Sun
The Sun is imaged in both, white light and in the spectral line of Hα. To obtain sharp images in white light, using a Baader filter (only 1/100000 of the light passes it) in front of the telescope aperture and very short exposures (1/4000 to 1/2000 seconds with the Canon EOS 1100Da) is appropriate. In the Hα line, use of the ZWO ASI 178MC is indispensible because of the low brightness produced by the Hα filter. So the technique is the same here as is being used for planetary photography. Hα
images of the Sun are taken with the Televue Pronto.
Image of the Sun in white light taken on July 20, 2024 at 11:30 CEST with Canon 1100 Da and Maksutov-Newton with Baader filter. Exposure 1/2000 s, ISO 200.
Sun in Hα, recorded on August 22, 2024, 14:26 CEST with Televue Pronto, f = 480 mm, D = 70 mm and Coronado Filter SolarMax H-Alpha-Etalon 60 mm BF10. Camera: ZWO ASI 178MC. Effective exposure time 2.92 s (5% out of 2411 frames with 20.4 ms each)
Image of the Sun in white light taken on July 20, 2024 at 12:45 CEST with Canon 1100 Da and Maksutov-Newton with Baader filter. Exposure 1/2000 s, ISO 100.
Sun in Hα, recorded on July 29, 2024, 13:30 CEST with Televue Pronto, f = 480 mm, D = 70 mm and Coronado Filter SolarMax H-Alpha-Etalon 60 mm BF10. Camera: ZWO ASI 178MC. Effective exposure time 2.14 s (5% out of 1765 frames with 20.4 ms each)
Image of the Sun in white light taken on July 7, 2024 at 11:47 CEST with Canon 1100 Da and Maksutov-Newton with Baader filter. Exposure 0.000625 s, ISO 100.
Sun in the light of Hα, taken on July 21, 2024 at 12:34 CEST with the ZWO ASI 178MC and Televue Pronto, using the Coronado Filter SolarMax H-Alpha-Etalon 60mm BF10. Effetive exposure time 6.7 s (15% from a total of 1765 Frames, 25.3 ms each). Quite a few prominences can be seen at the sun's rim. Beyond the rim, the image bears its original reddish colour for the sake of better visibility of the prominences, while the sun's surface is kept in black & white.
Above images with annotations.
Image of the sun taken on May 10, 2024, 12:43 CEST. There's a salient group of sun spots in the south-west. All of the dark cores, called umbra, are somewhat larger than the earth! Equipment: Maksutov-Newton telescope, 19 cm aperture, 1000 mm focal length, equipped with Baader solar aperture filter. Camera: Canon EOS 1100 Da, ISO 100, exposure 1/1600 sec.
Canon 1000Da with Maksutov-Newton, exposure 1/4000 seconds with ISO100.
Canon 1000Da with Maksutov-Newton, exposure 1/2000 seconds with ISO100.
Sun in the light of Hα. Image taken on May 15, 2019 at 16:21 CEST with ZWO ASI 178MC and Televue Pronto. Effective exposure time 3.5 seconds. Flares and prominences are clearly visible.
Sun in the light of Hα. Image taken on April 4, 2020 at 15:51 CEST with ZWO ASI 178MC and Televue Pronto. Effective exposure time 3.9 seconds. Also here, flares and, at the Sun's limb, prominences can be seen.
On the occasion of the partial solar eclipse on June 10, 2021 I have refurbished my 50 years old refractor. I had devised the projection screen at the time in such a way that I could superimpose a coordinate grid for any orientation of the sun, onto which I drew the sunspots with a sharp pencil. Still today, the projection works pretty well as can be seen here.