Kinh nghiem chup anh: Huong dan chup anh chan dung (phan I)

Cho den thoi diem hien tai, nhung kien thuc co ban ve nhiep anh ma GenK gui toi ban doc co le da o muc “du xai”. Boi vay bat dau tu bai viet tuan nay, GenK se di sau vao huong dan ban doc cach chup tung the loai nhiep anh cu the, ma loai hinh duoc uu tien “mo man” chinh la anh chup chan dung – mot de tai GenK tin chac duoc rat nhieu ban doc quan tam.

 

1. Lua chon thiet bi

 

Lua chon ong kinh

 

Thiet bi dong mot vai tro quan trong trong anh chup chan dung. Tac gia ca rang 90% so anh chan dung ban bat gap tren Internet hang ngay duoc chup theo kieu “xoa phong mo mit”. Chup anh chan dung theo kieu xoa phong nhu vay duoc ua chuong, phan vi chung tao ra hieu ung lung linh cho phan hau canh phia sau, nhung quan trong hon, chung giup ta de dang co lap chu the ra khoi nhung vat the khong mong muon khac trong khung hinh, boi khong phai luc nao ta cung co dieu kien chup anh chan dung trong mot studio chuyen nghiep voi phong nen dung san.

 

De lam duoc dieu do, nhung chiec may anh compact co do zoom lon hay may anh DSLR voi ong kinh kit co ban nhu 18-55mm f1/3.5-5.6 chi co the cam cu duoc phan nao (xem lai loat bai viet Van dung do mo ong kinh) chu khong the la giai phap toi uu. Ban bat buoc se can mot ong kinh dap ung duoc mot hoac ca hai tieu chi sau:

 

-         Co do mo ong kinh lon.

 

Nhu da co lan nguoi viet nhac toi, do mo ong kinh chuan muc thuong duoc su dung trong anh chup chan dung la f/2.8. Nhu vay ban se can mot ong kinh co do mo toi da phai tu f/2.8 tro len. Can luu y rang cac con so 3.5, 2.8, 1.8,… do nam o phan mau so nen gia tri f/1.8 se lon hon f/2.8.

 

-         Co tieu cu khuyen cao tu tele tro len.

 

Khai niem “tieu cu tele” o day co doi chut phuc tap voi nhieu nguoi. Boi ta von biet rang than may anh ong kinh roi duoc chia lam hai loai, phu thuoc vao cam bien ma no su dung: fullframe hoac crop. Cac cum tu wide-angle (goc rong, duoi 35mm), normal (tam trung, tu 35-70mm), tele (tam xa, tren 70mm) khi noi ve tieu cu ong kinh deu duoc hieu la tren than may fullframe. Tuy nhien khi lap len than may crop, tat ca cac ong kinh deu bi nhan tieu cu len theo he so crop cua cam bien. Vi du voi ong kinh EF-S 18-55mm f/3.5-5.6 cua Canon, dai tieu cu 18-55mm ghi tren ong kinh nay duoc hieu la tren than may fullframe. Trong khi no lai la mot ong kinh chi su dung duoc voi than may crop, va do do dai tieu cu thuc te cua ong kinh nay phai la 28.8-88mm, do than may crop cua Canon co he so nhan tieu cu la 1.6.

 

Doi voi ca hai thuong hieu may anh duoc nhieu nguoi Viet Nam biet den la Canon va Nikon, ong kinh 50mm f/1.8 cua moi hang deu rat duoc ua chuong, so di cung vi chung dap ung duoc ca hai tieu chi tren, trong khi gia thanh lai rat re. Voi do mo lon (f/1.8) va tieu cu tele (50mm x he so crop = 80mm o Canon va 75mm o Nikon), ong kinh nay co kha nang chup chan dung kha tot, va do do GenK cung khuyen cao cac ban nen sam mot chiec tren con duong khoi dau nhiep anh.

 

Ong kinh EF-S 50mm f/1.8 mark II cua Canon co gia khoang $100.

 

Voi nhung nguoi co dieu kien kinh te cao hon hoac da su dung qua ong kinh nay va muon nang cap len mot lua chon khac tot hon, thi cap doi ong kinh 35mm f/1.8 (o Nikon) va 85mm f/1.8 co the se la cau tra loi hop ly danh cho cac ban.

