2 Mienzaniso yemibvunzo nezvezvishandiso zvemaoptical zvekamera
1. Kamera ye analog ine lenzi imwe chete ine urefu hwemasendimita gumi. Pakutanga, kamera yakagadzirirwa kutora mufananidzo wechinhu chiri kure. Kana mumwe munhu achida kushandisa kamera kutora mufananidzo wechinhu chiri kure nemamita mashanu, verenga:
(a) Kureba kuri pakati pefirimu nelenzi kana kamera yakagadzirirwa kutora mufananidzo wechinhu chiri pakusingaperi,
(b) Kureba kuri pakati pefirimu nelenzi kana kamera yakagadzirirwa kutora mufananidzo wechinhu chiri kure nemamita zana,
(c) Chinja nzvimbo yelenzi kubva pakuisa muchimiro cheinfinity kuenda pakuisa muchimiro chemita zana. Lenzi iri kure nefirimu here kana kuti iri pedyo nefirimu?
Kukurukurirana
Zvinozivikanwa kuti:
Kureba kwelenzi (f) = 10 cm = 100 mm
Mhinduro:
(a) Daro riri pakati pefirimu nelenzi kana kamera yagadzirirwa kutora mufananidzo wechinhu chiri pakusingaperi.
Kureba pakati pe lenzi nefirimu = kureba kwemufananidzo (s')
Chinhu chiri kure zvisingaperi zvinoreva kuti daro rechinhu (zvinhu) harina mugumo.
Kana kamera yagadzirirwa kutora mufananidzo wechinhu, daro riri pakati pe lenzi nefirimu rinogadziriswa kuitira kuti chiedza chinobva pachinhu chacho chitariswe ne lenzi kuti igadzire mufananidzo chaiwo pafirimu.
Panyaya yemalenzi e convex, zvakatsanangurwa kuti kana daro rechinhu (s) = kusingaperi ipapo jarak mumvuri (s') = kureba kwegirazi (f).
Kureba pakati pe lenzi nefirimu = kureba kwemufananidzo (s') = kureba kwe focal (f) ye lenzi = 100 millimeters.
(b) Kureba kuri pakati pefirimu nelenzi kana kamera yagadzirirwa kutora mufananidzo wechinhu chiri kure nemamita mashanu.
Nhambwe yechinhu (s) = 5 m = 5000 mm
Kureba kwelenzi (f) = 100 mm
Daro riri pakati pefirimu nelenzi = daro remufananidzo, rakaverengerwa uchishandisa fomura yelenzi ine convex nekuti lenzi yekamera ilenzi ine convex:
1/s' = 1/f – 1/s = 1/100 – 1/5000 = 50/5000 – 1/5000 = 49/5000
s' = 5000/49 = 102 mamirimita
(c) Kuchinja kwenzvimbo yelenzi kubva pakugadzika kweinfinity kuenda pakugadzika kwemamita zana
Kana yaiswa kuti itore mufananidzo wechinhu chiri kure nekusingaperi, daro riri pakati pe lenzi nefirimu i 100 mm. Kana yaiswa kuti itore mufananidzo wechinhu chiri kure nemamita mashanu, daro riri pakati pe lenzi nefirimu i 102 mm. Saka, shanduko iri pakati pe lenzi nefirimu i 102 mm - 100 mm = 2 mm.
Lenzi iri kure nefirimu here kana kuti iri pedyo naro? Ehe, lenzi iri kure nefirimu nekuti pakusingaperi, daro riri pakati pelenzi nefirimu = kureba kwelenzi. Kana lenzi iri pedyo nefirimu, daro riri pakati pelenzi nefirimu harisi pasi pe100 mm.
2. Magirazi maviri akapinza, rimwe nerimwe rine urefu hwe40 mm ne20 mm. Magirazi ese ari maviri anoshandiswa mukamera yeanalog kutora mifananidzo yechinhu chiri kure nemamita gumi. Sarudza:
(a) Kureba pakati pefirimu nelenzi kune urefu hwe40 mm apo kamera yakagadzirirwa kutora mufananidzo wechinhu chacho. Verengawo kukura kwemutsara.
(b) Kureba kuri pakati pefirimu nelenzi ine urefu hwe20 mm kana kamera yagadzirirwa kutora mufananidzo wechinhu chacho. Verengawo kukura kwemutsara.
Kukurukurirana
Zvinozivikanwa kuti:
Hurefu hwechitarisiko chegirazi re convex i1 (f)1) = 40mm
Hurefu hwechitarisiko chegirazi re convex i2 (f)2) = 20mm
Nhambwe yechinhu (s) = 10 m = 10.000 mm
Mhinduro:
(a) Kureba pakati pefirimu nelenzi kune urefu hwe40 mm kana kamera yagadzirirwa kutora mufananidzo wechinhu
Daro riri pakati pefirimu nelenzi = daro remufananidzo (s'), rinoverengwa uchishandisa fomura yelenzi ine convex nekuti lenzi yekamera ilenzi ine convex:
1/s' = 1/f – 1/s = 1/40 – 1/10.000 = 250/10.000 – 1/10.000 = 249/10.000
s' = 10.000/249 = 40,2 mm
Kukura kwemutsetse (m):
m = s'/s = 40,2/10.000 = 0,004 kanomwe
(b) Kureba kuri pakati pefirimu nelenzi ne 20 mm kana kamera yagadzirirwa kutora mufananidzo wechinhu
Daro riri pakati pefirimu nelenzi = daro remufananidzo (s'), rinoverengwa uchishandisa fomura yelenzi ine convex nekuti lenzi yekamera ilenzi ine convex:
1/s' = 1/f – 1/s = 1/20 – 1/10.000 = 500/10.000 – 1/10.000 = 499/10.000
s' = 10.000/499 = 20,0 mm
Kukura kwemutsetse (m):
m = 20,0/10.000 = 0,002 kanomwe
Enzanisa kukura kwemutsara uri mukuverenga uku nekwakapfuura. Zvichibva pakukura kwemutsara uku kuviri, zvinogona kugumiswa kuti kukura kwemutsara kunowedzera nehukuru hwe lenzi. Saka, pakusarudza lenzi yekamera, unofanirawo kufunga nezvehurefu hwayo hwemusoro. Kune zvinhu zviri kure, lenzi ine hurefu hwakareba hwemusoro inofanira kushandiswa kuwedzera mufananidzo unogadzirwa ne lenzi uye kurekodhwa pafirimu.
Kana tikatora mifananidzo yechinhu chiri kure tichishandisa kamera ine zoom lens, tinokudza mufananidzo unoumbwa nekuchinja malenzi uye kushandisa lenzi ine focal length yakareba. Tinogona kushandura malenzi nekuti zoom lens inoumbwa nemalenzi akawanda ane focal length dzakasiyana.
Pakutora mifananidzo yezvinhu zviri kure uchishandisa kamera ine lenzi imwe chete, zvakanaka kushandisa lenzi ine urefu hwakareba hwe focal. Lenzi iyi ine chimiro chakatsetseka.
