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Hall did not publicize his lens properly, and John Dollond (1706-1761), who prepared an achromatic lens in 1757, often gets the credit.
In an effort to replicate the views he had with Peltier's big refractor (but minus the color aberration inherent in an achromatic lens that size), Doug opted to make his Newtonian's spider with three curved vanes, thus eliminating the diffraction spikes produced by straight-vaned spiders.
5-inch (90-mm) achromatic lens with a focal length of 910 mm (f/10), this refractor is shipped with an altazimuth mount (which has dual-axis slow-motion controls) and an adjustable aluminum tripod.