 

“Vien ngoc duong pho” AF-S 35mm f/1.8 G cua Nikon.

 

Va “huyen thoai chan dung” Nikon AF 85mm f/1.8 D.

 

Ngoai hai yeu to tren, de co duoc tam hinh chan dung (luu y o day dang noi ve chan dung xoa phong) dep, ban doc con can biet den mot so khai niem khac nhu do sac net cua ong kinh, nguy co out net hay so luong la khau ben trong ong kinh. Trong do:

 

-         Do sac net cua ong kinh la kha nang chup hinh voi do net cao ngay tai do mo lon nhat. Thuc te co mot so loai ong kinh gia re hoac duoc san xuat voi cong nghe thoi “o-kia” chi dat duoc do sac net toi da khi khep khau do xuong f/3.5, tham chi f/5.6. Nhu vay nhung gia tri do mo lon hon neu co cua chung cung chi la vo tac dung. Mot so loai ong kinh khac lai chi net o vung trung tam ma bi “mem” (soft) tai vung ria anh. Dieu nay cung co the chap nhan duoc, tuy nhien se gay kho chiu neu bi “soft” nang.

 

-         Nguy co out net la khi ta chup voi do mo ong kinh lon, du da thuc hien thao tac auto-focus rat chuan xac va may cung da bao lay duoc net roi, nhung thuc te anh chup ra van bi mat net (nhoe) tai diem ma ta auto-focus.

 

-         So luong la khau: ta biet rang do mo ong kinh thay doi duoc la do su chuyen dong khep – mo cua cac la khau xep chong lien tiep nhau ben trong ong kinh. So luong la khau cang lon thi khi mo ra hay khep vao, do mo lo ong kinh se thay doi cang linh hoat hon, it tao ra cac canh va cac goc, do do bokeh khi len anh se cang tien gan toi hinh tron, mem mai va dep hon.

 

La khau va cach chung khep – mo de thay doi do mo ong kinh.

 

Co the de dang dem duoc so la khau ben trong ong kinh bang cach khep khau do lai gia tri nho

nhat. Trong hinh nay, ong kinh co 9 la khau.

 

Khi chon mua mot chiec ong kinh nao do, ban doc nen tham khao cac bai viet danh gia chat luong hoat dong va thong so ky thuat cua san pham de luu y cac yeu to nay. Ong kinh 50mm f/1.8 duoc nhac toi o tren co thong so ky thuat ly tuong la vay, nhung gia thanh re la boi vi chung chi co 6 la khau ben trong ong kinh, va xac suat bi out net khi chup o do mo f/1.8 la kha cao (tuy nhien, vi do mo chuan muc de chup anh chan dung la f/2.8 nen ta hoan toan co the khep nho khau do lai de khac phuc diem yeu nay).

 

Lua chon than may

 

Neu nhu ong kinh chiem den 60% chat luong cua mot tam hinh chan dung dep, thi than may chiem 25%, va 15% con lai danh cho cac thiet bi bo tro khi chup hinh trong dieu kien khong ly tuong (o day ta chi de cap toi van de thiet bi nen khong tinh den cac yeu to khac nhu kinh nghiem, ky thuat cua nguoi chup, kha nang tao dang cua chu the).

 

Doi voi than may, co mot so diem can luu y khi chon lua nhu sau:

 

-         Kha nang khu noise (nhieu, hat tren anh): du ISO thap nhat co the luon la lua chon hang dau trong nhiep anh chan dung, nhung doi khi trong nhung dieu kien chup phuc tap, ta khong co cach nao khac ngoai viec day ISO len cao. Mot chiec may anh co kha nang khu noise tot o dai ISO 400-800 se rat huu ich trong tinh huong nay. Khu noise tot duoc hieu la han che nhieu, hat tai nhung vung thieu sang ma khong lam mat di (qua nhieu) chi tiet cua hinh chup.

