NAKOH 60GT 測試報告 NAKOH 60GT Test Report (English at lower part of this post)

NAKOH是一個日本新望遠鏡品牌，星河科研社月前獲邀成為香港獨家代理，首款產品60GT折射鏡、0.65x減焦鏡及1.0x平場鏡，為市場上最高修正度的目視及攝星折射鏡之一，

早前進行星空測試，結果十分理想。

1. 這台鏡的機械造工十分好，如業界裡常叫的"built like a tank"，三片式APO鏡頭採用一片日本SD玻璃及一片ED玻璃，官網上的測試樣本修正度達97.% Strehl，已是業界裡傳奇品牌TMB-LZOS的水平了。接上頂級行星目鏡TMB Supermonocentric目鏡及TMB 1.8x ED barlow，織女星是純白沒色差的，木星雲帶及大紅斑對比度非一般折反射鏡能比，在香港近郊，受惠於這鏡的高對比度，一些主要深空天體形態也十分易見。當然，始終口徑只有60mm，很難做深入的目視觀測，但帶出去觀察或紀錄日月食等天象，則十分理想。

2. 接上Canon Ra全片幅天文相機，試用Bahtinov調焦版，瀟洒點用手動調焦，0.65x減焦鏡及1.0x平場鏡的表現，星點修正度及漸暈(像場邊緣失光)情況，一如官網上的參數般理想。這攝星系統完全能覆蓋全片幅相機。

可以從以下連結下載參考測試星場，RAW轉TIFF

60GT + 1.0x平場鏡 + Canon Ra全片幅相機

CR3 raw https://drive.google.com/file/d/1tmuKDokA8Y-thaGQZ-lEIP6ONo8FuzX3/view?usp=sharing

CR3 轉 TIFF調高一級曝光 https://drive.google.com/file/d/15Q9I96XabH4jhMBEhXbU1yIUsW1HiXAN/view?usp=sharing

60GT + 0.65x減焦鏡 + Canon Ra全片幅相機

CR3 raw https://drive.google.com/file/d/1gqFnjyoKLDZ3duG3ZIqS7LGZHq7X-HwD/view?usp=sharing

CR3 轉 TIFF調高一級曝光 https://drive.google.com/file/d/1gWlGWF7nbdUWVx5zSxWfRULfPWxg1fG4/view?usp=sharing

NAKOH 60GT Test Report

NAKOH is a new Japanese telescope brand. Galaxy Scientific Group was recently invited to become the exclusive distributor in Hong Kong. Its first product lineup includes the 60GT apochromatic refractor, a 0.65× focal reducer, and a 1.0× field flattener. The 60GT is positioned as one of the highest-corrected refractors on the market for both visual observation and astrophotography.

We conducted field tests under the night sky, and the results were very impressive.

1. Visual Performance

The mechanical construction of the 60GT is excellent - truly"built like a tank.” The triplet APO objective uses one Japanese SD glass element and one ED element. According to the manufacturer’s test sample data, the optical correction reaches 97% Strehl, which is on par with legendary brands such as TMB-LZOS. When paired with a premium planetary eyepiece (TMB Supermonocentric) and a TMB 1.8× ED Barlow, Vega appeared pure white with no detectable chromatic aberration. Jupiter's cloud bands and the Great Red Spot showed contrast levels that are difficult for typical catadioptric systems to match. Even under suburban Hong Kong skies, the high contrast of this telescope made the structure of several major deep-sky objects clearly visible. Of course, with an aperture of only 60mm, it is difficult to perform very indepth visual observations. However, it is an excellent choice for portable observing or for documenting astronomical events such as solar and lunar eclipses.

2. Astrophotography Performance

The telescope was tested with a Canon EOS Ra full-frame astronomy camera. Manual focus was achieved quickly and effortlessly using a Bahtinov mask. Both the 0.65× focal reducer and the 1.0× field flattener performed as specified. Star correction and vignetting control were consistent with the official specifications. The imaging system fully covers a full-frame sensor with excellent star quality across the field.

Sample test star-field images (RAW converted to TIFF) can be downloaded from the links below:

60GT + 1.0× Field Flattener + Canon Ra (Full Frame)

CR3 RAW https://drive.google.com/file/d/1tmuKDokA8Y-thaGQZ-lEIP6ONo8FuzX3/view?usp=sharing

CR3 converted to TIFF (+1 stop exposure) https://drive.google.com/file/d/15Q9I96XabH4jhMBEhXbU1yIUsW1HiXAN/view?usp=sharing

60GT + 0.65× Focal Reducer + Canon Ra (Full Frame)

CR3 RAW https://drive.google.com/file/d/1gqFnjyoKLDZ3duG3ZIqS7LGZHq7X-HwD/view?usp=sharing

CR3 converted to TIFF (+1 stop exposure) https://drive.google.com/file/d/1gWlGWF7nbdUWVx5zSxWfRULfPWxg1fG4/view?usp=sharing