The price for high-quality refractors has fallen dramatically in recent years, and you can now purchase a 4-to-5-inch extra-low dispersion (ED) apochromatic (APO) telescope that's almost entirely free of the false color that plagues
achromats for a fraction of the cost commonly seen a decade ago.
In point of fact, there may well be phenomenal differences between, e.g.,
achromats and normally sighted people.
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.
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.
Achromats, the most inexpensive models, produce a bluish-purple halo of unfocused light around bright subjects such as the Moon and planets.
DayStar recommends using
achromats or apochomatic refractors without additional correcting elements near the focuser.
* Inexpensive refractors (ones called
achromats) are unable to focus all colors to the same point, which results in a halo of blue light around bright objects.
These include a pair of D&G Optical 5-inch f/30
achromats in oversized tubes that are intended primarily for solar observing.
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).