Question

lens in a camera and 1/p + 1/i = 1/f formula

Answer 1

1) for a particular camera, the focal length of its lens is fixed.

2) the image location of the light passing through a convex lens depends on the object location by the formula 1/p + 1/i = 1/f

Answer 2

if i may ask? What level of education is this?

Answer 3

this is 12th grade physics @ILovePuppiesLol

Answer 4

oh my goodness, let me just go to bed *slowly backs away*

Answer 5

doing my 9th grade biology ;~;

Answer 6

Here is the question :
The image location must change based on the distance the object is from the lens. But the location of the image sensor in a camera is fixed; then, how are we able to take pictures of an object at any arbitrary distance before the lens ?

Answer 7

Nice... this isn't hard @ILovePuppiesLol and I guess this is more of biology too

Camera works more or less same as the human eye. your eye is the camera, your retina is the image sensor... Human eye is able to focus object at any depth by changing the focal length of the lens. The muscles attached tot he lens contract and expand as you try to focus on objects based on the distance. But in a camera, the size of the lens is fixed; so the focal length is also fixed. I'm trying to understand how the "focus" in camera works...

Answer 8

i thought this was some sort to of matrix math that they teach in mathematician school

Answer 9

Is that really how our eyes work? I thought we focused by moving our eyes closer or further apart. But I guess if it's really our iris contracting that focuses then I guess by analogy a camera's aperture serves the same function:

https://i.ytimg.com/vi/F8T94sdiNjc/maxresdefault.jpg

Answer 10

aperture controls the amount of light passing through the lens right ?

Answer 11

small aperture requires less shutter speed so as to allow longer exposure times

Answer 12

how does that change the location of image ?

Answer 13

I don't know, I just thought like by analogy they are mechanically the same sorta shape and probably have the same sorta effect. I don't know how it works, just throwing that out there but I'm working on something else right now so I'll take a more serious approach later.

Answer 14

location of image sensor in camera is fixed, but,..the distance between the lens and the image is changing, because you zoon the lens, is it not? are you able to zoom the lens?

Answer 15

if so, the distance between the sensor and the lens is changing, though, the sensor itself is fixed

Answer 16

1/p + 1/i = 1/f

if `i`(image location) is fixed and `p`(object location) varies, then `f`(focal length) of the lens has to change right ?

Answer 17

no, f of lens does not change,

Answer 18

the first part of the sentence is the misleading one

Answer 19

@ganeshie8
i'm guessing you are thinking of those old cheap film cameras that dont come with any lens adjustment options.. ?

Answer 20

if i(image location) is fixed,...that is very misleading.

Answer 21

yeah, so i have to zoom in / out to be able to focus objects at different distances ?

Answer 22

One should ask the following question:
how is the distance i measured?
from where is it measured?

i is distance from the lens to the image location in camera

Answer 23

it is shown in my attachment...

Answer 24

if Camera is fixed in your hand, image location is fixed in your perspective. But, distance between image plane and lens is not fixed

Answer 25

http://assets.openstudy.com/updates/attachments/56ecdebee4b021ce9ad22dda-ganeshie8-1458364369953-zzz.jpg

Answer 26

yes,..if you zoom to get objects from different distances in focus, then, i will change

Answer 27

but, one's intuitive feeling of image being fixed inside your camera conflicts with the formula, and how the distances are measured in the formula

Answer 28

may be to keep things simpel... lets stick to a lens w/o zoom

Answer 29

so, it is always measured from the lens

Answer 30

then i can capture only objects at one particular distance is it ?

Answer 31

if its without zoom, then, it can correctly image only one distance

Answer 32

If you have digital processing enabled, that is another story altogether,...

Answer 33

thanks, that is all i wanted to know..

Answer 34

but, in the absence of that, yes, you can capture only objects at one particular distance

Answer 35

yw neshie

Answer 36

looks the aperture controls the blurness too
as we reduce the aperture, the rays from a point source entering the lens become more parallel, giving a sharper image

Answer 37

looks i need to take a quick photography course to understand these better