{"id":34,"date":"2014-07-20T15:36:45","date_gmt":"2014-07-20T14:36:45","guid":{"rendered":"http:\/\/www.enface.cz\/7x10\/?p=34"},"modified":"2014-07-20T15:51:59","modified_gmt":"2014-07-20T14:51:59","slug":"ostrost-v-krajine","status":"publish","type":"post","link":"https:\/\/www.enface.cz\/7x10\/34\/ostrost-v-krajine\/","title":{"rendered":"Ostrost v krajin\u011b"},"content":{"rendered":"

Je zn\u00e1mou skute\u010dnost\u00ed, \u017ee maxim\u00e1ln\u00ed optick\u00fd v\u00fdkon dosahuj\u00ed klasick\u00e9 objektivy p\u0159iclon\u011bn\u00e9 o cca 3 clonov\u00e1 \u010d\u00edsla. U krajin\u00e1\u0159sk\u00e9 fotografie obvykle vy\u017eadujeme zna\u010dnou hloubku ostrosti. Konstruovat vysoce sv\u011bteln\u00e9 krajin\u00e1\u0159sk\u00e9 \u0161irok\u00e1\u010de je tedy pouze marketingov\u00fd krok k osln\u011bn\u00ed z\u00e1kazn\u00edka. Chci-li dosp\u011bt k maxim\u00e1ln\u00ed hloubce ostrosti, mus\u00edm volit clonu 8\u201316. Se sv\u011bteln\u00fdmi objektivy v\u0161ak p\u0159i takov\u00e9m clon\u011bn\u00ed u\u017e obvykle nar\u016fst\u00e1 ohybov\u00e1 neostrost. Pro po\u017eadovanou nejvy\u0161\u0161\u00ed rozli\u0161ovac\u00ed schopnost by tedy objektiv nem\u011bl m\u00edt vy\u0161\u0161\u00ed sv\u011btelnost ne\u017e 4\u20135,6, proto\u017ee s citlivost\u00ed a t\u00edm souvisej\u00edc\u00ed d\u00e9lkou expozice dnes rozhodn\u011b probl\u00e9m nebude. U filmov\u00e9ho form\u00e1tu 4×5″ a svitkov\u00e9ho filmu to platilo beze zbytku. Jak\u00e9 je to dnes s digit\u00e1ln\u00ed technikou?<\/p>\n

<\/p>\n

Objevily se slibn\u011b vyhl\u00ed\u017eej\u00edc\u00ed „pancake“ objektivy univerz\u00e1ln\u00ed sv\u011btelnosti 2,8. Kupodivu pom\u011brn\u011b nevaln\u00fdch optick\u00fdch kvalit. Snad i proto, \u017ee i zde je implementov\u00e1n autofokus s vnit\u0159n\u00edm ost\u0159en\u00edm, i kdy\u017e by bylo opticky v\u00fdhodn\u011bj\u0161\u00ed ost\u0159it posunem cel\u00e9ho objektivu t\u0159eba manu\u00e1ln\u011b. Pro krajinu je optim\u00e1ln\u00ed ohnisko mezi 18\u201328 mm pro FF form\u00e1t, tedy12\u201318 mm pro \u010dipy APS-C. Tabulka hyperfok\u00e1ln\u00ed vzd\u00e1lenosti p\u0159itom stanov\u00ed, \u017ee p\u0159i clon\u011b 11 a zaost\u0159en\u00ed na 3 metry je hloubka ostrosti<\/a> p\u0159i b\u011b\u017en\u00fdch po\u017eadavc\u00edch od cca jednoho metru do nekone\u010dna, p\u0159i vy\u0161\u0161\u00edch n\u00e1roc\u00edch sta\u010d\u00ed zaost\u0159en\u00ed o metr posunout. Na\u010d tedy autofokus?<\/p>\n

