SolarSpectrum Research Grade 0.4x Telecompressor 2

• Like the TZ-3 telecentric, the RG 0.4x Telecompressor features 46mm clear aperture throughout, perfectly suitable even for large SolarSpectrum RG46 Research Grade H-alpha Filters
• Working distance: 74mm (Distance to the camera sensor), optimized for videography and full solar disc imaging. Ø 16 mm corrected image field in conjunction with the TZ-3
• Mounts straight onto the eyepiece-side of the body of the SolarSpectrum filter and reduces the telecentric extended f/ratio by a factor of 0.4
• 2" external threads on both sides, fitting the SolarSpectrum Universal Flange Adapter #2958240
• The RG 0.4x Telecompressor serves to adjust the focal length in order to improve poor seeing conditions and / or to enlarge the field of view for photographic or lucky imaging applications.

Baader Planetarium has designed this new optimized telecentric system for use with Solar Spectrum H-Alpha systems.  A telecentric system is used to convert shorter focal ratio telescopes to the desired f/25 or greater beam needed by the rear mounted Solar Spectrum filter.  More than a barlow lens or barlow lens based system, the Baader telecentric ensures that the output beam maintains a consistent normal incident angle across the full filter width.  The result is a consistent bandwidth and high image contrast across the field of view.  This lens system has been optimized to maintain an exceedingly high optical quality for dedicated solar use (>99% strehl at 656.3nm).  Simpler barlow or barlow-based systems are not able to produce this level of accuracy or telecentricity.  Hard Dielectric IR coatings further help to reject IR energy and protect the rear etalon from excessive heat energy. 

Solar Spectrum H-alpha filters require parallel light with a ray path of at least f/30. This is achieved by a focal length with our telecentric systems (and possibly also by dimming the lens with the iris). Because of the focal length extension in many telescopes the sun's full disc us unable to be viewed even when using eyepieces with f = 30 to 35 mm.

Both Solar Spectrum Telecompressors are mounted eyepiece-sided directly on the filter and reduce the previously extended focal length again by a factor of 0.4x (#2459260) and 0.7x (#2459259) with the result that now the whole solar disk with prominences is visible again.

A telecompressor is slso used to adjust the focal length to possibly poor seeing conditions and / or enlarging the field for photographic- or webcam applications.

To attach the telecompressor use our 2″ Universal flange (# 295 8240); it attaches with four screws directly onto the filter housing (see illustration), the telecompressor is mounted directly into the 2″ thread of the universal flange. The main thread of the compressor also is a 2″ male thread. This can be changed if necessary with parts from our T-2 accessories system either to a T-2 internal or external thread.