FIRST FIXED TELESCOPE FOR OBSERVATION

The first telescope that I used in the observatory was an 8" LX200 GPS mounted with an equatorial wedge. The main application was visual observation and first tests of astronomical photography. The pier is of homemade design, and manufactured in a local workshop.

LX200 TUBE ON EQ8 mount

The LX200 mount along with the equatorial wedge worked relatively well but had limitations of weight and movement with the camera and the spectrograph so I opted to disassemble the tube, attach a Lomandy fixation and install it in an EQ8. I found a web page with quite clear explanations of how to separate the LX200 tube from the fork:

 

 https://www.cabrillo.edu/~rnolthenius/observatory/NewObsBldg/LX200OTA/index.html

With this configuration, in addition to obtaining very good precision after Polar alignment , it allowed me to complement the LX200 with a TSED70Q refractor mounted in piggyback, besides the guiding tube on an ED80 of Lunático. The EQ8 that supports 50 Kg of weight does not even change by adding cameras and a spectrograph.

In this phase of the observatory, the LX200 I have always used a primary focus, without reducer, for deep sky, resulting with the optical train a 2200mm focal.

For photographs of the sun, moon and deep sky of wide field, I use the TSED70Q astrograph.

 

C11 on EQ8 mount

The next step was to move to a larger aperture tube, opting for the Celestron C11. During the start-up, I detected a problem with the guidance, so that the stars did not come out sufficiently rounded. Of course photographing a primary focus with a C11 with a focal length of around 3000mm is a challenge, but the guiding errors were too large to be pinned to the focal. Since I was used to working with the 8" LX200 with secondary mirror fixing screw, I came to the conclusion that the problem was due to the C11 lacking that screw, so I asked a professional to make the modification of the tube to incorporate it.

The photograph shows the modification to add two secondary mirror fixing screws. The modification worked correctly, but it did not solve the problem of rounding off the stars.

After many tests, I came to the conclusion that the problem was that I was using the guide camera mounted in parallel (piggyback) tube and bending issues (which I did not happen with the LX200) the rounding of the stars was affected.

The solution was to install the camera (a Startlight Xpress) in "off-axis" mode. The result was excellent, and the fixing screws, although they were not the initial problem, provide their extra stability and improve rounding.

Mount Ioptron CubePro

For applications that require portability, I use the Ioptron CubePro mount. It is a very light and portable Altazimuth mount, which incorporates GPS, which facilitates the start-up as it is not necessary to enter the position or the date and time. It has GOTO function that also includes the Sun, not available in all mounts, interesting in my case since I use it enough for observation and solar photography. The picture shows the frame with a TSED70Q (with sun filter and a Canon 60Da camera.