Designed specifically for SV503 70mm, 80mm, and 102mm f/7 ED Refractor.

The field flattener corrects the inherent spherical aberration of curved lenses which causes distortion at the edges of the field of view.

The default back focus is 55mm. 70mm telescope's front end is an M54x0.75 socket to connect to the main lens.

• 0.5x focal reducer cuts the telescopes focal length in 0.5 times of original's to get a wider field of view
• Fully anti-reflection coatings on all air-glass surfaces for increased contrast
• The focal reducer is great for visual use for a bigger FOV and is indispensable when CCD imaging
• Fully metal structure design;both the ends of the interface part is 28.5x0.6 thread
• Directly connect the interface to the eyepiece;there is a very good performance in both visual and photography