Field Flattener f/5 to f/7 Aperture_1. 21mm - 34mm precise tracking of celestial or

precise tracking of celestial or terrestrial targets

and general outdoor observation

The deep red illumination is continuously variable to provide the desired brightness

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Field Flattener f/5 to f/7 Aperture_1. 21mm - 34mm precise tracking of celestial orWhen doing astrophotography with refractor type telescopes, the faster the focal ratio the more field curvature becomes a problem. Field curvature will appear in the corners of astrophotographs, making the stars smear perpendicular to the axis of the image. This is called coma coma is Latin for comet, because the stars look like comets. The more the curvature, the closer to the center the coma appears. The larger the sensor, the worse the coma.