 

-         Kha nang chup lien tiep va toc do lay net nhanh: anh chan dung khong phai luc nao cung la chu the dung im (va cuoi moi mieng) doi chung ta chup. Vi du nhu chup anh bay chang han, kha nang chup lien tiep o toc do cao se giup nguoi chup de dang ghi tron ca mot qua trinh tu luc chu the nhun chan bat len cao cho toi khi tiep dat, roi chon lai mot kieu ung y nhat. Hoac voi anh chan dung doi thuong (hay con goi vui la chup trom), toc do lay net nhanh giup chung ta tranh danh mat khoanh khac quy gia va “ha guc nhanh, tieu diet gon” truoc khi doi tuong kip nhan ra va phan ung. Boi vay nen tuy khong qua quan trong, nhung kha nang chup lien tiep cua may cung la dieu can can nhac, tuy theo the loai anh chan dung ma ban muon theo duoi.

 

-         Can bang trang chinh xac: can bang trang (whitebalance) rat quan trong. Nguoi viet da tung thu nghiem chup anh chan dung tai vuon Bach Thao (Ha Noi) trong mot ngay troi co nang, khi thiet lap che do can bang trang tu dong tren Nikon D700, thi ket qua la 9/10 tam hinh mat chu the deu bi am sac tim. Nhu vay la ngay ca mot chiec may anh dat tien cung co the cho ket qua can bang trang sai neu de mac chung tu dinh doat so phan cua tam hinh. Khi do, nhung mau may anh co kha nang thiet lap can bang trang theo nhiet do K hoac custom preset de thiet lap can bang trang thu cong se huu ich hon rat nhieu.

 

Anh chup bang Nikon D700, set auto whitebalance trong Bach Thao bi am tim nang.

 

Thiet bi bo tro

 

Thiet bi bo tro thuong duoc su dung de khac phuc nhung kho khan ve mat dieu kien chup. Vi du voi anh chup chan dung nguoc sang, mot tam hat sang (thuong gap trong chup anh album cuoi) hay tam vai trang cang rong co the tao phan chieu va bo sung anh sang kha tot cho phia truoc chu the.

 

Su dung tam hat sang de bo sung them anh sang cho chu the.

 

Tuy nhien voi kieu chup “tu than phuc vu”, thi thiet bi bo tro huu ich nhat khong gi khac ngoai mot chiec den flash gan ngoai (external flash), bo dieu khien tu xa va gia do may anh (tripod). External flash co the gan ngay tren de den (hotshoe) nam tren dinh may, hoac khi khoang cach tu nguoi chup den chu the la rat xa (voi ong kinh tele) thi co the gan external flash len tripod, dat tripod o vi tri thich hop roi su dung bo dieu khien de kich hoat den tu xa trong luc chup. De anh sang phat ra tu den khong qua gat va chieu truc dien len mat chu the (de gay bet anh, loa sang), nen co mot chiec chup den lam nhiem vu tan sang (diffuser) nhu hinh duoi day:

 

External flash tham chi co the gan tren may anh du lich.

 

hotshoe hay con goi la de cam den.

 

Diffuser (cuc mau trang) giup tan sang, cho anh sang diu va toa deu hon.

 

Phan 1 cua loat bai viet Huong dan chup anh chan dung nay co the hoi buon te nhung lai rat quan trong. Don gian boi vi neu sai lam ngay tu khau chon lua thiet bi ban dau thi ban doc se khong the thuc hien duoc nhung tam hinh chup dung theo y muon va dat ket qua tot. Cung giong nhu viec biet truoc minh se phai ra tran ma lai chon mang theo mot chiec but viet thay vi khau sung vay. De lam ro hon cac van de lien quan toi thiet bi trong truong hop ban doc van ban khoan khong biet nen lua chon ong kinh nao, than may nao,… nguoi viet bai rat vui long duoc giai dap tat ca moi thac mac cua cac ban thong qua phan Binh luan ben duoi bai. Khi de lai cau hoi, cac ban nho cho biet:

 

-         So tien ma cac ban du dinh chi.

 

-         The loai anh thuong chup hoac du dinh se chup nhieu.

 

-         Dieu kien chup: ban ngay hay buoi toi, ngoai troi hay trong nha,…

 

-         Cac lua chon ma ban dang ban khoan (neu co).

 

Hen gap lai cac ban trong bai viet tuan sau, phan 2 hua hen nhieu dieu thu vi hon nua!