What is Exposure? A Tutorial


Yayawar in making...
Just stumbled upon this.. Nice thread Henry. Haven't seen any much simpler explanation of the relationship between f-stop (aperture) and shutter speed. Nicely explained. Thank you! :) Rated 5 stars!
Henry, you wrote it in such a simple language that anyone can understand. Appreciate it!

I would like to share this article with people who keep asking me why I am taking so much time and number of clicks to take various shots.

Its all about mastering exposure and the composition that can transform an average click to beautiful shot.

Rate 5 *****



Parveen Dua

Active Member
Beautiful tutorial Henry. I have just bought d3200 with 18- 105 lens. and will start experimenting with it. How do you decide how much Fstop or ISO to keep is there and thumbrule or you just learn by experience??


Beautiful tutorial Henry. I have just bought d3200 with 18- 105 lens. and will start experimenting with it. How do you decide how much Fstop or ISO to keep is there and thumbrule or you just learn by experience??
Thanks Praveen.
Well, the F/stop setting depends upon desired depth of field you want to achieve. For portraits narrow dof is desired. To get this this the aperture needs to be opened-smaller no. For landscapes large dof is desired and this is achieved by narrow aperture-larger no. However, while using narrow aperture in low light the shutter speed may get too low. Therefore, to avoid camera shake a tripod is necessary or the ISO has to be bumped up to get faster shutter speed.


never ever give up
Full Auto Mode

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Nearly all modern cameras provide a fully automatic mode that does everything
for you but compose the shot and decide when to press the shutter
button. Full Auto mode evaluates the lighting; selects the ISO, white balance, aperture, and speed settings; and even decides whether the scene needs a little extra light from the built-in flash. This is a good mode to use if you’re new to digital photography and you still don’t know much about your new camera but you want to take pictures right away—or when you need to hand the camera to someone else to take a picture of you.
Keep in mind that some camera features, such as the abilities to change the
ISO, adjust the exposure with exposure compensation, and shoot in RAW format, may not be available in Full Auto mode. To gain an extra level of control and customization while enjoying the ease of automatic operation, you may have to use another automatic mode that is commonly called Program.

Program Mode

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Program mode is similar to Full Auto mode in that the camera selects the
appropriate aperture and shutter speed to deliver the correct exposure for
the scene you’re photographing. You also have the ability to modify the settings
the camera has chosen by shifting the aperture–shutter speed combination
to select a mix that better serves your creative goals ('Partnership'in action).
On DSLRs you usually make this adjustment by dialing a control
wheel until you arrive at a desired aperture or shutter speed, something
you can do without taking your eye away from the viewfinder.
Program modes also offer access to more advanced features of the cameras, such as shooting in RAW format, exposure compensation, higher ISO settings, and choosing a custom white balance. Because it offers the convenience of being fully automatic with the flexibility of changing some of the settings, you may find that Program mode works well for many situations.

Aperture Priority Mode

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Aperture Priority can be thought of as a semiautomatic mode because it relies
on you to decide which aperture to choose while the camera supplies the appropriate shutter speed. Once you select a given aperture, the camera constantly adjusts the shutter speed in response to changing exposure conditions, but the aperture remains the same. This mode is an excellent choice for images where depth of field issues take precedence over shutter speed. A wider aperture
causes the background to be more out of focus, and a smaller aperture yields
a photo with more areas of the image in focus. Aperture Priority is excellent
for portraits where you want only the subject in focus (use a smaller ƒ number
for a larger aperture) and for scenic shots where you want good depth of field
throughout the scene (use a larger ƒ number for a smaller aperture).

Shutter Priority Mode

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Like Aperture Priority, Shutter Priority is a semiautomatic mode. You decide
what shutter speed you want to shoot with, and the camera chooses the correct
aperture. Shutter Priority is ideal for situations where exposure time
is more important than depth of field. If you need to freeze motion, such as
with sports or birds in flight, using this mode allows you to select an appropriately
fast shutter speed. If your aim is to use motion blur creatively, such
as the classic rendition of moving water in a stream, you can also use Shutter
Priority to choose a slow shutter speed. Depending on the speed of the
object you’re trying to blur, you may need to use a tripod so that stationary
elements in the image remain sharp.

Manual Mode

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With Manual mode you have to do all the work. Well, maybe not all the
work. The camera does provide a light meter to tell you if your settings will
give you a properly exposed image, but you have to turn the dials or push
the buttons and make sure that aperture and shutter speed are set correctly.
Although a Manual mode is essential for photographic control and those who want as many creative options as possible, it’s not as spontaneous as some of the other modes, and realistically you may only need to control either aperture or shutter speed to achieve the effect you want. For some situations, however, such as night photography and in the studio, having a Manual mode is critical.

Scene Modes

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Scene modes are preset configurations that are designed for you to use under
specific shooting conditions to achieve good results without having to think
about the optimal camera settings. They’re not exposure modes you would
use all the time. You’ll find these modes on many digital cameras, from compact
point-and-shoot models all the way up through entry level DSLRs. You'll not find this on a pro-DSLR.
The actual names and modes vary from camera to camera (other terms
include Best Shot and Creative Assist modes), and depending on their
features, some cameras may offer more sophisticated interpretations.

Happy shooting
3 cheers!!!


Hi [MENTION=16765]hensil[/MENTION],

I understand that camera uses metering to decide the exposure.
If I am clicking in full Manual mode, how does metering come into picture?
The reason for this question is, Last weekend I was just playing with my D3100(in Manual mode). I shot two images (inside room), one with a person and other without a person. In both the images I could see a slight difference in exposure for the wall. What am i missing?
Both the pictures were clicked in quick succession on a tripod so i dont really think frame or light changed.