Takahashi Epsilon-130D (E-130D)
First Light

This is a running summary of my experience with the Takahashi Epsilon-130D ( E-130D) hyperboloid flat-field astrograph (130mm f/3.3) that became widely available in the USA from Takahashi in December, 2013.

First light image with the E-130D. With a nearly full moon on December 18, the first imaging could only be done in narrow band (5nm) hydrogen alpha. IC434, the Horsehead nebula (Bernard 33) and the Flame nebula (NGC 2024) stand out with Alnitak in wide field nebulosity that is part of the Orion molecular cloud complex. This is a nearly full field frame taken with the STL-11000M (5 x 15 minute exposures, image acquistion with MaximDL 5 and processing with PixInsight and Photoshop CS6.)

Takahashi Epsilon-130D with SBIG STL-11000M mounted on Astro-Physics 900 GTO. A custom machined adapter plate attaches the Takahashi rings to the Losmandy DUP plate. An Orion red-dot finder is attached to the finder base. A Tahahashi TCD0012STL adapter connects the E-130D to the STL-11000M.	A modified Losmandy DUP plate and modified DR-108 ring set facilitate side-by-side mounting of the E-130D with a small guidescope (Orion Short Tube 80mm f/5).

Data / Observations Summary

• The E-130D has the same back focus (56mm) and accepts the same adapters as the E-180 and E-160.
• The heavy duty rack and pinion focuser easily handles the load of a heavy camera (e.g., STL-11000M) with no flexure
• Accurate manual focus is simple with a Bahtinov mask
• The field is flat as advertised and produces pin-point star images to the edge of the field
• Light fall off from the center of the field and vignetting are substantial, but are correctable with flat field calibration (see below)
• LRGB imaging will be completed in late December, 2013 and more information will follow.
  
Flat field image (36x24mm sensor) showing light drop-off and vignetting with the E-130 and the STL-11000M

Specifications from Takahashi
Aperture: 130mm
Focal ratio: 3.3
Effective focal length: 430mm
Image circle: 44mm
Back focus: 56mm

 

Collimation Procedure
The brand new E-130D I purchased had a well aligned secondary mirror upon receipt. However, the primary mirror required slight adjustment to be collimated.

Click here to download the Takahashi Epsilon-130D Manual pdf

The manual initially distributed with the E-130D has a convoluted description of the collimation procedure that makes reference to schematics and descriptions for collimating the Epsilon-180 which has different primary mirror adjustment system. Procedures for aligning the secondary mirror with the Takahashi collimating tube and collimating eyepiece are simple and reasonably organized in the manual.
Procedures for collimating the primary mirror are incomplete and inaccurately described in the manual initially distributed. See the following schematic and image for reference.

 

Schematic of primary mirror cell and adjusting screws from Takahashi manual

Detail of primary mirror adjusting screw and locking screws

To collimate the primary mirror, follow the general procedure described in the manual. However, to adjust the primary mirror using the three (n=3) primary mirror adjusting screws, the two 2.5mm locking screws and the 2mm locking screw should be loosened slightly first before each 4mm socket head cap screws is moved. After the primary mirror is aligned, carefully tighten the 2.5mm locking screws and the 2mm locking screw. Hopefully, Takahashi will update the manual with an accurate and clearer description of the collimation procedure. Once learned, the collimation procedure is reasonably simple to do. It is worth purchasing the Takahashi collimating tube and eyepiece to be sure the astrograph is optimally aligned prior to using it for astrophotography.

Storage case

In Progress

• Waiting for dark, clear skies to perform LRGB astrophotography
• Working on installation of Robofocus for autofocus and automated operation



Review Index

posted 20 December 2013. Updated 21 December 2013
© 2013, William L. Castleman