Celestron Right Angle Correct Image Finderscope RASA Tuning the etalon to each

Tuning the etalon to each side of the central wavelength is needed because local changes in atmospheric pressure change the refractive index of your local air mass

In his own words

4° Field of View

Built-in polar alignment program to polar align on any star in the sky

Small Refractors

Celestron Right Angle Correct Image Finderscope RASA Tuning the etalon to eachComfortable Right Angle Design: Keeps your neck and back at ease during long sessions Correct Image Optics: Produces natural viewsideal for both day and night use 9x Magnification with 50mm Aperture: Captures bright, sharp visuals with a 5 field of view Double Crosshair Reticle: Fine etched lines help you center targets precisely without obscuring stars Adjustable Eyepiece Orientation: Rotate for the perfect viewing angle Durable Bracket & Dovetail