History of Solar Telescopes

Venus Transit, ETX-60AT June 6, 2012

History of Solar Telescopes at Otis Astro Imaging

The history of solar telescopes began in 1965 and has continued ever since. Otis Astro Imaging now has these telescopes inside solar observatories doing their work and studies. 

Above: The first solar telescope is a 4.25-inch f/11 reflector from Edmund Co. which is fitted with a purchased accessory glass solar filter, possibly purchased from the former Kenneth Novak and Company. Numerous photos are taken of sunspots and a solar eclipse.

Left: the 2nd solar telescope is a low cost bare bones Celestron 2.99-inch FirstScope f/3.95 Newtonian reflector on a tiny Dob mount - The telescope is fast to setup and lightweight to carry around and transport. It has a focal length of 300mm (12-inches). It was purchased at a toy store in Beijing, China. For solar use, the telescope needs an accessory solar filter film mounted over the front of the telescope tube for best results (sold separately). The grab n go portability and no setup time makes this telescope a first choice for ease of use. General land & Moon images are taken by holding the mobile phone over the eyepiece for eyepiece projection and selecting the best result.

Left: The third sun telescope is the Meade f/5.6 ETX-60AT Refractor is used for solar transits and for studying sunspots. One special study captured the disk of Venus in front of the sun during the June transit and is examining the atmosphere fringes out from the planetary disk and any Venusian surface features.

The 60mm telescope is a precision achromatic refractor on a battery powered GOTO mount. The telescope has very high resolution and is a very good performer. The telescope has a flip mirror, with positions for the eyepiece or straight-through for astro imaging.

Left: 4.5-inch f/4 Orion Starblast is German equatorially mounted and outfitted with an extra accessory electronic sidereal drive and a Chinese solar filter made with Baader solar film. The filter is shared with a second Orion Starblast on a Dob mount.

The second telescope is a Celestron 2.99-inch reflector on a Dobsonian mount that uses solar projection in conjunction with a high concentration of air pollution, in Beijing China. Images were published at the Parallax Forum by Humanoido.

Left: The fifth telescope is the Orion StarBlast 4.5-inch f/4 RFT reflector with a grab and go Dob mount. This telescope shares an identical solar filter with the first equatorial mounted Orion Starblast telescope.

The telescopes have different purposes - one is more ideal for the static observatory and the other is perfect for a portable observatory with the grab and go telescope.

Left: Transit of Venus June 6, 2012 through the 1.6-inch Meade ETX-60AT f/5.6 achromatic refractor.

The third telescope is a Meade ETX60AT (2.6-inch) f/5.8 achromatic refractor used to observe the transit of Venus from a skyscraper rooftop.

https://humanoidolabs.blogspot.com/2012/06/venus-transit-2012.html

A solar sunspot study was made in full color on the previous day of June 5th, 2012 at 4:43:48 pm local time, using ISO125 at 1/400 F5.6 to identify the position of solar spots, test the imaging results, obtain satisfactory full disk image size and resolution, position enlarged disc views, and lock down the setup and imaging procedures. (see June 5th

photo). 

Left: June 6th sunspots photo'd with the Meade ETX-60AT achromatic refractor, during the transit. Approximately nine sunspot groupings are seen. All photos by Otis.

The fourth and fifth telescopes are Orion StarBlast 4.5-inch f/4 with a driven equatorial mount and a grab and go Dob mount. These share a solar filter obtained from China.

Telescope six is a Celestron Nexstar 6SE f/10 on a goto mount that fits the Celestron solar filter.

The newest addition is telescope seven, the famous Acuter Maksutov-Cassegrain Catadioptric 60mm (2.4-inch) f/12.5 with its own solar filter. The solar filter is an extra purchase.

Seen at left, the filter form fits tight onto the front of the Acuter 60mm Maksutov-Cassegrain telescope's OTA. The filter assembly contains a safe projection sun finder molded into the carrier and offset to the side of the filter.

This system is very convenient to carry around (the OTA weighs only one pound) and it has a setup time of only a few minutes. It can compete with finding and utilizing the holes in the clouds to quickly capture views of the sun and sunspots within their 20-minute openings. The setup is ideal for transits and solar eclipses. Others have used the telescope for attaching H-Alpha filters for viewing of the chromosphere, solar prominences etc.

Solar Telescopes

1) Edmund 4.25-inch f/11 reflector

2) Celestron 2.99-inch f/3.95 FirstScope on a tiny Dob mount

3) Meade f/5.6 ETX-60AT Achromatic Refractor

4) 4.5-inch f/4 Orion Starblast Equatorially Mounted with Drive

5) 4.5-inch f/4 Orion Starblast Dob Mounted

6) Celestron Nexstar 6SE f/10 GOTO Mounted

7) Acuter Maksutov-Cassegrain Catadioptric 60mm (2.4-inch) f/12.5