Takahashi FC-100DC Fluorite Doublet APO f/7.4
Like the FS series, the FC series are apochromatic refractors with two-element fluorite lenses. The FC series have larger apertures and longer focal lengths than the FS series, and provide outstanding performance both for the visual observer and the digital imager. The FC series has its own dedicated set of reducers and flatteners, and is also able to use some of these accessories from the TOA series.
The FC-100D series consists of an apochromatic fluorite Steinheil doublet with a 100 mm objective diameter. Both telescopes in the series are 740 mm f/7.4 instruments. The front element uses an eco-glass for maximum light transmission, with a coated fluorite rear element for superb color correction.
The Takahashi FC-100DC model features a fixed dew shield and a 2.2 inch rack and pinion focuser. While a capable imaging instrument, it is designed with the visual observer in mind.
The FC-100DF is optically identical to the DC model, but features an enhanced 2.7 –inch focuser. It also features a shorter tube length that provides additional back focus for digital imaging applications. This added back focus allows use of the FC-35RD reducer, which converts the DF to an f/5.4 instrument.
The FC-100DL is a full-fledged long focal length apochromatic refractor from Takahashi. This is the same FC-100DL that was offered in limited quantities in previous years. With the exception of the focal length, it is identical to the FC-100DF.
The FC-100DZ is a fluorite doublet with a 100 mm aperture and an 800 mm focal length. In this doublet design, Takahashi has paired the fluorite element with a low dispersion glass having a high refractive index. This combination provides excellent optical performance across the entire visible spectrum with a Strehl ratio in excess of 97.6% across this range. In addition, to satisfy the increasing demands of today’s imaging system, this glass combination minimizes the blue halo sometimes present at shorter wavelengths. This halo intensity is reduced by about 50% when compared to the existing FC-100D.
Mechanically, the FC-100DZ has a tube diameter of 95 mm and a retractable dew shield. With the dew shield retracted and accessories removed, the total length is only 595 mm, easily carried on most commercial flights. The FC-100DZ utilizes the same focuser used on the FC-100DF and DL and weighs approximately 3.8 kg.