Starfield - 0.8x Reducer and Field Flattener

Starfield 0.8x Reducer & Field Flattener — Faster Imaging, Wider Field, Sharper Edge Stars

The Starfield 0.8x Reducer doubles as a field flattener—a compact upgrade that widens your field of view, shortens exposure requirements, and improves star shape toward the edges of the frame. It’s designed for imagers using a DSLR or a dedicated astronomy camera.

At a Glance

• 0.8x reduction for a wider field and faster imaging
• Built-in field flattening for improved corner star shape
• Designed for refractors f/5.5 and longer with a 2" focuser
• 55mm back focus requirement (DSLR-friendly)
• M42 camera thread included + 48mm filter thread
• 38mm clear aperture (APS-C and smaller) / 42mm clear aperture with optional 48mm adapter

Compatibility

This reducer/flattener is designed to be used with any refractor that is f/5.5 and longer and has a 2" focuser. It requires 55mm of back focus.

Setup (Simple, DSLR-Friendly)

This accessory is designed around a standard 55mm back focus, making it a natural match for common DSLR imaging trains. No additional extension rings are required for typical DSLR spacing.

Required: A camera specific T-ring is required.

Manual (Recommended)

For full spacing guidance and imaging-train examples, use the official PDF manual: Starfield Reducer & Flattener Manual (PDF) .

M48 Adapter (Optional for Larger Sensors)

If you want an M48 camera-side interface (often preferred for larger sensors and wider imaging trains), use the optional adapter here:

View M48 Adapter

Technical Specifications

• Function: 0.8x focal reducer + field flattener
• Designed for: refractors f/5.5 and longer with 2" focusers
• Back focus: 55mm
• Clear aperture: 38mm (APS-C and smaller sensors)
• Clear aperture with optional adapter: 42mm
• Camera connection: M42 (T-thread), removable
• Filter thread: 48mm (for adding filters)
• Construction: multi-coated optics in a high-polish, hard-anodized aluminum body (all-metal)
• Requirement: standard 10mm T-ring required

FAQ

Is this both a reducer and a flattener?

Yes. It reduces focal length by 0.8x and also flattens the field for improved edge star performance.

What telescopes is it designed for?

Refractors f/5.5 and longer with a 2" focuser.

Do I really need 55mm back focus?

Yes—this reducer/flattener is designed around 55mm spacing. Use the manual link above if you want a spacing checklist.