Astronomy Notes

Before anything starts, I want to explain AA. AA is my own abbreviation, it’s Amateur Astronomer in full.

What’s the common requirement of an AA’s scope? Unless you are a serious AA with deep pocket, you won’t have an observatory that allows you to mount a gigantic telescope inside. Some AA travels to the dark site with his scope or just move his scope from his house to the backyard. It can’t be too heavy. So, portability comes into one of the major considerations. We want to get the largest aperture within the portability.

8″ SCT has it all. For example, my fork mounted LX90 has an aperture of 203.2mm, 2000mm focal length and weights about 24kg. I can carry it around easily. (Not for a marathorn though)

Left: 8″ LX90 of Edwin Kats from Netherlands.

Talking about visual observing, almost every object can be framed inside the FOV of 8″ f/10 SCT with the 40mm eyepiece attached. The field of view of this combination is 1º (Formula of TFOV). If it can’t, just use a FR0.63. True, you may say, “Why not I just get an 8″ Newtonian?”. It’s about portability. An 8″ SCT is better than an 8″ Newtonian in this.

You have limited budget. You want to do wide field astrophotography without buying a large refractor. You want that aperture. Yes, 8″ SCT with focal reducer will work again. Imaging with a FR0.33 will make the focal length reduce to 660mm. Now, you have a wide FOV and good light gathering power. Now, your exposure can be 4 times shorter to get almost the same result of a 110mm f/6 refractor. (Forget about coma and abberration here)

What about planetary observing and imaging? Don’t forget the 8″ SCT has a long focal length and mid-large aperture. It’s definitely good at planetary.

In conclution, an 8″ SCT is an all rounder.

• There is an alternative to move and mount your biggier telescope without much effort but what I discuss here, take budget into consideration too.
• You may understand the abbreviations by visiting this page