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What is Advanced Coma Free?
The Meade ACF-optical system has a great advantage when compared to conventional optics: it doesn´t have coma. Coma is a optical aberration that affects stars outside the middle of the image. The starlight is spread to form a cometlike tail. Meade Advanced Coma Free optics don´t have this aberration. You can see the difference with each look through the telescope: small round stars up to the edge of the field of view. The higher concentration of starlight also rises the contrast of the image and fainter stars get visible. If it is visual observing, or astrophotography: the Advanced Coma Free optics from Meade Instruments deliver the superior images when compared with conventional serial telescopes. Meade ACF telescopes provide a image quality that was in the past only available by Ritchey-Chretien telescopes and other exotic systems. Those telescope have prices that are much higher than the Meade ACF optics.

SC: Fig.1: Fig.2: Fig.3:

Tech Talk: Why is Meade ACF optics better than conventional systems? A telescope concentrates the starlight into a Airy disc, see upper images . The more light an airy disc contains, the brighter it appears. The airy disc is surrounded by diffraction rings, that are very faint in an ideal telescope. You can see the first and brightest ring in the upper images. If we compare two telescopes with the same aperture, the telescope that concentrates more starlight into the airy disc will show brighter stars. However, in conventional telescopes for amateur astronomers this ideal light concentration only happens on one point in the field of view: the middle. Outside the middle the stars get deformed because optical aberrations occur. The most disturbing of those aberrations is coma. When a optical system has coma, the starlight gets spread into a cometlike tail, see the image in the middle left. This not only happens at the very edge of the field: the image shows a star that is only 5mm from the middle of the field of view. If the distance to the middle gets larger, so does coma, see the picture below left. The starlight gets spread over a large area. For comparison see the images that a Meade Advanced Coma Free telescope provides: small round stars that are losing only very little contrast on the very edge of the field.

ACF: Fig.1: Fig.2: Fig.3:

Note: Changes and errors may have occured during the making of this pages. The star patterns were calculated on the basis of ray trace data for 8" telescopes by using the free program Abberator. Real telescope images may differ from the shown one. The copyright of the astrophoto belongs to Bernd Koch. Due to the limited dynamic range of computer monitors the images had to be processed..This happened with the same settings for all respective images.

MEADE und M-Logo sind eingetragene Warenzeichen der Meade Instruments Corporation. ® USA und ausgewählte Länder. © 2008 Meade Instruments Corp. Alle Rechte vorbehalten. Änderungen und Irrtümer vorbehalten. Hergestellt unter den US-Patenten Nr. 6.304.376 und 6.392.799; weitere Patente in den USA und anderen Ländern angemeldet.