Exposure?

Glassjaw · Jan 24, 2006

Say I was shooting at night in a dark enviroment with a few building lights. Would a longer exposure, say a few seconds or more, allow more light in and brighten the picture or is that depenent on the ISO?

Meysha · Jan 25, 2006

Exposure is dependant on three things.
ISO, shutter speed, and aperture. If you change any one of these then the photo will look different.... but in different ways.

If you change the ISO the level of noise or grain will change in your photos. A High ISO (ie 400 and above) means more grain. As you increase the ISO the sensitivity will also increase. So a photo at 1/10s at ISO 100 will be half as exposed as a photo at 1/10s at ISO 200.

Shutter speed controls how long the shutter is open. If you have the shutter open for a long time (relative to the object your shooting) then you will see blurry objects in your photo. Night time shots look nice with lots of blurry white lines from lights etc after about 5 seconds I've found. But again, it depends on the speed of your object. If it's just people walking that you want blurry you might need about 10seconds of exposure... if it's car headlights you want blurry you may only need 2 seconds. Try lots of different combinations.

Aperture changes the physical size of the hole that lets light in. So a small aperture will only let a little bit of light in - so to get the right exposure - you have to compensate by having a longer shutter speed. (I'm not confusing you am I?)
Aperture also cchanges how much of the photo is in focus. If you have a large aperture then only a really skinny part of the photo will be in focus. A small aperture gives you lots of the photo in focus.

Glassjaw · Jan 25, 2006

No I understand, but am not sure if my question was answered

. Disregarding other settings, if I set my exposure to 10 seconds in a dark setting with a few lights, everything is still, would that lighten up the photo more so than a 1/250s shot?

markc · Jan 25, 2006

Glassjaw said:
No I understand, but am not sure if my question was answered . Disregarding other settings, if I set my exposure to 10 seconds in a dark setting with a few lights, everything is still, would that lighten up the photo more so than a 1/250s shot?

You can't disregard the other settings. All together they make up exposure. That's like asking how the area of a rectangle changes by only mentioning one side.

If all the other settings stay exactly the same, then yes, the image would be a lot lighter.

Glassjaw · Jan 25, 2006

markc said:
You can't disregard the other settings. All together they make up exposure. That's like asking how the area of a rectangle changes by only mentioning one side.

If all the other settings stay exactly the same, then yes, the image would be a lot lighter.

Alright thanks, what I was looking for

.