{"id":32,"date":"2014-07-12T08:51:36","date_gmt":"2014-07-12T07:51:36","guid":{"rendered":"http:\/\/www.enface.cz\/7x10\/?p=32"},"modified":"2014-08-09T11:25:26","modified_gmt":"2014-08-09T10:25:26","slug":"svetelnejsi-objektiv-je-lepsi","status":"publish","type":"post","link":"https:\/\/www.enface.cz\/7x10\/32\/svetelnejsi-objektiv-je-lepsi\/","title":{"rendered":"Sv\u011bteln\u011bj\u0161\u00ed objektiv je lep\u0161\u00ed?"},"content":{"rendered":"

Stalo se nepsan\u00fdm pravidlem, \u017ee FF form\u00e1t<\/a> 24×36 mm se stal dom\u00e9nou profesion\u00e1l\u016f a t\u011bch znal\u00fdch amat\u00e9r\u016f, kte\u0159\u00ed si ho mohou dovolit. U nich u\u017e se zku\u0161enosti, o nich\u017e se zmi\u0148uji daj\u00ed p\u0159edpokl\u00e1dat, tak\u017ee m\u00e9 \u0159\u00e1dky budou pov\u011bt\u0161inou ur\u010deny pro p\u0159\u00edznivce form\u00e1tu APS-C. Ten v digit\u00e1ln\u00ed \u00e9\u0159e zaujal postaven\u00ed d\u0159\u00edve obsazen\u00e9 kinofilmem. U t\u011bchto p\u0159\u00edstroj\u016f se v kvalitn\u011bj\u0161\u00edm z\u00e1kladn\u00edm setu dod\u00e1valy objektivy s ohniskovou vzd\u00e1lenost\u00ed 50 mm a sv\u011btelnost\u00ed <\/a>1,8 a 1,4. I dnes si tento rozd\u00edl jedn\u00e9 poloviny clonov\u00e9ho \u010d\u00edsla, vyj\u00e1d\u0159en\u00fd zkr\u00e1cen\u00edm pou\u017eit\u00e9ho \u010dasu t\u0159eba z 1\/60 na 1\/90 sec, udr\u017euje dvojn\u00e1sobnou cenu. Stejn\u011b jako se nyn\u00ed v\u00fdrobci p\u0159edh\u00e1n\u011bj\u00ed v \u010dasto zbyte\u010dn\u00e9m r\u016fstu megapixel\u016f, o p\u00e1r generaci d\u0159\u00edve to bylo se sv\u011btelnost\u00ed.<\/p>\n

<\/p>\n

Nejd\u0159\u00edve to bylo u 6×6 form\u00e1tu svitkov\u00e9ho filmu s tehdej\u0161\u00edmi triplety typu Tessar sout\u011b\u017een\u00ed mezi sv\u011btelnost\u00ed 3,5 a 2,8 (p\u0159i\u010dem\u017e ty 3,5 v\u011bt\u0161inou kreslily l\u00e9pe) \u2013 s n\u00e1stupem kinofilmu pak mezi 2,8 a 2, kde nep\u0159\u00edm\u00e1 \u00fam\u011bra mezi sv\u011btelnost\u00ed a kvalitou platila stejn\u011b. Triplety se toti\u017e s vy\u0161\u0161\u00ed sv\u011btelnost\u00ed ne\u017e 2,8 zkonstruovat nedaly a konkuren\u010dn\u00ed Biotary 1:2 s dvojn\u00e1sobnou v\u00e1hou, mno\u017estv\u00edm \u010do\u010dek a reflex\u016f m\u011bly podstatn\u011b m\u011bk\u010d\u00ed kresbu.<\/p>\n

\"Nocton<\/a>

Nocton 25 mm \/ f0,95 pro 4\/3 form\u00e1t (s kinofilmov\u00fdm ekvivalentem 50 mm) se sice krom\u011b nejvy\u0161\u0161\u00ed dosa\u017een\u00e9 sv\u011btelnosti py\u0161n\u00ed miniaturn\u00ed hloubkou ostrosti, ale s v\u00e1hou 410 g, velikost\u00ed portr\u00e9tn\u00edho skla se \u010dty\u0159n\u00e1sobnou ohniskovou vzd\u00e1lenost\u00ed\u00a0 a luxun\u00ed cenou t\u00e9m\u011b\u0159 20 000 K\u010d<\/p><\/div>\n

