Solar telescope with the 120 mm f/5 from SkyWatcher

Dear Mr. Kloss,

About the solar telescope with the 120 mm f/5 from SkyWatcher:

To save costs, I use a relatively small D-ERF, namely 110 mm in diameter. Because I didn't want to stop down the 120 mm aperture, the D-ERF is installed behind the front lens, specifically behind the first aperture. The apertures are simply clamped and easily accessible. The ERF fits perfectly IN the aperture with just a few strips of adhesive felt. When mounting the ERF + aperture into the tube, the aperture blades clamp evenly around the ERF. I had good experiences with a sub-aperture ERF last year, so I didn't have any major concerns. The ERF is also highly reflective of thermal radiation (IR), so the heat doesn't penetrate very far into the system.

The lens cell is pre-marked and carefully screwed back into place after the ERF is installed.

At the other end, a 2" TeleVue Powermate is used for the first time to bring the SW120 to f/10, necessary for what's behind it: the small etalon of the PST. Focusing is critical, but with a little finesse, it can be done quite well with the single-speed focuser.

Also included is a picture of the etalon with a 2" adapter and 1.25" connection for the 2x Meade TeleXtender to achieve 2400 mm FL.

Directly in front of the etalon is a 35 nm H-alpha filter. This also functions as an ITF, which was also present on the original PST but is missing here. This reduces the transmission in steps, primarily to save on the etalon and the expensive blocking filter.

This will soon be my solar telescope; hopefully, the sun will shine brightly this year!

Clear skies!

T