible telescope. Its pre-mounted cell makes installation at the front of the optical tube straightforward. Fit is determined by the actual outside diameter of the telescope tube or dew shield: this version fits 164–188 mm. Please measure your telescope carefully before ordering.

The clear aperture is 172 mm. An integrated AstroSolar filter film reduces incoming sunlight with a stated filter factor of 100,000. The film can be replaced. Three adjustment screws with plastic tips secure the cell to the tube; tighten them evenly and without excessive force. Before every use, check that the filter is firmly attached and that the film is undamaged. Use it only over the objective at the front of the telescope, and never observe the Sun without a properly fitted, undamaged objective solar filter.

Technical data

Choosing the correct fit

The 172 mm size refers to the clear aperture, while 164–188 mm is the supported outside diameter of the tube or dew shield. These measurements are different. Check the attachment before pointing the telescope at the Sun. An objective solar filter does not replace an eyepiece-end filter; never use a solar filter at the eyepiece.