What Eric is describing is called "Aperture Priority mode" (or "AP" for short). It'll be one of the settings on the camera's manual/auto menu or dial. It's a half-manual setting, where you set aperture manually, and the camera handles exposure time automatically. Your camera won't stop the exposure automatically the way Eric describes unless the camera is set on this mode.
There's an "Exposure Priority" mode also, but that's for when you're capturing stuff with lots of movement, like live sporting matches, say.
Camera basics:There are basically only three variables to all cameras: ISO, Aperture, and shutter speed. All three control the amount of light captured ("exposure"), and share the same unit of exposure measurement ("stops") so that you can use any one to giveth back whatever another taketh away. This aspect can also be adjusted in Photoshop (within limits), so there's a tendency to think you don't need to worry about these: just use the auto settings, and if the exposure is a bit off, you can fix it later in photoshop.
However: each of these three settings has it's own unique trade off which cannot be fixed in photoshop (or to be exact: cannot be reduced in photoshop, only added to). This is their primary function: what actually makes them important and useful. Controlling exposure is only their secondary function. Thus, "just use auto and fix it in photoshop" can be a half-truth, depending on your application.
Lets get an ugly terminology snarl out of the way up front. "Exposure" means how much light is being captured by your camera in general. All three settings control exposure as their secondary function. "Exposure" is often confusingly used as shorhand for shutter speed, even though "exposure" really means "how much light is collected for a single pic, regardless of how that's controlled".
So for the purposes of this post, whenever I say "exposure", I always mean the broad definition. And whenever I mean "shutter speed", I will always say "shutter speed, or "time", never "exposure". Cool? Cool.
Also, regarding "stops": each of these 3 settings has it's own measurement system intended to deal with that setting's primary function, however each of these measurement systems is designed to use stop-equivalent units.
First up, ISO:ISO is a trade off between image clarity and light sensitivity. The higher the number, the less light you need to take the same pics, but the more grainy/muddy those pics will be. The lower the number, the clearer the pics will be, but the harder it will be to take those pics under less ideal lighting. ISO is measured in simple powers of 2, starting at 25 (though most modern cameras bottom out somewhere between 50 and 200), which are equivalent to stops.
When taking studio pics of your minis, with tripod, fixed lighting, etc., you'll want to manually set ISO as low as it can go. When taking pics of your game at the club or your mate's house, where lighting will be less certain, and the camera will be hand-held, you will probably have to turn the ISO up or to auto. IMO it's better to keep ISO manual, as auto settings will be more liberal with the ISO than they need to be, resulting in in pics that are grainier than they needed to be. IMO you always want to use the lowest ISO you can get away with.
If you want graininess for some aesthetic reason, it's better (more controllable) to add that in Photoshop. However, excessive graininess can't be fixed in Photoshop. You can smooth it's appearance in any number of ways, but you can't magically regain detail that was never captured to begin with.
Next up, Aperture:Aperture is the size of the shutter "hole" through which light passes to reach the camera chip. In cell phone cameras, webcams, and other ultra-compact cameras, this is fixed (there is no "aperture" or "aperture priority" settings in a cell phone camera's manual mode), as there isn't room for a variable mechanical shutter. In "regular" cameras, this is that mechanical iris thingy behind the lens.
Aperture's primary function is controlling
Depth of Field. This is the the amount of space in front of and behind the "sweet spot" of your focus which will also be in focus. The higher the number, the bigger your depth of field, but the less light is let in to hit the chip, so the shutter speed or ISO may need to be changed to compensate. The lower the number, the shallower your depth of field, but the more breathing room you have for your ISO or shutter speed. Aperture measurements are expressed in "f-stops", which is an incredibly woolly mathematical thing the only important part of which you really need to know is that it's also equivalent to stops in powers of 2.
When taking studio pics of your minis, you want your depth of field to be deep enough to cover the entire mini, but anything more is unneeded and so by going over you're just inflating your shutter speed for no reason. Moreover, A depth of field that cuts off between the subject and the background is a great way to ensure your background is well separated and abstract-ified.
When taking pics of a game at a club or your mate's house, you'll want a big depth of field to show the complex situation on the tabletop while also capturing your mate's gooney facial expressions and humorous eating habits for future mockery. This may force you to raise your ISO and/or lower your shutter speed to capture enough light. Auto settings typically prioritize depth of field (and thus higher aperture values), so you should be okay with auto.
Finally, shutter speed:Shutter speed is the time the shutter stays open, letting in light to accumulate into an image. Shutter speed's primary function is controlling
motion blur. The longer your camera takes to expose a single image, the more potential for motion blur there is. This is relevant both to photographing moving targets, but also to the camera itself moving. Shutter speed is expressed in fractions of a second, with the major intervals being powers of 2 corresponding to stops.
In a studio setting, you can set shutter speed as low as you need to if you have a tripod. The mathematical alignment between stops and shutter speed increments begins to break down at intervals larger than around 2 minutes, but you have to go really, REALLY long before it starts to become a problem (I did some night photography back in my student days involving shutter speeds up to 45 minutes long, and they all turned out fine).
When taking pics of your games at the club, you probably want to keep shutter speeds under 1/8. 1/60 is sort of considered the base line in academia, but in practice it all depends on how steady your arm is (or how slow your mates are). Unless the lighting is particularly bad, you can probably stick with auto here. BTW lenses with auto-stabilization are an amazing advantage, and you should get one if possible.
All of the above is not to slag off using auto settings. Auto gets most people by for most tasks, so it's fine. This is more to help understand and diagnose when your photos don't turn out well, so you know when and how to adjust things if you need to.
Hey, what about this "white balance" thing I've heard about?You camera isn't sapient, and as such can't tell the difference between an orange couch under white light, and a white couch under orange light. All it knows is that it sees orange. When you have many colors in frame, plus light sources with color biases, it can't tell what colors are accurate without being given a baseline for what white should look like under this specific lighting, either manually, or by using a preset, or via the auto setting, which works through some kind of color histogram averaging algorithm.
For still photos, this isn't such a big deal anymore, outside of extreme circumstances. Auto white balance tech has improved a lot in the lest decade, and can be relied upon well enough to where it usually only needs minor fixing in PS at worst.
For studio photos,
the CRI (Color Rendering Index) of your lights is what's really important. White balance is only the tip of the iceberg if the right colors aren't even present to be recorded to begin with. And while bad white balance can be easily fixed in PH, bad CRI cannot.
Video is where manually setting white balance in-camera matters more. If you've ever seen a video on youtube (usually shot on cell phone or webcam) where the color tint is constantly flickering between slightly yellow and slightly blue, this is because the auto white balance is constantly recalculating as stuff moves around in frame. If you plan on doing videos, please learn to set your white balance. Whether manual or preset, it doesn't matter, as long as it's locked in rather than left on auto.
Hopefully that helps, and isn't hard to read/understand. It was a lot of typing though, so I'll take a break before talking lenses.