D51F219 Diameter 51mm Refractive Green Film Telescope Achromatic Objective

Key Benefits

• 51mm diameter aperture collects sufficient light for detailed observation of bright celestial objects
• 219mm focal length provides a moderate focal ratio suitable for planetary and lunar imaging
• Green film coating minimizes ghosting and flare in bright optical environments
• Achromatic doublet design reduces chromatic aberration compared to single-element lenses
• K9 glass offers stable optical performance across temperature variations common in outdoor use

Application Scenarios

• Integration into a refracting telescope optical train for visual astronomy or imaging
• Use as a collimator in alignment systems for laser or optical bench setups
• Replacement part in a telescope that requires a 51mm achromatic objective
• Component in a custom optical system requiring a fixed focal length and large aperture
• Assembly into a portable or field-ready telescope for amateur astronomy

Who It Is For

• Amateur astronomers building or maintaining refracting telescopes
• Educational institutions teaching optical principles in physics or astronomy labs
• Engineering teams developing optical alignment or collimation systems
• Hobbyists and DIY telescope builders sourcing component-level optics
• Research labs requiring a stable, low-aberration lens for collimation or beam shaping

Problems It Solves

• A single-element lens would introduce significant chromatic aberration; the achromatic doublet corrects for red and blue light
• Uncoated glass surfaces cause light loss and internal reflections; the green film coating improves transmission
• Lack of a standardized aperture and focal length makes lens matching difficult; this lens has defined dimensions
• Field alignment systems require precise optics; this lens provides consistent focal length and centering
• DIY telescope builders need reliable component-level optics; this lens is supplied as a ready-to-use unit

Technical Features

• Achromatic doublet design reduces chromatic aberration in visible spectrum
• K9 optical glass provides high homogeneity and low thermal expansion
• Green film anti-reflective coating applied to both surfaces to increase transmission
• Focal length of 219mm with a 51mm diameter aperture for moderate focal ratio
• Supplied as a single unit with no mounting hardware, for integration into custom systems

Specifications

Specifications are taken from the AMADA product data for this item. Confirm critical dimensions with us in writing before ordering.

Customization Options

• Available as a standalone component for integration into custom optical systems
• No options for different coatings, focal lengths, or diameters provided in source text
• No mounting or adapter options included; must be sourced separately

Comparison With Other Options

Use Guide

• Handle the lens with clean gloves to avoid oil or dust on the coated surfaces
• Mount the lens in a stable cell with proper support to prevent stress on the elements
• Align the lens along the optical axis of the system to avoid coma or astigmatism
• Use in a controlled environment to minimize thermal drift and mechanical vibration
• Avoid exposure to high humidity or corrosive atmospheres to preserve coating integrity