Baader Solar Projection Screen (BSPS)

Baader Solar Projection Screen (BSPS) – observe the Sun together

The Baader Solar Projection Screen lets several people observe the Sun in white light at the same time. Instead of looking through an eyepiece, everyone views the rear-projected solar image on an enclosed screen. Sunspots, limb darkening and the progress of an eclipse can be shown clearly. Side viewing suits groups and outreach; with a tracking mount, the screen can also help monitor the Sun's position.

The screen measures 9 × 9 cm and has a T-2 (M42) connection. With a variable eyepiece-projection adapter such as the separately available Baader OPFA and suitable eyepieces, it has been tested on refractors of approximately 250 to 1200 mm focal length. Shorter focal lengths can show the full solar disc, while longer ones show a magnified portion. Telescope focal length, eyepiece and projection distance determine image size and brightness.

Buying advice and requirements

You need a refractor suitable for solar projection, a star diagonal or prism, sufficient back focus and heat-resistant components. The BSPS requires approximately 30 mm of back focus. Baader recommends focal ratios of about f/6 or slower. With faster refractors, carefully consider heat load and the complete setup; stopping down larger apertures may be advisable. A T-2 eyepiece-projection adapter and a suitable glass-and-metal eyepiece are also required. Tested options include Baader Classic Ortho eyepieces of 6, 10 or 18 mm and a 32 mm Classic Plössl. The projected solar disc must be at least 60 mm across.

Included items

Projection screen, T-2 threaded adapter and pre-cut three-piece cardboard kit with pre-fitted adhesive strips. Telescope, star diagonal/prism, eyepiece and eyepiece-projection adapter (e.g. OPFA) are not included. Read the complete manufacturer’s operating manual and assembly guide before first use.

Important safety information

Use only a combination specifically suitable for solar projection and follow the manufacturer’s instructions. Use heat-resistant glass-and-metal components; plastic in the concentrated light path may be damaged. Remove or cover the finder and other optics before pointing the telescope at the Sun. Never leave the setup unattended; regularly check that the solar image remains safely on the screen. The BSPS is a projection screen, not a solar filter for direct viewing through an eyepiece. Never look at the Sun through an unfiltered telescope.

Technical data