Baader D-ERF Energy Rejection Filters for H-alpha Solar Observation Size:160mm High Speed – Rotates up

High Speed – Rotates up to 7

operated by 2XAAA batteries (not included)

compatibility with longer focal length eyepieces

Photosphere filter is an assistant filter

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Baader D-ERF Energy Rejection Filters for H-alpha Solar Observation Size:160mm High Speed – Rotates upBaader Energy Rejection Filter (D ERF) H Alpha Solar Observation Filter The Baader Energy Rejection Filter (D ERF) is specifically designed for H alpha solar observation, allowing telescopes to achieve full aperture resolving power. This filter significantly reduces the thermal energy entering the telescope, protecting your solar spectrum filter and minimizing thermally induced seeing effects for a more stable and detailed observation experience.