Calculate the datum mark of exposure
Photography faces filmed scenery varied, in a picture scenery also has bright have dark, the difference is very big. Photography exposure wants emersion of accurate, comprehensive ground the object of these different light and shade, according to where should calculate exposure after all? Here involves the datum mark that will make exposure with the scenery of what brightness. Undertake filming below experiment. The object that be photographed is black (brown) , white, grey (green) 3 bottle still life, by ash (green) lubricious bottle measures light, because its surface layer glances,lead be equivalent to of 18% in grey, not only oneself can be correct reductive, and the shadow attune of other scenery, colour can receive satisfactory expression, by black (brown) lubricious bottle measures light, because object itself An is black, certainly will increases exposure. Film as a result deep brown bottle appears to be moved for neuter ash shadow, and grey bottle appears almost for white bottle, and original white bottle made plaster stone general, lacked detail administrative levels. Measure light by white bottle, because object itself is bright, certainly will reduces exposure. Film as a result white bottle appears to be moved for neuter ash shadow, and grey bottle appears for dark black, and original deep brown bottle appears for dead black, lacked detail administrative levels completely also.
From film the experiment looks actually, what serve as exposure according to the scenery be photographinged of the brightness intermediate only is fiducial (namely 18% glance the gray) of rate, sensitive data ability the scenery all sorts of all sorts of brightness, color according to the facts reductive, from black can convey respectively to white various administrative levels come out. If be with intermediate ash fiducial, press however dark (black) color and bright (white) color will calculate exposure, can cause exposure error, not be excessive, it is insufficient.
Can you still discover: from 3 afore-mentioned example? ? of box of Xiao of ぷ of Yu of lax of Xiu of of Ao of barrier of camel of Che of Jue holding sb in respectful awe holding sb in respectful awe no matter they measure which place exposure, after that scenery that is measured films sure present mix of shadow of the gray in be. So, the person that photograph must remember scenery of the gray in should choosing well to measure light, ability makes sure picture exposure is correct, ensure gray scenery is true emersion gray, subsequently black and white and polar also have to arrive corresponding and reductive. Why must press glance lead the gray of 18% to calculate exposure? This is the characteristic place decision of sensitive data. The scientist is designing sensitive data (include digital electron chip and film) with actinometer when, it is make light exposure in order to measure gray scenery for the standard, produce neuter density in order to make sure its are corresponding on sensitive carrier.
Control the medium of exposure
How does sensitive carrier allow when photography (digital electron chip and film) gain suitable light exposure, main control method is the aperture on camera and shutter. About the ABC of aperture and shutter, had told about in preamble. What need makes clear further now is, in exposure control what relation are they after all?
Common ground is told, correct exposure lets sensitive data accept appropriate light energy namely, it depends on proper aperture and shutter time were used when taking a picture. Can you hit a figurative: ? Sour pulls a surname reed however of full? aperture sizable at the size; of the window shutter leaves with respect to what resemble a window shut, the accident of shutter time is equivalent to the time length of window open. The light is strong, can open the window a bit smaller, or the time that opens a window is a bit shorter; light is weak, can open the window a bit more greatly, the time that opens a window is a bit longer, how many what enter the light energy inside house with this control. Can you still hit a figurative: ? To bring up puts in order agree to sigh shelter the degree of finish that show off conceives fellow? aperture to be equivalent to faucet, and the time that shutter is equivalent to turning on the water, thick pipe opens a few seconds to put one pool water possibly full; and thin tube may want ability a few minutes to put one pool water full. The task of the person that photograph chooses the combination of aperture and shutter according to the illumination of outside scenery namely.
In film, aperture and shutter are OK on the quantity that connect light mutual changeover, after deciding certain light exposure, the feeling luminous intensity that shadow carrier place accepts, leave big one class aperture and reducing one class shutter is equal. So, use the aperture that does not manage and shutter combination to be able to get identical light exposure. Film for example some scenery, the assorted; that correct exposure needs to use F4, 1/5008 so fall in same illumination condition, the combination of the combination that changes the combination that uses F5.6, 1/250s and F8, 1/125s and Fll, 1/60s can realize correct exposure, because combination of these a few groups of exposure brings into the light exposure of camera,be same.
According to afore-mentioned principles, can you reach such conclusion: ? Imperial mandate unplugs refine of Bi of mace grave Pi identifies? of You of sneer that a pavilion or house on a terrace to open big aperture, shorten the shutter time and stop down, exposure effect that lengthens time of exposure is same. And aperture is changeless extend shutter time, or shutter is changeless increase aperture, can increase light exposure. Open big aperture to extend shutter time again at the same time of course, light exposure is larger. The person that photograph understood this one flexible of aperture and shutter concerns, OK more agile ground is held accuse photography exposure.
Decide exposure advocate objective element
Light exposure is correct, video to the picture quality stand or fall is crucial, so photography of begin to learn must learn how to accomplish correct exposure seriously, be proficient in controls all sorts of elements of exposure. Baconian rise, here has the subjective factor of the person that photograph already, also have objective factor. It is the influence of subjective element above all, the artistic intent of the person that photography exposure wants a basis to film will decide, the introduction is analysed again in having the article after closing content to be in. The objective factor that affects exposure is as follows:
1. whether accurate determine to be photographed the illumination condition of the object.
2. whether hold video carrier correctly (sensitive film and digital medium) characteristic.
