shadie said:
Hi, i've juz got into photography a few months back and have read up a little regarding these features. Been shooting alittle with my PnS A95 which has some control of the aperture and shutter speed.. Now that i've gotten a nikon d50, i was wondering if anyone can put the relations in simple terms coz im getting quite confused abt them..
Aperture + shutter speed = Exposure level ?
does the aperture affects the depth of field ?
what does it exactly do ? :dunno:
I basically know how to control the shutter speed to get the kind of photos i want but im not exactly sure abt settings apertures. Appreciate if anyone can supply me the answers or links to my clarify my doubts. TIA :sweat:
let me try my go in explaining the way i understand it. i'm sure many had explained before but i got my way of understanding too, so just to share.
aperture opening size + shutter opening duration = amt of light onto sensor/film
the larger the opening, the more light enters.
the longer the opening remains open, the more light enters.
when the opening size and opening duration are sufficient big and long, the amt of light will be adequate and will give the desired exposure for that picture.
people usually use the analogy of a pail or a tap to describe it. as the aperture opening size and the shutter opening duration are reciprocal to each other, one of them goes up and the other goes down, eventually put together will even out to give the same amt of light.
however when on practice, the confusion starts as figures used are reciprocals of the above equation.
aperture opening size + shutter opening duration = amt of light onto sensor/film
1/aperture opening size + 1/shutter opening duration = 1/ISO
f/stop no. + shutter speed = ISO
when the aperture opening size
area is decreased by n times (
linearly 1, 2, 3, 4, 5....), the
diameter is also decreased by a
per-calculated protocol in which the denominator is the no. of times the diameter is decreased (if i didn't remember wrongly it goes f/1, f/1.4, f/2, f/2.8, f/4, f/5.6 ....). so while the aperture opening decreases (less light in), the f/stop number increases (less light in). note the reverse relationship.
when the shutter opening duration is decreased, i.e. faster, the time duration goes this way, 1sec, 1/2sec, 1/4sec, 1/8sec, 1/15sec, 1/30sec, 1/60sec..... on your camera, the time is recorded as 1, 2, 4, 8, 15, 30, 60 (most of the time as newbie we shoot at shutter speed less than 1 sec) .... in contrast to those more than 1 sec, i.e. 1sec, 2sec, 4sec, 8 sec are recorded as 1", 2", 4", 8"..... note that like the aperture opening, as the shutter duration decreases, the no. of times of division/splitting of a second increases, and the no. (without the ") will be becoming larger and larger. the no. of times of splitting of a second is the speed, the more it splits, the shorter the duration (less light in), the higher the speed (less light in) and the greater the number on the shutter speed on the camera. so this is again a reverse relationship.
ISO ratings give the sensitivity of the sensor/film to the amt of light. a low ISO rating has a low sensitivity and requires more light to give an output that looks bright enough. a high ISO rating has a high sensitivity and requires less light to give an output that looks bright enough. note again the reverse relationship, low ISO = more light required, high ISO = less light required.
now digest the reverse relationship for the above 3 things and make a note always to differentiate aperture size and f/stop no. that they are reverse, and differentiate shutter duration and shutter speed that they are reverse.
aperture opening size + shutter opening duration = amt of light onto sensor/film
1/aperture opening size + 1/shutter opening duration = 1/ISO
f/stop no. + shutter speed = ISO
now note the relationship between the 1st two elements on the left side of equation and the right side of equation.....let me reverse the equation.
ISO = f/stop no. + shutter speed
from the understanding of the equation,
when we increased the ISO, we can afford to increase f/stop no and the shutter speed. i.e. if we increased ISO sensitivity from 200 to 1600, (3 stop difference, 200 to 400, 400 to 800, 800 to 1600), we can increase the f/stop no. and the shutter speed by 3 times too, maybe 3 times for the f/stop no. or 3 times the shutter speed, or 2 times the f/stop no plus 1 times the shutter speed, vice versa.
from the understanding from the amt of light coming in, go back to the first equation and look at the last equation,
aperture opening size + shutter opening duration = amt of light onto sensor/film
more light in thru bigger hole + more light in with longer duration = more light in total
ISO = f/stop no. + shutter speed
less light required at higher ISO = less light in with higher f/stop no. + less light in with higher shutter speed
i hope the way i understand as a newbie, with various reading and attending lesson and the understanding exposure book, can help you to understand. the first block to the newbie is the up and down seems to refer to different things and are so confusing, so i hope you can get a better idea of the up and down of the setting....
for the experts, if there is any error in my explaination, pls correct me too....