Planning a deep-sky mosaic

Start with the target size

Measure or look up the target’s approximate angular width and height. Then compare those dimensions with the field of view of your telescope and camera. The mosaic calculator gives you a starting panel count based on overlap.

Overlap is insurance

Too little overlap makes stitching fragile when framing or tracking changes. A little extra overlap costs exposure time, but it gives the software more matching stars and leaves room for cropping.

The right amount depends on your camera rotation, optical distortion, and how much final crop you can accept.

Plan the edges, not only the center

Dithering, imperfect pointing, gradients, and rejected frames all eat into the usable border. Keep the important part of the target away from the extreme edge of a panel whenever possible.