Airy Disk Flat-field Adapter for 60mm, APS-C

1x-Flat Field for sharper stars all to way to the edge. Specifically made for the 60mm APO. Screws on to the M63x1-Thread. The spot diagrams show that all colors are well corrected up to APS-C. ♦ 1x factor ♦ 55 mm to 60 mm back distance - fine tune in 0.05 mm Increments - from the M48x0.75-thread. Magnification: 1x Connecting thread: M54*0.75 Camera thread: M48*0.75 Image circle: 44.4mm Min back focus: 55 mm Max back focus: 70 mm Weight: 0.52 lbs