Takahashi Epsilon-130D 1.5x Extender

Product Overview

The Epsilon Extender 1.5x E-130D extends the Epsilon-130D astrograph's native 430mm f/3.3 to 650mm f/5.0, while carrying the same coma correction that makes the Epsilon series sharp to the edge of frame at prime focus. Seven elements in five groups do the work of both magnifying the image and holding coma in check at the same time.

Who It's For

This extender suits Epsilon-130D owners who want a longer working focal length for tighter deep-sky targets — galaxies, planetary nebulae, small clusters — without switching to a slower, narrower-field telescope. It keeps the fast, coma-corrected imaging the Epsilon series is built for, just at 650mm instead of 430mm.

Key Features & Design

• 7 elements in 5 groups: a full optical assembly, not a simple magnifying lens, that maintains coma correction at the extended focal length.
• 1.5x extension: takes the Epsilon-130D from 430mm f/3.3 to 650mm f/5.0.
• Φ44mm corrected image circle: diffraction-limited performance, about 2 microns at the center and up to 8 microns at the edge of a full-frame sensor.
• M60 input / M54 output threads: matches the Epsilon-130D's camera angle adjuster on one side and standard M54 camera adapters on the other.

Optical / Mechanical Design

The extender's seven-element, five-group design re-corrects coma at the longer focal length rather than simply magnifying the uncorrected image the way a basic Barlow would. Back focus is 56.2mm, the same figure the Epsilon-130D uses at prime focus, so an existing spacing setup carries over. See the Takahashi Back Focus Guide for the full chain.

Recommended Uses

Imaging smaller deep-sky targets — planetary nebulae, compact galaxies, globular clusters — that are undersized in the Epsilon-130D's native 430mm field; narrowband imaging where the extra focal length helps frame a target more tightly; general astrophotography where 650mm f/5.0 suits the target better than 430mm f/3.3.

Compatibility and Accessory Notes

The extender is specific to the Epsilon-130D — the Epsilon-160ED and Epsilon-180ED each use their own dedicated 1.5x extender, matched to their own thread sizes and back focus.

Good to Know Before You Order

Screw-in 2" filters aren't recommended with this extender, since Takahashi notes they can introduce reflections at this focal ratio — a filter wheel or camera-side filter mounting avoids the issue.

At 450g, it's light enough that it's the camera and filter wheel on the other end of the train, not the extender itself, that will drive your balance point.

Frequently Asked Questions

Is it difficult to set up?

No — it installs between the Epsilon-130D's camera angle adjuster and your camera on M60 and M54 threads, and the 56.2mm back focus matches the telescope's native prime-focus figure.

What is it best used for?

Imaging deep-sky targets that need more reach than the Epsilon-130D's native 430mm provides, while keeping the coma correction the Epsilon series is known for.

Does it work for visual observing?

It's built as an imaging accessory — the corrected image circle and mechanical interfaces are designed around camera sensors rather than eyepieces.

What else do I need with it?

Your camera's own T-ring or M54 adapter to complete the connection at the 56.2mm back focus figure.

Bottom Line

A coma-corrected 1.5x extender that takes the Epsilon-130D to 650mm at f/5.0 across a Φ44mm image circle, at the same 56.2mm back focus the telescope already uses at prime focus.