It has occured to me that some of y'all are frustrated as all get out because you don't have the basic understanding of how the exposure parts work together...or even what they are.
I think going through UE is a great exercise and will help a lot of folks. That said, there are some really and truly basic things that maybe need explaining so that your dSLR is demystified a bit...so that you can take it off of auto mode, or program mode...or even off of aperture priority mode...and learn how to use it to it's potential in manual mode.
i'm going to start with aperture. Some call it ap, others call it Fstop. Essentially...the aperture is the opening in your camera that allows light to enter.
from dictionary.com:
ap·er·ture (pr-chr)
n.
1. An opening, such as a hole, gap, or slit.
2.
a. A usually adjustable opening in an optical instrument, such as a camera or telescope, that limits the amount of light passing through a lens or onto a mirror.
b. The diameter of such an opening, often expressed as an f-number.
in manual mode on your dSLR, you control the diameter of the opening of said aperture. a wider aperture is more OPEN and gives you a more SHALLOW depth of field. for example, this infant photo was taken with an Fstop of 1.8. that is the WIDEST open my 50mm lens can go...the aperture was WIDE OPEN allowing in as much light as it could. the effect is that the toes are in focus but a few inches away, the body and face are not = shallow depth of field. this works great for still life, some detailed forms of portraiture and the like. does not work for landscapes or groups of people.
conversely, if you "stop down" or close down your aperture to it's smallest end, you'll have a very deep depth of field. this works great for landscapes or something where the entire field needs to be in focus...but is distracting for portrait work where the main focus in on the subject since the background will be in focus. this example was last fall...the aperture or f stop was F22. that means that the hole was TINY in my lens...it was the smallest opening my lens could do, letting in as little light as possible.
you'll notice an inverse relationship to the numbers. a smaller number means a larger opening means a shallower depth of field. a larger number means a smaller opening and a deeper depth of field.
for groups of people or even just two people, middle of the road is best. an aperture of F6-11 works well. UE talks about F8 as being the "whatever" or "who cares" aperture. it's a good all-around zone for most things you'll do...this photograph was F7.1. you'll see that both children are in focus...the tree behind them is slightly less so but not blurred...and the background is fuzzy but not totally obscurred.
for one person, i tend to stay in the F 4-5 range because it leaves more focus on my subject but allows me to get them all in focus (as opposed to a wider ap/smaller number which would leave part of them out of focus...it has a deeper depth of field. make sense?) these photos next are the same one...just color/bw so you can see the difference in the same photo with conversion. the Fstop is 4 on this shot. (if it matters it's xt's daughter, rowan.)
for those of you using aperture priority mode, you are selecting your aperture based on the effect you want to make (depth of field) and allowing your camera to determine the shutter speed. i'll address that in my next PSA on exposure...but ultimately, aperture is the place most of us start when determining proper exposure. based on what we are shooting (group, landscape, still life) we determine the effect or depth of field we intend and we choose accordingly. THEN we address the shutter speed to get good exposure. again, i'll cover that in my next thread on exposure.
so...that wraps up my first trying-to-be-helpful show and tell about exposure. did this help anyone at all? i'm headed to bed but in the next couple days i'll pop in and post about shutter speed.
jules, feel free to post some examples to back up mine, k?
ok guys...let's talk EXPOSURE BASICS with your dSLR. #1) F stop or aperture
wife to toby 
Cherise
Ah well.
it does get harder. there is probably no way you're really going to get a successful indoor shot of all your kids in focus without some helping light/flash/proximity of a large window....
Linear Mode
