Out of the box they almost never do. It is the commonest reason a first evening ends with nothing found, and it takes ten minutes to fix, in daylight, before your first night.
The short answer
- Pick a fixed, sharp, distant object: the top of a telegraph pole, an aerial, the cross on a spire. At least a hundred metres away, ideally several hundred.
- Fit the eyepiece that magnifies least (the largest number in millimetres) and centre the object in the telescope. Lock or tighten the movements.
- Without touching the telescope, turn the finder bracket's screws until the crosshair or red dot sits exactly on the object.
- Check again in the telescope, then repeat with a higher-power eyepiece to refine.
Why in daylight, not on a star
At night everything moves: the Earth turns, the star drifts out of the telescope's field while you adjust the finder, and you no longer know which of the two you have just knocked out. A pole does not move. And in daylight you can see what you are doing: you find the object in the telescope by sighting along the tube, which is almost impossible at night with a misaligned finder.
The further away the object, the better: at twenty metres the finder and the telescope, a few centimetres apart on the tube, do not quite aim at the same point. At a few hundred metres that offset no longer matters.
Step by step
- Set the telescope up outside, or at an open window (the glass of a closed one blurs the view).
- Lowest-power eyepiece in. Aim at the object by sighting along the tube, then find it in the eyepiece. Focus.
- Centre it, then lock the telescope: clamps on a mount, or simply stop touching it on a Dobsonian.
- Look through the finder. With an optical finder the image is often upside down: that is normal. Turn the bracket's adjustment screws one at a time, in small steps, until the crosshair lands on the object.
- Check in the telescope that the object has not moved. If it has, re-centre and start again.
- Switch to a higher-power eyepiece, re-centre in the telescope, refine the finder. That is what makes the alignment precise.
- In the evening, check on a bright star or the Moon: centre it in the finder, and it should be in the telescope's field.
Red-dot sight or optical finder
A red-dot sight does not magnify: it projects a dot onto the sky as you see it with the naked eye, which makes it very intuitive for a beginner. An optical finder (a small scope of 30 to 50 mm) shows fainter stars, but upside down and in a narrow field. Both are aligned the same way.
Two sights, from the cheapest to the classic
Red-dot sight Omegon · LED red-dot finder
The cheapest replacement for a small straight-through finder. Check that it fits your telescope's finder shoe before you order.
Where to buy
1 of these 1 links earn us a commission, marked above. Sorted by price, never by what pays. How this site is funded.
Telrad, the ring sight Telrad · Telrad finder with base
Projects three rings onto the sky instead of a dot, which helps you judge distances between stars; some atlases print its rings. Bulkier, and its base sticks onto the tube.
Where to buy
1 of these 1 links earn us a commission, marked above. Sorted by price, never by what pays. How this site is funded.
Questions people ask
How do you align a telescope finder?In daylight, on a fixed, distant object.
Centre it in the telescope with the lowest-power eyepiece, lock the telescope, then adjust the finder's screws until its crosshair or red dot sits on the object. Refine with a higher-power eyepiece.
Why can't I find anything in my telescope?Most often because the finder is not aligned with the telescope.
The second cause is an eyepiece that magnifies too much: always start with the one that magnifies least, which has the widest field.
Can you align a finder at night?You can, on a bright star or the Moon, but it is much harder: the star drifts out of the field while you adjust.
Do the bulk of it in daylight and check in the evening.
My finder shows the image upside down. Is that normal?Yes, for most optical finders.
It makes no difference to the alignment. A red-dot sight flips nothing, since you look at the sky through it.
Is aligning a finder in daylight dangerous?Only if the Sun can come into view.
Keep your back to the Sun, cap the finder and the telescope while moving them, and watch children: a glance at the Sun through an instrument causes permanent damage.
Method and changes
What this page rests on and when it changed, computed from the catalogue — no date below is typed by hand. There is no price history yet, so this log says what was read and when, never whether it went up or down.
- First published
One price per model: the cheapest observed offer, with its date. Models are ordered by that price, never by what a link pays. How we choose.
Written and maintained by the person behind About.