Four Elements 2x Apo-Barlow 1,25

Tecnosky 2x telecentric Barlow with 4 FMC-coated elements

Although this 2x Barlow doubles the focal length, the light rays in the optical system run parallel to the optical axis from the centre to the edge and are perpendicular to the focal plane. This flattens the image at the focal point and the aperture ratio is the same across the entire field (or with very slight differences). This feature is essential for the use of H-Alpha solar filters such as Daystar, Baader SunDancer, Solar Spectrum, etc., where the long focal ratio of f/20 or f/30 must be homogeneous across the entire etalon in order to obtain a detailed image of the Sun from the centre to the edges. The telecentric optical design of this Barlow lens also has the property of not increasing the magnification when something is placed between the Barlow and the eyepiece or planetary camera (e.g. a flip mirror, an ADC or a bino attachment).

Features:

• Double, apochromatic magnification
• Telecentric optical plate
• 4 FMC elements
• 31.8 mm eyepiece barrel
• Brass clamp