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Howdy,

I'm a soon-to-be amateur telescope maker, and I'd like some advice on mirror sizing.

I'm planning a pretty standard Newtonian reflector on a Dobsonian mount. Truss tubes, most likely, so I can fit it in the trunk of my car. I know a larger aperture will give me better light-gathering ability, but until I've proven my dedication to the hobby my significant other's tolerance of it will probably be inversely proportional to telescope size and cost. So, what's the smallest I can get away with and still resolve some planetary detail and pick out a few decent galaxies/nebulae?

Many thanks!

edited Oct 21 at 13:25

Adam Hollidge♦♦
165●8

asked Oct 19 at 3:01

First Light
21●1

alintolea · Answer 1 · 2009-10-19 03:14:25Z UTC

If you're going to go truss tube for compactness reasons, a "fits in any car and still shows you stuff" is probably a 10" f:5. However, a 12" f:5 is not much larger and can and will show you more while not having that much of a larger footprint and it won't cost that much more to build.

peterloron · Answer 2 · 2009-12-29 02:16:58Z UTC

Go get yourself a copy of "Star Ware" by Harrington. It covers a lot of information about what, where, and why of telescopes and observing. Once you have a better handle on that, you can make an informed choice about what to build.

Having said that, I'd go a bit smaller than alintolea and recommend nothing bigger than an 8". Harrington's book will explain why better than I can.

Star Ware @ Amazon

HRJ · Answer 3 · 2010-04-03 09:00:20Z UTC

I would recommend an 8" mirror.

There are three factors you need to consider:

portability,
light gathering power and
ease of construction (of mirror and mount)

The last point is important!

For a first time ATM, an 8" mirror proves a considerable challenge. Anything beyond that will require a lot of time & effort and, preferably, guidance from an expert.

Building my first telescope. Mirror size recommendations?

3 Answers