How can you make a photo underexposed and overexposed?

Question

Im taking a photo class and our first project is about exposure.
We have to shoot the subject at normal exposure and then also 2 stops under-exposed and over-exposed.
I know that under-exposed means darker but how do I do that? Like what do I do with the shutter speed and f-stop?
And what about making it overexposed?
And how can I use the light meter to help guide me?

Im supposed to be taking these pictures outside btw.
and I have a Pentax ZX60 camera with a Pentax 28-90 lens.
Do i have to do anything with the lens for exposure?

And does anyone know about the Pentax ZX60? I think my teacher said that instead of making it 2 stops over/under exposed, I'm supposed to make it 4 half stops because my camera has more numbers. This is true right?

And does anyone know what AV means? Aperture? Do i have to do anything with the aperture to change the exposure? How do you change it?

Sorry about all the questions, Im just a little confused.

thanks for the answers guys, they were all helpful. i finished taking my pictures today and i think i did a pretty good job. But tomorrow we are developing the film so then ill be able to see how i did. thanks for the help though!

Answer 1

Hi,
Glad to see someone who is still using a non digital camera. You are right, underexposed means making the pic darker (in simple terms). However in technical terms it means that you subject the scene (that you want to shoot) to less light. And how can you do that? By increasing the shutterspeed OR reducing the aperture. I suggest you just reduce your aperture by 2 stops. So just check the reading given by your light meter, and set the aperture to two stops below.

Similarly overexposing means subjecting the scene to more light. And you can achieve this by either reducing your shutter speed or increasing the aperture.

Your lens does not have to do anything about it.

What your teacher says is probably right on the f stops.

AV means Aperture priority. It in turn means that if you set the camera to AV mode, only then you will be able to adjust the aperture of your camera.

As mentioned above, you have to change the aperture to change the exposure. Can you please let me know the numbers that show in the AV mode..they are like F/1.4, and so on...

Hope it was of some help to you.

Answer 2

what you're doing is called bracketing and it's an excellent habit to get into. basically what bracketing does is compensates for possible errors that your light meter may (and often does) give you.
compose your shot and take a meter reading. decide which is more important to you: shutter speed or depth of field. if you're doing an action shot where you want to freeze or capture motion blur then set your shutter speed (based on your meter reading) and use the f/stops to bracket.
if depth of field is more important, i.e., you want to blur the background or have lots of detail throughout, then set the aperture and use the shutter speed to bracket.
let's say the meter reading tells you to use f/11 @ 125. if aperture is your priority you'd shoot 3 frames of the same image. the first at your initial meter reading, then f/11 @ 500 (underexposed), and f/11 @ 30 (overexposed). notice the f/stop is constant throughout.
if shutter speed is your priority then you 3 frames would be shot thusly using the initial meter reading from above: initial meter reading, f/22 @ 125 (underexposed), and f/5.6 @ 125. notice again that shutter speed is constant throughout.
there is a 3rd way that you may be able to do depending on your camera. some older manual cameras will have a dial that has things on it like EV +1, +2, +3, 0, -1, -2, -3. this is called exposure value and by taking a meter reading and then taking 2 more frames; one at +2, and another at -2. this is an automatic way of bracketing and much faster. but check your camera to see if you have it and read the documentation on how to exactly set up your camera to do this.

Answer 3

Harvinder is right, good answer. The aperture and shutter work in combination to produce the exposure. You can over or under expose by adjusting both or either. Or you can set your film speed to a different number and achieve the same thing.

Let's say your meter says shoot at f/2.8 for 1/60 for "correct" exposure. You are using 100 speed film. You could manually set your ISO to 400 speed. Now you are underexposed by 2 stops. To over expose, shoot at f/2.8 @ 1/15. Or f/1.4 @ 1/30. Underexpose 2 stops f/2.8 @ 1/250. Or f/5.6 @ 1/60. It's all reciprocal. A wider aperture equals a faster shutter speed and a smaller aperture needs a slower shutter speed to obtain the same exposure. Wider apertures mean less DOF for portraits or such where you want the background out of focus. Narrow apertures mean more in focus from foreground to background, such as landscapes.

Imagine your picture's exposure is a bucket that you want to fill with water. If you use a big hosepipe (aperture) then you leave the faucet (shutter speed) on for a short time. If you have a tiny hose pipe, then you have to leave the faucet running longer. Both ways will fill your bucket.

Have fun with your photography class!

Answer 4

1) If you have an assigned textbook, read it. It should tell you what to do. - I'm not saying this to be mean. I just took a beginners course and my book helped me out

2) Like what the other people are telling you, Set the aperture and shutter speed where the meter tells you that the reading is "good"
From there, what we were instructed to do, was to move the shutter speed to under and overexpose.
The textbook should have a list of shutter speeds, if not you can find it online. Also, like your instructor said, since you have 1/2stops you'll need to compensate for that.
Does your meter have a "tall"notches and "short" notches?
If so, then the tall notches would represent 1stop from each other.

Answer 5

photo underexposed overexposed

Answer 6

Underexposed Photo