What prompted me to start this thread was from the Photo Contest thread. I will quote myself and George here just to show what I am talking about
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In this thread we will discuss mainly "gear", or rather, cameras/lenses/photography related topics and basics. In this manner, we can have an open dialog on anything from, "what camera to buy?", to "what lens can achieve this look?".
So, let me start off with the quote from George above. Not to pick on you George but I know a lot of people that have a higher end camera and do not grasp the basic function of these cameras. Every single camera in the market today deals with these 3 basic things, without them, a camera does not work, and those 3 things are:
-Shutters Speed
-Aperture
-ISO
These are all relavent to an exposure, or a picture.
So, in basic terms, and I really do mean basic terms here:
-the Shutter speed decides how long (time-wise) the aperture stays open.
-the Aperture is the physical opening of a lens diaphram
-the iso simply measures the sensitivity of an image sensor
These 3 all work in unison to make a proper exposure.
Now, to apply this to a real world situation we must make up scenarios. The easiest shooting scenario is bright daylight. You can basically get away with using whatever settings you want.
In a night time setting, you are more limited in the type of settings you CAN use in that particular scene.
ISO is more important in darker situations but can be relied upon in daylight as well.
With this information in mind, consider that all lenses have apertures. Again, all this means is that the lens OPENS and CLOSES to its designated values. Typically, when someone refers to a lens as "wide open", it means that the lens is being used at its most open designation, so the physical 'hole' is large. If, someone refers to a lens as "stopped down all the way", it means that the lens is being used at its most closed designation. Why does this matter? It matters because the aperture controls something called Depth Of Field (DOF). When a lens is "wide open" the DOF is much smaller than when the lens is "stopped down".
These next shots are an example of DOF controlled by the aperture:
DeLeon Tequila Silver Top by
rickztahone, on Flickr
In this shot, the bottle cap was my main subject. I wanted to isolate it and make the DOF as small as possible. In this case I used aperture f/3.2. My lens could have opened up even further, in my case f/1.4, but when you are dealing with a subject in close quarters, the distance to the subject also comes in to play. This is an issue with many aquarium photographers, because most of the time they want to be pressed up against the glass to take photos. In reality, you are narrowing down your DOF which makes it more difficult to keep things in focus.
Think of DOF as a slice of pie. The wider the aperture, example f/1.2 (very wide) f/1.4, f/2, the THINNER your slice of pie is. The narrower the aperture, example f/5.6, f/8, f/11, the THICKER the slice of pie is.
DeLeon Tequila by
rickztahone, on Flickr
Moving on to this next shot. In this shot, I wanted to get more of the bottle in focus, not just the cap. In that case, I "stopped down", or simply narrowed the opening of my aperture (f/5). This allows a greater DOF. In this case, it allowed me to get the bottle in focus, as well as the cap, but the background still remains slightly out of focus. Had I stopped down even further, say f/11 for example, the background would have been more defined and sharp, or following our metaphor above, you would have gotten a larger slice of pie.
I may be getting to technical here, so I will let these points simmer and make themselves to your long term memory, lol. I will be back to explain shutter speed and ISO and how they rely on one another.
P.S. this is an open dialog thread and I will answer any type of photography questions. So, if it isn't related directly to what I said above because you know the basics, then please go ahead and ask a more advanced questions and I will try to answer to the best of my ability.