Guides

How the equipment actually works, and what the specification tables leave out.

• Which Dobsonian size: 6, 8, 10 or 12 inchWhat each rung buys in light — and costs in weight, storage and cool-down.
• How to collimate a telescopeWhat alignment is, how to tell it is out, and which tool is enough.
• What a Barlow lens actually doesIt doubles your eyepieces — and halves your exit pupil.