▁with ▁high ▁magn ification ▁and ▁heavy ▁weight ▁usually ▁require ▁some ▁sort ▁of ▁mount ▁to ▁stabil ize ▁the ▁image . ▁A ▁magn ification ▁of ▁ 1 0 x ▁is ▁generally ▁considered ▁the ▁practical ▁limit ▁for ▁observation ▁with ▁hand h eld ▁bin oc ular s . ▁Bin oc ular s ▁more ▁powerful ▁than ▁ 1 5 × 7 0 ▁require ▁support ▁of ▁some ▁type . ▁ ▁Much ▁larger ▁bin oc ular s ▁have ▁been ▁made ▁by ▁amateur ▁teles cope ▁mak ers , ▁essentially ▁using ▁two ▁ref ract ing ▁or ▁reflect ing ▁astronom ical ▁teles cop es . ▁ ▁Of ▁particular ▁relev ance ▁for ▁low - light ▁and ▁astronom ical ▁view ing ▁is ▁the ▁ratio ▁between ▁magn ifying ▁power ▁and ▁objective ▁l ens ▁diameter . ▁A ▁lower ▁magn ification ▁facil it ates ▁a ▁larger ▁field ▁of ▁view ▁which ▁is ▁useful ▁in ▁view ing ▁the ▁Mil ky ▁Way ▁and ▁large ▁ne bul ous ▁objects ▁( re ferred ▁to ▁as ▁deep ▁sky ▁objects ) ▁such ▁as ▁the ▁ne b ula e ▁and ▁galaxies . ▁The ▁large ▁( typ ical ▁ 7   mm ▁using ▁ 7 x 5 0 ) ▁exit ▁pup il ▁[ object ive ▁( mm )/ power ] ▁of ▁these ▁devices ▁results ▁in ▁a ▁small ▁portion ▁of ▁the ▁gathered ▁light ▁not ▁being ▁us able ▁by ▁individuals ▁whose ▁pup ils ▁do ▁not ▁sufficiently ▁dil ate . ▁For ▁example , ▁the ▁pup ils ▁of ▁those ▁over ▁ 5 0 ▁rarely ▁dil ate ▁over ▁ 5   mm ▁wide . ▁The ▁large ▁exit ▁pup il ▁also ▁collect s