Such lenses are used only in toy microscopes. Achromatic lenses correct for this by using two or more elements. Achromatic lenses vary in quality and are adequate for most purposes. Better correction is achieved by apochromatic lenses. It is capable of either dry or oil-immersion use.
Objectives are expensive.
It should be easy to see why. Since the eye can compensate for the very slight aberration left by an achromatic lens, apochromats are normally needed only for very critical applications and for photography. Achromatic and apochromatic lenses will not perfectly focus the specimen onto a flat visual plane, and a planachromatic lens corrects for this. Since the eye, when focusing over the visual field, corrects for the slightly non-flat image, planachromats are only needed for very critical photomicrography and at low powers, where the field of view is wider. The very best objectives are planapochromatic, that is, they have optimal color correction and a flat field.