![]() ![]() Use of either ‘Field Flatteners’ or ‘Reducer/Flatteners’ (called reducers fromįocal length of the telescope essentially unchanged whilst the latter will The stellar images towards the edge of the field can be compensated for by the The Vixen VC200L and the Celestron ‘Edge HD’Ĭatadioptric telescopes employ additional lens elements mounted within the rearīaffle tube to, again, provide a flat field with ‘clean’ stellar images out toĬurvature of field and the effects of lens aberrations distorting With a singlet lens part way down the telescope tube to flatten the field. Teleskop Service 66 mm Quad astrograph which uses a triplet objective coupled Will very likely contain one or more additional elements such as in the Telescopes that aim to provide a flat field are called ‘astrographs’ and Sensors up to APS-C in size the captured images may not be materially affectedīut, with lower focal ratio telescopes and a full frame sensor, stars in the corners With telescopes of focal ratios greater than ~f/7 and The telescope the greater the problem as the curvature will be greater. Outer parts of a flat sensor, it will need to be slightly closer to the lens or As a result, in order to correctly focus the In the case of a refractor is the ‘nodal point’ of the objective lens. The image plane is actually the curved surface of a sphere whose centre Sharp image, standard telescopes are not. The focal length of the telescope become less and the size of the image sensorĭesigned to give a flat field so that all parts of the sensor will capture a Problem known a ‘Field Curvature’ can arise whose effects will be greater as When a digital camera is used for imaging with a telescope a ![]()
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