How to use the SV199 1.25” ADC Atmospheric Dispersion Corrector

The ADC Atmospheric Dispersion Corrector is a prism that can correct atmospheric dispersion by incorporating two rotating wedge prisms. Atmospheric dispersion is a phenomenon in which the image of a low-altitude planet becomes blurred due to the influence of the atmosphere. You can rotate the wedge prism of the ADC prism to adjust it to the proper angle and correct for color bleeding. Today I will introduce to you how to use the SV199 1.25”ADC Atmospheric Dispersion Corrector.

First, let me introduce the specifications of the product.

Model: SV199
Surface Accuracy: 1/4λ
Telescope side: 1.25" barrel
Optical aperture: 24mm 
Prism: BK7
Lateral surface: Blackened for improved contrast
Coatings: Anti-Reflective Brad-Band (300nm-700nm)
Deviation Angle: 4.5 degree
Required back-focus: 56.57nm
Net Weight: 167g

The amount of blur depends on the altitude of the planet. Planets closer to the zenith have less color fringing. Planets on the horizon will cause more color bleeding. The ADC rotates the built-in prism to an appropriate position to compensate for this blurring and achieve the effect of aligning the imaging positions of each wavelength.

First, set the two prism rotation levers and the mark ring fixing screw in a straight line as shown in the figure below.

Connect the ADC Prism to the telescope so that the bubble of the level bubble on the fiducial ring is centered.

The position where the two levers are aligned is the position where the amount of correction is 0. Connect the eyepiece and gradually rotate the two levers in opposite directions. Fix it at the position where the color fringing that appears above and below the planet is minimized.

Please refer to the surrounding scale and rotate both levers by the same amount little by little.

If you have any questions about the product, please feel free to contact us.