Apochromatic refractor TS Optics 70/420 ED 1:10 OTA
Looking for a telescope that fits in a backpack but still delivers outstanding image quality? The TS Optics 70/420 ED refractor is exactly what you need. This apochromatic travel telescope with ED optics combines precise Japanese optics, well-thought-out mechanics and a surprisingly low weight - all in one elegant tube just 30 cm long.
Premium ED optics for sharp, color-accurate images
The heart of the telescope is a two-element apochromatic objective lens (ED doublet) made from high-quality, low-dispersion Ohara glass from Japan. This glass is highly valued among manufacturers of premium astronomical optics for its low dispersion index, which allows the objective to effectively suppress chromatic aberration - the unwanted color fringing that plagues ordinary achromatic refractors. The result is an image that is sharp, high-contrast and true-to-life across the entire visible spectrum. The lens surfaces are also coated with multi-layer anti-reflection coatings that maximize light transmission and minimize unwanted reflections and ghost images. The telescope therefore delivers excellent performance when observing planets, the Moon and fainter deep-sky objects.
Versatile f/6 focal ratio for planets and deep sky alike
A focal length of 420 mm combined with an objective diameter of 70 mm gives a focal ratio of f/6, which is a highly versatile parameter. The telescope can achieve magnifications of up to approximately 180x, at which planetary details become visible - Saturn's rings, Jupiter's cloud bands or the polar ice caps of Mars. At the same time, the shorter focal length and well-corrected field of view make this instrument well suited for observing large nebulae and star clusters with wide-field eyepieces. The f/6 focal ratio combined with apochromatic ED optics makes this telescope an excellent all-round companion for the night sky.
High-quality 2″ RAP focuser with dual-speed fine focusing
The newly developed 2″ RAP (rack and pinion) focuser is significantly above standard compared to the commonly used Crayford focusers. The rack and pinion mechanism provides firm, slip-free engagement and reliably holds even heavier photographic accessories - heavy eyepieces, diagonals or DSLR adapters with a camera attached. The dual-speed design (10:1 fine focusing) will be particularly appreciated by astrophotographers who need precise and reproducible focus. The focuser travel is 81 mm, and the back focus distance from the rear edge of the tube is 130 mm, which is sufficient for most photographic adapters and field correctors.
Compact and lightweight - the ideal travel telescope
The telescope weighs approximately 2 kg and measures just 30 cm, so it can easily be carried as hand luggage or in a backpack on a trip. The tube diameter is 76 mm, and the diameter of the dew shield is 88.5 mm. The telescope connects to mounts and photographic tripods via a flexible support plate with a standard photo tripod thread, providing great flexibility in the choice of mount - from simple alt-az tripods to equatorial mounts for astrophotography.
About the manufacturer
TS Optics (Teleskop-Service) is a German manufacturer and retailer of astronomical equipment with a long tradition and an excellent reputation in the European astronomical community. The company focuses on careful selection of optical components and in-house development of mechanical parts, including this RAP focuser. TS Optics products are popular among both beginners and experienced observers and astrophotographers, as they offer solid value for money and accessible customer service. The TS Optics 70/420 ED refractor is a convincing example of this - premium optics, practical mechanics and travel-friendly dimensions at an accessible price point.
Key specifications
| Parameter |
Value |
| Objective type |
ED doublet apochromat (Ohara glass) |
| Objective diameter |
70 mm |
| Focal length |
420 mm |
| Focal ratio |
f/6 |
| Maximum magnification |
approx. 180x |
| Focuser type |
RAP (rack and pinion), 2″, dual-speed 10:1 |
| Focuser travel |
81 mm |
| Back focus distance |
130 mm |
| Tube length |
approx. 30 cm |
| Tube diameter |
76 mm |
| Dew shield diameter |
88.5 mm |
| Weight |
approx. 2 kg |
| Mount connection |
Standard photo tripod thread (via support plate) |
Specifications
Type of telescope:
ED & Apochromats
Optical scheme:
Apochromat Doublet
Focal length:
420 mm
Aperture:
70 mm
Aperture ratio:
6
Resolving capacity:
1.65"
Limit value:
11 magnitude
Light gathering capacity:
100x
Max. useful magnification:
140x
Connection type:
2″
Mounting:
No mount
Recommended for:
Advanced, Experienced
Application area:
Astrophotography, Deep Sky observation, Planets observation
Package contents of "Apochromatic Refractor TS Optics 70/420 ED 1:10 OTA":
✅ 70 mm f6 ED refractor
✅ 2″ rack and pinion focuser
✅ Reduction adapter 2″ to 1.25″
Typical magnifications
The recommended magnification is highlighted in yellow.
D = telescope aperture in millimeters
