Takahashi Epsilon-130D (E-130D)
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.
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.
Specifications from Takahashi
Focal ratio: 3.3
Effective focal length: 430mm
Image circle: 44mm
Back focus: 56mm
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.
|A Pelican iM2600 Storm case provides a tight fitting strong, protective transport and storage case for the E-130D.|