Exposure and Aperture and Shutter Speeds….OH MY!

I’m beginning to see the light (*groan*). ;-)

Okay, okay so it's all still pretty Greek to me and I may never fully understand everything about the mechanics of taking a good picture, but after doing a quick run through of the "Quick Pro Camera Guides – Olympus E-510 DVD Tutorial" that I picked up on eBay a couple of weeks ago, I think I'm starting to understand a little bit about exposure, aperture and shutter speeds. (It's still gonna take a while for it all to gel together but at least I've stuck my baby toe into the water.)

In this segment, we'll briefly focus (double *groan*) on exposure, thanks to a wonderful analogy used in the DVD. I know, I know, analogies have never been YML's strong suit; well, okay they’ve never been *Shawn's* strong suit (remember the celery and peanut butter – or was it cheese whiz – debacle?). I rest my case.

Besides, this isn't my analogy it belongs to the guys at Quick Pro Guides, and it's an interesting one, at least interesting enough to keep my attention and have it, I think, even make some sense to me. And if it's not good enough, well…..it's their analogy, not mine.

:-)

Before I get to that though, let's look at the basic photographic definition of the words exposure, aperture and shutter speeds (taken from 2 different sites who shall remain nameless to protect the innocent or mentally evil).

Exposure:
(1) product of the intensity of light and the time the light is allowed to act on the emulsion (I x T = E).
(WTF!).

(2) The exposure is the amount of light received by the film or sensor and is determined by how wide you open the lens diaphragm (aperture) and by how long you keep the film or sensor exposed (shutter speed). The effect an exposure has depends on the sensitivity of the film or sensor.

Aperture:
(1) circular hole in the front of the camera lens which controls the amount of light allowed to pass on to the film.

(2) Aperture refers to the size of the opening in the lens that determines the amount of light falling onto the film or sensor. The size of the opening is controlled by an adjustable diaphragm of overlapping blades similar to the pupils of our eyes. Aperture affects exposure and depth of field.

Shutter speed:
(1) action of the shutter that controls the duration of an exposure. The faster the speed the shorter the exposure. Shutter speed settings are given in the fraction of a second. Each setting is half the duration of the preceding one in a constant scale, marked on the shutter speed dial or ring.

(2) The shutter speed determines how long the film or sensor is exposed to light. Normally this is achieved by a mechanical shutter between the lens and the film or sensor which opens and closes for a time period determined by the shutter speed. For instance, a shutter speed of 1/125s will expose the sensor for 1/125th of a second. Electronic shutters act in a similar way by switching on the light sensitive photodiodes of the sensor for as long as is required by the shutter speed. Some digital cameras feature both electronic and mechanical shutters.

(Eyes blinking wildly in confusion.)

If you're a true beginner to photography like I am this is what your brain got from that: blah blah exposure…..blah blah blah aperture…blah blah blah shutterspeed. Sigh. (And I don't doubt most of you are smarter than me, but work with me here.) ;-)

Now before you give in to temptation and start playing Snood – here comes the cool part and a simple analogy to explain the basic theory of exposure.

Think of it this way. The amount of light needed for proper exposure equals a full bucket of water and the tap used to fill the bucket with water is like the aperture or the opening on your lens. The duration of the camera's shutter is similar to the amount of time you'll need to leave the water turned on in order to fill the bucket; i.e., time water is on equals the time shutter is open. The "wider" the tap is open, the more water that will flow through the tap and into the bucket. This means the tap will only have to be open for a short amount of time.

However, if the tap only has a "narrow" opening, water can only trickle into the bucket thus making the amount of time you have to leave the tap open much longer in order to fill the bucket, i.e. get the proper exposure.

Neat eh? ;-)

Oh ok, you can go play Snood. But I bet you won’t forget about the bucket. ;-)

Next week, I'll go into a bit more detail about aperture, faster shutter speeds and shutter stops and how they all tie in together with exposure, as explained in the Quick Pro Guide DVD.

For now, just remember the amount of light needed for proper exposure = full bucket of water; the water tap used to fill the bucket = aperture (or the opening of your lens) and the time it takes for the water to fill bucket = the time the shutter needs to be open.

Sly

Information courtesy of Quick Pro Camera Guides – Olympus E-510 DVD Tutorial. If you want more information or to find out whether or not your camera has a DVD guide, please visit Quick Pro Guides.