Magnification Ceiling & True Field Calculator
A box that shouts 525× is quoting an eyepiece, and eyepieces are cheap. Aperture is what caps the useful ceiling, and on most nights the atmosphere caps it lower still. Enter the clear aperture, the seeing and the sky you actually observe from for the magnification that buys real detail, the closest pair the instrument can split, the faintest star it will reach — and what any eyepiece you own delivers in it.
Clear diameter of the objective or primary mirror — the only figure that sets the ceiling.
Optional — the number shouted on the box.
What one eyepiece delivers
Magnification is a property of the pair, never of the telescope alone. Enter an eyepiece to see the power it gives in this instrument and how much sky is left in the view.
Printed on the barrel: 50–52° for a Plössl, 68° wide, 82° and up for ultra-wide.
The rest of the conversions, across both halves of the field, are in the tool bank and the guides.