Aperature - Shutter Speed

In a simple way, can someone please explain to me aperature and shutter speeds in relation to taking u/w photos, as well as top side. This is confusing me... I've done some reading, BUT...

Thx.

A.

...by the way I've got an Olympus C4000Z

I'll try to take the overly simplified approach to this. Some light conditions give you more light coming into the camera than other conditions (ie. dark room vs sunny day outside). The camera needs to adjust the exposure to allow a certain amount of light into the camera. This is done with aperture and shutter speed. Aperture is a circular opening in the lens that changes size. Shutter speed is a curtain at the back of the lens that completely opens and closes at different speeds. Let's look at this from a manual setting point of view. Let's say that you are outside on a sunny day. This will probably give you a shutter speed of 1/500 and an aperture of f8 at a film speed of 100. Since both the shutter speed and the aperture control the exposure, if you change one you must change the other. The higher the number of the shutter speed the less light is getting into the camera (because the curtain is opening and closing faster). The higher the number of the aperture the less light is getting into the camera (because the higher the number the smaller the hole). There are reasons why you might want to change to a different combination of shutter speed/aperture settings but we won't get into that now. As I said earlier if you change one you must change the other. Here is a list of combinations that would give you exactly the same exposure results even though they are different sets of numbers: (original setting 1/500-f8) 1/1000-f5.6, 1/2000-f4 or going the other way 1/250-f11, 1/125-f16. All these are equal in value just as 2+2 gives you the same answer as 3+1.

This is step one. I'm sure others will chime in but I am trying to keep this very simple. If you understand this and want to move on, let us know and we will make it more complicated

The late, great Jim Church's justly famous "cows through a gate" analogy may be the clearest and best explanation of how shutter speed and aperture work in photography. Certainly the best explanation for anyone who has encountered difficulty with the standard textbook coverage. See:

Jim Church's Cows

This is the link to the first page - there are side links where Jim goes on to expand the analogy to explain depth of field, film speed, lenses, light meters, pushing and pulling film, etc.

R.

That cows analogy is awesome! I must remember it.

Aaahhh....thanks, this helps a lot. I'm sure I'll be back when I'm ready to get more technical. Have a good one, and thanks again.

Andrea

The key thing to remember about aperture vs exposure time for underwater photography is that, since the strobe fires for a very brief time, the exposure time

does not affect the amount of light arriving from the strobe. You can easily test this for yourself with a macro shot - on a deep dive, set your camera for f22, and take a strobe-lit shot at 1/60, looking down. Then, take the same shot at 1/120. You'll end up with pretty much the same thing, even though you used a much shorter exposure the second time.This is because essentially all your light for the shot was coming from the strobe, which only actually fired for a few millliseconds.

The exposure time does, however, greatly effect the amount of ambient (sun) light. This becomes important when taking wide angle shots, where you wish to balance the amount of light coming from ambient sources, and the brightness of the sunlit water surface (or the sunburst itself). You can take advantage of this - if you have a setup in which the water surface is exposed the way you want it, but the strobe-lit portion is not

bright enough, you can open up the aperture one stop, and shorten the exposure by 1 stop. This will produce a picture in which the ambient-lit portion (the background and blue water) is the same brightness, but the strobe-lit portion is brighter.

Wishing I could shoot with strobe exposures at <1/500,

chrisg