Case study: Using an achromatic objective as its own focal reducer

Commercial telescopes are more often than not provided with a focal reducer, which enables the customer to use the telescope also for astrophotography. Here I introduce two cases where a second objective unit identical to the primary unit serves as the focal reducer to the first unit which reduces not only focal length but also design and manufacturing costs.

Published 6.9.2018 by Jani Achrén, who would love to tell you more here.

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A folded Cassegrain telescope saves up space and a whole world of troubles

A folded Cassegrain type telescope objective is nothing new, but given present advancements in optical manufacturing, a worth reconsidering.

Cutting the optical tube length in half with a flat mirror and moving the secondary to the center of primary mirror hole is not a new idea and does nothing to help manufacture and assembly. Instead making a single mirror with a binary surface, i.e. one radius at inner zone and another in outer zone, a whole world of manufacture and assembly problems can be avoided. Assembly problems would eliminate themselves, and manufacturing would get easier by making traditional manufacturing near impossible and forcing more advanced techniques.

Published 30.10.2016 by Jani Achrén, who explains more here.

New or improved for commercial telescope optics?

Commercial astronomical telescope optics development has followed a straight tangent for decades now. Focal lengths have shortened while image sizes have grown. Refractive telescopes houses five or even six lenses, making them more and more like over-sized camera optics, driving up manufacturing costs fast. Producing more and more expensive and generic products for smaller and smaller range of enthusiasts does not pay back development.

Published 20.3.2015 by Jani Achrén. More about the topic here.

Fast F/1 reflective Maksutov microscope objective

20150206_2Originally suggested by Maksutov, a Maksutov microscope objective (or eyepiece) is a reverse Gregorian type reflective objective. It has high numerical aperture and has corrected spherical, coma and color aberrations. It requires a field flattener to correct the field curvature, but for on-axis observations, it has a long working distance and short total track.

Originally published 6.2.2015 by Jani Achrén. Read the rest from here.