For astrophotographers, backfocus isn’t just a number — it’s the key to capturing pinpoint stars and crisp images. Cameras like DSLRs or dedicated astro cameras need their sensors positioned exactly at the telescope’s focal plane.
Use the correct T-ring and adapters designed for your camera and telescope. Remember to factor in any filters, off-axis guiders, or focal reducers that add optical path length.
Measure the total length of your imaging train to ensure it matches the manufacturer’s backfocus specification. Test your setup by capturing star images and adjusting spacers until stars appear as sharp dots without coma or vignetting.
