Airylab 235mm D-ERF Filter including Custom Cell

The Airylab 235mm DERF is a specialised energy rejection filter for large aperture solar telescopes. The filter is a dielectric type similar to the Baader DERF. It's performance is tested at L/8 PTV with 90%+ transmission at the H-Alpha wavelength.

A filter of this size is ideally suited for use with a Celestron 9.25" SCT. The special design of the mounting cell only sacrifices 2mm of the maximum diameter of the filter. Alternatively it is also suitable for use with the Tecnosky 234mm Achromat.

The beauty of using a large front mounted ERF like this is that the normal night time operation of your telescope is unaffected. Simple remove the ERF!

For use with either system a telecentric is required. For the Celestron Edge SCT we recommend the Airylab 2.7x which is specially designed for the Edge series of telescopes. This can be modified to provide a 3.5x multiplier with an additional module. For a standard 'C' range SCT then the Baader TZ-3 Telecentric is recommended. For use with the Tecnosky, the Baader TZ-4 is the correct choice.

To complete your solar telescope, a rear mounted H-Alpha filter is required. For optimum performance we recommend use with a Solar Spectrum H-alpha filter. These are available in a range of bandpass and etalon sizes. For purely imaging applications we advise the Solar Observer 1 as this has an etalon suitable for use with typical high frame rate cameras. For visual use a filter with a larger etalon should be selected. Please call us for details.

The filter also passes Continuum light and so is compatible with our range of Herschel Wedges for White Light viewing and imaging.

Getting the best from a High Resolution Solar Telescope

A High Resolution Solar Telescope can provide outstanding images of our nearest star. However its additional aperture can highlight poor seeing. To ensure you get the most from your Triband SCT we recommend its use with the Airylab Solar Scintillation Monitor (SSM). This is a device that monitors seeing quality, and if used together with Airylabs Genika Software (supplied free with all Mono Point Grey (now FLIR) cameras), it will trigger capture of images at the optimum seeing level. This saves a lot of time and can almost gaurantee the quality of the images you will capture.

The Airylab 235mm Energy Rejection Filter is supplied with Spectrophotometer Report to confirm its quality. The price includes a custom made cell to house the ERF. Cells for a 9.25" SCT are usually available from stock. Cells to fit other telescopes can be made to order.

We supply the D-ERF filter together with a custom housing made to fit your telescope. The housing features a three point mounting system to securely hold the cell to your telescope. This mounting is made to be an exact fit for the dew sheild of your telescope allowing the filter to be properley secured and centered.

As all filter cells are made to order there is a lead time of approx 3-4 weeks. Please contact us so we can discuss the exact size requirements needed to fit your telescope.