Ina tomo koe ki tētahi toa mōhiti ka ngana ki te hoko i tētahi takirua mōhiti, he maha ngā momo kōwhiringa mōhiti kei a koe i runga i te whakahaunga a tō tākuta. Engari he maha ngā tāngata e pōhēhē ana ki ngā kupu "kotahi te tirohanga", "rua te tirohanga" me te "whakamua". E pā ana ēnei kupu ki te hoahoa o ngā mōhiti i roto i ō mōhiti. Engari ki te kore koe e tino mōhio ki te momo mōhiti e hiahiatia ana e tō whakahaunga, anei tētahi tirohanga poto hei āwhina i a koe ki te tīmata.
1. He aha ngā karāhe tirohanga kotahi?
Ko te karāhe tirohanga kotahi he karāhe e pupuri ana i te kotahi whakahaunga. Ka whakamahia tēnei momo karāhe mō ngā whakahaunga mō te hunga he tirohanga tata, he tirohanga tawhiti, he astigmatism, he huinga hapa tirohanga rānei. I roto i te nuinga o ngā wā, ka whakamahia ngā karāhe tirohanga kotahi e te hunga e hiahia ana ki te nui o te kaha rite ki te kite i tawhiti me te titiro tata. Heoi, kei reira ngā karāhe tirohanga kotahi kua tohua mō tētahi kaupapa motuhake. Hei tauira, ko tētahi takirua karāhe pānui e whakamahia ana mō te pānui anake kei roto he karāhe tirohanga kotahi.
He mea tino pai te karāhe tirohanga kotahi mō te nuinga o ngā tamariki me ngā pakeke rangatahi nā te mea kāore e hiahiatia kia whakatikatikahia ō rātou tirohanga i runga i tō rātou tawhiti. Kei roto i tō whakahaunga mō ngā karāhe tirohanga kotahi he wāhanga porowhita hei tau tuatahi i runga i tō whakahaunga, ā, tera pea kei roto hoki he wāhanga rango hei whakatika i te astigmatism.
2. He aha ngā karāhe arotahi rua?
E rua ngā wāhi motuhake o ngā karāhe arotahi-rua mō te whakatikatika tirohanga. Ka wehea ngā wāhi e tētahi rārangi motuhake e tū whakapae ana puta noa i te karāhe arotahi. Ko te wāhanga o runga o te karāhe arotahi ka whakamahia mō te tirohanga tawhiti, ko te wāhanga o raro ka whakamahia mō te tirohanga tata. Ko te wāhanga o te karāhe arotahi e whakatapua ana mō te tirohanga tata ka taea te hanga i roto i ētahi huarahi rerekē: te wāhanga D, te wāhanga porowhita (kitea/kore e kitea), te wāhanga piko me te rārangi-E.
Ko ngā karāhe arotahi-rua te tikanga e whakamahia ana mēnā he tangata onge te tangata kāore e taea te urutau ki ngā karāhe arotahi-ā-mua, i roto rānei i ngā tamariki nohinohi e whakakōpiko ana ō rātou kanohi ina pānui ana. Ko te take e iti haere ana te whakamahi i ēnei karāhe, he raruraru noa kei te puta mai i ngā karāhe arotahi-rua e kiia nei ko te "peke whakaahua", arā, ko ngā whakaahua ka pekepeke i te nekenga o ō kanohi i waenga i ngā wāhanga e rua o te karāhe arotahi.
3. He aha ngā Arotahi Whakamua?
He hou ake, he matatau ake hoki te hoahoa o ngā karāhe arotahi whakamua i ngā karāhe arotahi-rua. Ka whakaratohia e ēnei karāhe he nekehanga kaha whakamua mai i te tihi o te karāhe ki raro, e tuku ana i ngā whakawhiti maeneene mō ngā hiahia tirohanga rerekē. Ka kiia hoki ngā karāhe mōhiti tirohanga whakamua he karāhe arotahi-rua kore-raina nā te mea kāore he rārangi e kitea ana i waenga i ngā wāhanga, e pai ake ai te ātaahua.
Hei tāpiritanga, ka hangaia hoki e ngā mōhiti tirohanga whakamua he whakawhiti maeneene i waenga i te tawhiti, te waenga, me te tata o tō whakahaunga. He pai te wāhanga waenga o te arotahi mō ngā mahi tawhiti waenga pēnei i te mahi rorohiko. He kōwhiringa kei ngā mōhiti tirohanga whakamua he hoahoa ara roa, he poto rānei. Ko te ara te wāhanga o te arotahi e hoatu ana ki a koe te kaha ki te kite i ngā tawhiti waenga.
I roto i te poto, he rerekē ngā otinga whakatika tirohanga a ngā karāhe tirohanga kotahi (SV), ngā karāhe tirohanga-rua, me ngā karāhe tirohanga-whakamua. Ka whakatikahia e ngā karāhe tirohanga-rua te tawhiti kotahi (tata, tawhiti rānei), ko ngā karāhe tirohanga-rua me ngā karāhe tirohanga-whakamua e aro ana ki te tirohanga tata me te tirohanga tawhiti i roto i te karāhe tirohanga-rua kotahi. He rārangi kitea kei ngā karāhe tirohanga-rua e wehe ana i ngā wāhanga tata me te tawhiti, ko ngā karāhe tirohanga-whakamua ia e tuku ana i te whakawhiti maeneene, āta haere i waenga i ngā tawhiti me te kore rārangi kitea. Mena kei te hiahia koe ki ētahi atu kōrero, tēnā whakapā mai ki a mātou.