Jako praktik se z\u00e1m\u011brn\u011b vyh\u00fdb\u00e1m slo\u017eit\u00fdm tabulk\u00e1m a obt\u00ed\u017en\u011b srovnateln\u00fdm test\u016fm. Ke zku\u0161enostem s\u00a0po\u017eadavky na vysokou kvalitu obrazu v\u0161ak pat\u0159\u00ed i stavebn\u00ed d\u00e9lka objektivu \u2013 o \u010dem\u017e se nikde nic nepublikuje. Nejvy\u0161\u0161\u00ed kvalitu u \u0161iroko\u00fahl\u00fdch krajin\u00e1\u0159sk\u00fdch objektiv\u016f dosahovaly dvojit\u00e9 anastigmaty typu Dagor, Angulon, Grandagon, u norm\u00e1ln\u00edch ohnisek pak Sironar, Symmar atp., jejich\u017e poloviny (se zhruba dvojn\u00e1sobn\u00fdm ohniskem) se daly pou\u017e\u00edt i samostatn\u011b. M\u011bly kr\u00e1tkou stavebn\u00ed d\u00e9lku \u2013 vzd\u00e1lenost clony od matnice prakticky odpov\u00eddala ohniskov\u00e9 vzd\u00e1lenosti. Ty star\u0161\u00ed m\u011bly sv\u011btelnost cca 8 a i ty nejmodern\u011bj\u0161\u00ed a nejdokonalej\u0161\u00ed neusilovaly o v\u00edc, ne\u017e 4,5. P\u0159itom snad platilo: \u010d\u00edm krat\u0161\u00ed stavebn\u00ed d\u00e9lka a men\u0161\u00ed sv\u011btelnost \u2013 t\u00edm kvalitn\u011bj\u0161\u00ed a ost\u0159ej\u0161\u00ed kresba i bez clon\u011bn\u00ed. Snad nejv\u00edc krajin\u00e1\u0159sk\u00fdch z\u00e1b\u011br\u016f jsem po\u0159\u00eddil Super Angulonem 8\/65 mm na form\u00e1t 6×9, srovnateln\u00fd s ohniskem 28 mm pro kinofilm. Pokud byl pot\u0159ebn\u00fd \u0161ir\u0161\u00ed \u00fahel z\u00e1b\u011bru, nem\u011bnil jsem objektiv, ale form\u00e1t, proto\u017ee Angulon vykreslil bez probl\u00e9m\u016f 9×12 cm.<\/p>\n

\"Tessar<\/a>

Tessar 1:6,3 s ohniskovou vzd\u00e1lenost\u00ed 105 mm je unik\u00e1tn\u00ed, v\u011bt\u0161ina dobov\u00e9 produkce m\u011bla sv\u011btelnost 4,5 a pozd\u011bji 3,5. Sv\u011btelnost je sice n\u00edzk\u00e1, av\u0161ak kresba brilantn\u00ed. Na sn\u00edmku je osazen v komo\u0159e KW 6×9 s miniiaturb\u00edni rozm\u011bry<\/p><\/div>\n

Dodnes opatruji miniaturn\u00ed unik\u00e1tn\u00ed Tessar 6,3\/10,5 cm ve star\u00e9m Z-D-M Compuru, kter\u00fd brilantn\u011b vykreslil form\u00e1t 9×12 cm, p\u0159i\u010dem\u017e jeho zn\u00e1m\u00fd bratr 4,5\/10 cm sta\u010dil jen na form\u00e1t 6×9. Obdobnou zku\u0161enost m\u00e1m i se sta\u0159i\u010dk\u00fdm Rolleiflexem modelu 6RF<\/a> 621 z roku 1935, osazen\u00fdm Tessarem „orl\u00ed oko“ 3,8\/75 mm, jeho\u017e ostrosti a rozli\u0161ovac\u00ed schopnosti u\u017e nedosahovaly modern\u011bj\u0161\u00ed verze 1:3,5 a posl\u00e9ze 1:2,8, a s n\u00edm\u017e se z form\u00e1tu 6×6 daly d\u011blat naprosto dokonal\u00e9 zv\u011bt\u0161eniny 50×60 cm. Jak m\u011b pou\u010dil geni\u00e1ln\u00ed mechanik, optik, konstrukt\u00e9r a oprav\u00e1\u0159 Dominik \u0160kola \u2013 cht\u011blo to ov\u0161em pracovat na ortochromatick\u00fdch (tedy dnes nejm\u00e9n\u011b citliv\u00fdch) materi\u00e1lech, proto\u017ee antireflexn\u00ed T \u010di MC vrstvy v t\u011bch letech je\u0161t\u011b neznali a obvykl\u00e1 aberace \u010derven\u00fdch paprsk\u016f sv\u011btla se na ortochromatick\u00fdch filmech holt nekonala.<\/p>\n

