| 摘要 |
Provided is a color-image-reading Gaussian lens for reading out color images, color originals, or negative or positive films, which is suitably used at a low magnification of -1/2.5x to -1/1.25x, effectively corrects axial chromatic aberration in particular, and exhibits high performances in a wide wavelength range. A six-sheet Gaussian lens comprises, successively from an object side, two convex lenses, two concave lenses, and two convex lenses, while a stop is disposed between the two concave lenses. In particular, the following conditional expressions are satisfied: 0.10<D5/f<0.23 0.82<R5/|R6|<1.3 0.0012< SIGMA ( phi ix delta theta i)<0.0045 where phi is refracting power, and delta theta is anomalous dispersion. A glass material having anomalous dispersion is appropriately disposed, and an appropriate air gap is provided between the two concave lenses, thus making it possible to use a lens having a high refracting power, thereby effectively correcting axial chromatic aberration in particular and securing high performances in a wide wavelength range.
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