Male thread - M42X0.75; Female thread - M42X0.75; eliminates a range of focusing problems
The extension tube has a T2 interior thread and a T2 exterior thread for elegantly solving spacing problems in astrophotography.
Use this extension tube for getting the correct image scale or the exact spacing required for reducers or field flatteners
This device sits in 2 inch focuser in front of camera; small prism direct little light from telescope into separate tube where guide camera or crosshair eyepiece is attached; correct tracking errors which camera is exposing image for perfectly round star
For refractors scs maks and rc telescopes; off-axis guider only 24mm in overall length; robust yet light 5.45mm optical transmission full illumination; micro focusing especially smooth helical focusing with 0.05mm accuracy; 75mm of back focus