Asked by John Green
The presence of a counterbalance on a telescope is governed by its size. Some telescopes are small enough and arranged in such a way that means they do not require them: effectively, they’re intrinsically balanced.
Typically larger telescopes have larger optics systems. These are usually weighty pieces of glass making up the lenses and mirrors. In larger systems these may be off-centre or just too much for the bracket locking systems to hold in a stable position. To help compensate for this counterbalances are required. Counterbalances help to stabilise the telescope to allow for clear viewing. Generally the larger the telescope, the heavier the counterbalance will be.
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