26 Inch Cassegrain telescope

Dear Star Lovers,

After more than 2 years of struggling, the 26 inch telescope is officially declared completed today, on the day of annual Open Day of our school.

The whole telescope will be displayed on the roof of Queen’s College on Saturday (30 Jan 2016) and you are cordially invited to come and have a glance and offer comments on this big telescope. According to weather forecast the weather will be fine on Saturday.

At its Cassegrain focus the telescope offers a focal length of 260 inches at f/10. The telescope is very long, has a length of about 11 feet, which makes it an impossibility for a portable instrument. It will stay forever on roof of QC to promote astronomy among students, and any persons who are interested.

The total weight of the instrument is over 100 kg, the giant weight is a must for its stability at our roof, since our school is in constant vibration originating from the next door MTR tunnels.

Below gives a brief final technical specification of this newly finished telescope:-

Aperture :- 26 inches
Type :- Naysmith Cassegrain
Zenith eyepiece height :- about 5 feet, a junior form student’s height.
Secondary mirror diameter :- 10 inches.
Secondary blockage :- 38%, a little bit high. ( C8 is 33%)
Mounting :- alt-azm mount with ServoCAT GOTO and tracking + Argo Navis navigator.
Total weight :- > 100 kg.
Why we make it? :- to experiment if we can see DSO at center of city.

Our student are of course very pleased with what they have accomplished. Please come and share the enjoyment with us.

Best regards
Chan Yuk Lun
30 January 2016

The 26 inch Cassegrain, with GOTO and DSC navigation system. It is no more a Dobsonian but rather an ...