Like all fast achromats
, the Infinity 90 shows violet halos around the Moon and planets, but the planetary views are otherwise quite attractive and detailed.
Lower-powered microscope objectives can be of moderate quality, such as achromats
, as lower magnifications are typically used.
The sun blinds people with achromatopsia, known as achromats
, when they are outside, and some people are so sensitive to light that they are even uncomfortable indoors in a normally lit room.
Lenses are limited by the inherent diffraction efficiency of the aspheric surface, so they yield a lower overall transmission than comparable aspherized achromats
DayStar recommends using achromats
or apochomatic refractors without additional correcting elements near the focuser.
, the most inexpensive models, produce a bluish-purple halo of unfocused light around bright subjects such as the Moon and planets.
Company specializes in custom manufacturing of precision lenses, prisms, achromats
, windows, mirrors, and filters.
These include a pair of D&G Optical 5-inch f/30 achromats
in oversized tubes that are intended primarily for solar observing.
Fast, short-tube achromats
are very compact (so are nice travel scopes) and are best for wide-field deep-sky viewing.
That $20 telescope fired her imagination, just as many other lowly 50-mm achromats
have done for others (I still fondly remember my first 50-mm Tasco).
eliminate the worst of the false color, but they still show violet fringes around bright objects.
Thankfully, you don't need an expensive apochromatic objective lens either, since the chromatic aberration inherent in short-focus achromats
isn't noticeable at the low magnifications typical of RFTs.