ZWO 30 mm f/5 Mini Guide Scope - 30F5 32 mm Eyepieces Filter Thickness: 2mm+/-0

Filter Thickness:   2mm+/-0

Astro-imaging using intermediary lens systems can require a precision back focus to the image plane so as to obtain the best color and eliminate any field curvature

Commonly used in iPhone X

In this case

ZWO 30 mm f/5 Mini Guide Scope - 30F5 32 mm Eyepieces Filter Thickness: 2mm+/-0Features of the the ZWO 30F5 Mini Guide Scope include: The upgraded high precision focus knob with positioning screws ensure no focus shift. Extended focal length for sharper guide stars. Upgraded APO optical system with ED glass reduces chromatic aberration of stars Easy installation with a quick release dovetail plate for rapid connection or removal Accepts an optional back for use visually, an imaging camera, or a guide camera for guiding. The