Pro\u010d se o tom zmi\u0148uji? Objektivy tohoto typu s kr\u00e1tkou stavebn\u00ed d\u00e9lkou, n\u00edzkou sv\u011btelnost\u00ed a vysokou rozli\u0161ovac\u00ed schopnost\u00ed se pro APS-C nebo FF form\u00e1t pro CSC p\u0159\u00edstroje nevyr\u00e1b\u011bj\u00ed. Snad proto, \u017ee na fotografie typu „v\u0161echno ostr\u00e9“ u\u017e t\u00e9m\u011b\u0159 sta\u010d\u00ed mobily. Rozd\u00edl v kvalit\u011b v\u0161ak v\u017edy bude ur\u010dovat velikost \u010dipu a dvojit\u00e9 anastigmaty s malou sv\u011btelnost\u00ed by i p\u0159i vysok\u00e9 kvalit\u011b mohly b\u00fdt cenov\u011b velmi p\u0159ijateln\u00e9. Ukazuje se, \u017ee FF form\u00e1t se i pro mirrorlessy s v\u00fdm\u011bnn\u00fdmi objektivy z\u00e1hy stane roz\u0161\u00ed\u0159en\u00fdm a p\u0159\u00e1l bych si, aby se konstrukt\u00e9\u0159i objektiv\u016f vr\u00e1tili k t\u011bmto mal\u00fdm a osv\u011bd\u010den\u00fdm „doppelanastigmatick\u00fdm“ konstrukc\u00edm uzp\u016fsoben\u00fdm pro sn\u00edmac\u00ed \u010dipy, umo\u017e\u0148uj\u00edc\u00edm bez degradace kresby i zna\u010dn\u00e9 clon\u011bn\u00ed.<\/p>\n

Z\u00e1v\u011br t\u011bchto \u00favah je nasnad\u011b: ne\u017e se tyto objektivy na trhu objev\u00ed, budou pro krajinu a street fotografii vyu\u017e\u00edv\u00e1ny zoomy nab\u00edzen\u00e9 v z\u00e1kladn\u00edm setu, nebo\u0165 kvalita sou\u010dasn\u00fdch „pancake“ pevn\u00fdch ohnisek nen\u00ed o nic vy\u0161\u0161\u00ed. Klasick\u00e1 kvalita sv\u011bteln\u00fdch manu\u00e1ln\u00edch objektiv\u016f zejm\u00e9na del\u0161\u00edch ohnisek vhodn\u00fdch pro portr\u00e9tn\u00ed fotografii, akt, m\u00f3du atp. v\u0161ak z\u016fstane pro pou\u010den\u00e9 autory trvale atraktivn\u00ed a v\u00fdrobci v \u010c\u00edn\u011b a Hong Kongu se zajist\u00e9 postaraj\u00ed o to, aby se daly aplikovat na jak\u00e9koli novinky progresivn\u00edch mirrorless\u016f 4\/3 form\u00e1tem po\u010d\u00ednaje a FF kon\u010de.<\/p>\n","protected":false},"excerpt":{"rendered":"

Je zn\u00e1mou skute\u010dnost\u00ed, \u017ee maxim\u00e1ln\u00ed optick\u00fd v\u00fdkon dosahuj\u00ed klasick\u00e9 objektivy p\u0159iclon\u011bn\u00e9 o cca 3 clonov\u00e1 \u010d\u00edsla. U krajin\u00e1\u0159sk\u00e9 fotografie obvykle vy\u017eadujeme zna\u010dnou hloubku ostrosti. Konstruovat vysoce sv\u011bteln\u00e9 krajin\u00e1\u0159sk\u00e9 \u0161irok\u00e1\u010de je tedy pouze marketingov\u00fd krok k osln\u011bn\u00ed z\u00e1kazn\u00edka. Chci-li dosp\u011bt k…<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-34","post","type-post","status-publish","format-standard","hentry","category-nezarazene"],"_links":{"self":[{"href":"https:\/\/www.enface.cz\/7x10\/wp-json\/wp\/v2\/posts\/34","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.enface.cz\/7x10\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.enface.cz\/7x10\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.enface.cz\/7x10\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.enface.cz\/7x10\/wp-json\/wp\/v2\/comments?post=34"}],"version-history":[{"count":0,"href":"https:\/\/www.enface.cz\/7x10\/wp-json\/wp\/v2\/posts\/34\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.enface.cz\/7x10\/wp-json\/wp\/v2\/media?parent=34"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.enface.cz\/7x10\/wp-json\/wp\/v2\/categories?post=34"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.enface.cz\/7x10\/wp-json\/wp\/v2\/tags?post=34"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}