S p\u0159\u00edchodem japonsk\u00fdch zna\u010dek v 70. letech se toto soupe\u0159en\u00ed polo\u017eilo mezi sv\u011btelnosti 1,4 a 1,8. Tehdy \u2013 s limitovanou citlivost\u00ed negativn\u00edch materi\u00e1l\u016f cca 250 ISO<\/a> to snad m\u011blo v\u00fdznam: dal se „z ruky“ 1\/30 sec „na plnou d\u00edru“ po\u0159\u00eddit portr\u00e9t v no\u010dn\u00ed ulici. M\u011bl jsem prvn\u00ed Takumar 50\/1,4, s n\u00edm\u017e se takto dalo pracovat a z\u00edskat m\u011bkce ostr\u00e9 a rozz\u00e1\u0159en\u00e9 sn\u00edmky. Brilantn\u00ed ostrost ov\u0161em za\u010d\u00ednala na clon\u011b 5,6 a s clonou 11 nastupovala ohybov\u00e1 neostrost. Po p\u00e1r letech v\u00fdrobci objektivy zdokonalili, nicm\u00e9n\u011b st\u00e1le plat\u00ed, \u017ee \u010d\u00edm vy\u0161\u0161\u00ed sv\u011btelnost a del\u0161\u00ed ohnisko, t\u00edm je vykorigov\u00e1n\u00ed optick\u00fdch vad a z\u00edsk\u00e1n\u00ed vysok\u00e9ho rozli\u0161en\u00ed slo\u017eit\u011bj\u0161\u00ed. A raritn\u00ed objektivy sv\u011btelnosti 1,2 \u010di dokonce 0,95 jsou vhodn\u00e9 zejm\u00e9na k ozdob\u011b sb\u00edrek.<\/p>\n

Dnes, kdy se d\u00e1 b\u011b\u017en\u011b pracovat s citlivost\u00ed nad 1000 ISO u\u017e po\u017eadavek na vysokou sv\u011btelnost jako zbyte\u010dn\u00fd vy\u0161um\u011bl a rozd\u00edl mezi clonami 1,4 a 1,8 je tedy pouze v rozsahu hloubky ostrosti. Je zcela zbyte\u010dn\u00e9 m\u00edt objektiv sv\u011btelnosti 1,4 a clonit na 1,8 nebo 2 \u2013 pouze se t\u00edm degraduje bokeh (zejm\u00e9na neostr\u00e9 odlesky a sv\u011bteln\u00e9 zdroje), proto\u017ee tvar clony, kter\u00e1 m\u00e1 na to vliv, nen\u00ed u t\u011bchto objektiv\u016f ani zdaleka kruhov\u00fd. Zbyte\u010dn\u00e1 je ov\u0161em i honba za objektivy s mnoha clonov\u00fdmi lamelami s dokonale kruhov\u00fdm otvorem, nebo\u0165 pro dokonal\u00fd bokeh se stejn\u011b v\u016fbec neclon\u00ed.<\/p>\n

Velk\u00fd detail portr\u00e9tu na APS-C form\u00e1t s 50 mm nezaclon\u011bn\u00fdm objektivem m\u00e1 s clonou 1,8 hloubku ostrosti tak akor\u00e1t na o\u010di s toleranc\u00ed jen drobn\u00e9ho pooto\u010den\u00ed hlavy. S clonou 1,4, pokud tv\u00e1\u0159 nen\u00ed zcela front\u00e1ln\u011b en face, u\u017e druh\u00e9 oko „plave“. S prodlu\u017eov\u00e1n\u00edm ohniskov\u00e9 vzd\u00e1lenosti hloubka ostrosti kles\u00e1, tak\u017ee pro stejn\u00fd po\u017eadavek ostr\u00fdch obou o\u010d\u00ed pot\u0159ebujeme u 100 mm objektivu u\u017e clonu 2,8 a vy\u0161\u0161\u00ed sv\u011btelnost je tedy nejen zbyte\u010dn\u00e1, ale i nevhodn\u00e1.
\nMimo portr\u00e9t pak p\u0159i srovn\u00e1n\u00ed kresby dvou stejn\u011b kvalitn\u00edch objektiv\u016f zaclon\u011bn\u00fdch na stejn\u00e9 clonov\u00e9 \u010d\u00edslo obvykle ten sv\u011bteln\u011bj\u0161\u00ed rozhodn\u011b vy\u0161\u0161\u00ed rozli\u0161ovac\u00ed schopnost\u00ed nevynik\u00e1.<\/p>\n","protected":false},"excerpt":{"rendered":"

Stalo se nepsan\u00fdm pravidlem, \u017ee FF form\u00e1t 24×36 mm se stal dom\u00e9nou profesion\u00e1l\u016f a t\u011bch znal\u00fdch amat\u00e9r\u016f, kte\u0159\u00ed si ho mohou dovolit. U nich u\u017e se zku\u0161enosti, o nich\u017e se zmi\u0148uji daj\u00ed p\u0159edpokl\u00e1dat, tak\u017ee m\u00e9 \u0159\u00e1dky budou pov\u011bt\u0161inou ur\u010deny pro…<\/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-32","post","type-post","status-publish","format-standard","hentry","category-nezarazene"],"_links":{"self":[{"href":"https:\/\/www.enface.cz\/7x10\/wp-json\/wp\/v2\/posts\/32","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=32"}],"version-history":[{"count":0,"href":"https:\/\/www.enface.cz\/7x10\/wp-json\/wp\/v2\/posts\/32\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.enface.cz\/7x10\/wp-json\/wp\/v2\/media?parent=32"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.enface.cz\/7x10\/wp-json\/wp\/v2\/categories?post=32"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.enface.cz\/7x10\/wp-json\/wp\/v2\/tags?post=32"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}