Amateur astronomers are happily rediscovering the excellence of orthoscopic eyepieces for observing the planets and the Moon: a simple optical formula, a reasonable cost and high-contrast images, only if materials used are of excellent quality and the construction is meticulous. Takahashi, renowned for these incomparable instruments and accessories, has taken this decision by offering its MC Abbe range, a technical evolution of its former Or range which already used the same formula.

The orthoscopic optical formula, originally developed by Ernst Abbe for the Zeiss company at the end of the 19th century, is simple. An overcorrected triplet of 3 glued field lenses is combined with a plano-convex eye lens, the convex side of which is almost in contact with the triplet. The basic characteristics of these eyepieces are good field flatness, absence of distortion and lack of angular magnification. The field, initially 30°, was increased to 40° with the evolution of the Zeiss formula in the 1930s, notably by the addition of lenses of better quality than the original crown and flint glasses. Takahashi opted for the latter approach; the cost is more important but the image obtained is beyond comparison.

The field of view of the MC Abbe is relatively small (44°) but the contrast is very high and the colour correction excellent. The images obtained are chiseled and of great finesse. These eyepieces are therefore reserved for lunar and planetary observation, as well as for the observation of double stars, for which the sharpness of the image is essential and the apparent field is secondary. The eye relief is shorter than on the vast majority of conventional eyepieces. It is therefore advisable to place the eye very close to the eye lens, which can make its use uncomfortable, especially for eyeglass wearers. Short rubber caps allow for correct positioning and prevent the entry of stray light. The 4 optical sides exposed to the air are treated with a multi-layer coating. Ghost reflections are virtually absent.

In combination with a good Barlow lens, the orthoscopic eyepiece also provides high magnification without the risk of contrast degradation.