I've met a lot of people recently who own Digital SLR cameras but still shoot on auto. To me, this is a travesty, and is comparable to owning a luxury sports car but only taking it on 20mph drives. Sure, you look awesome driving in your fancy-shmancy-pants car, but you really haven't gotten use out of the awesome engine! So, in order to help my fellow photographers out (and perhaps bore the rest of you), I thought I'd post a few blogs about tips that have helped me become a better photographer (and let's face it, I still have a long ways to go!). The first one I thought I'd post about is Av mode (aperture priority; your camera sets the shutter speed and you set ISO and aperture), because I am a junky for awesome DOF (depth of field).
Before you start using Av, it'd be good to know what aperture is. Simply speaking, your aperture determines how much light reaches the image sensor. Most lenses will have an f-stop-- the lower the number, the wider the aperture. For example, my Canon 28-135 lens stops down to 3.5; this is as wide as it will go. The wider the aperture, the greater the DOF (this is also called bokeh). For portraits, I like to shoot wide open, but for landscape shots, I like to close the lens down a bit so that everything in my picture is in focus. If you'd like to read a more in depth description of aperture, Wikipedia has a good article HERE. Now to put it in motion...
Set your dial button on your camera to Av mode. I always try to shoot with the lowest ISO possible; this ensures that I have minimal noise on my images. So typically I will shoot at 100 or 200, and a rare occasion will I shoot at 400 ISO. To set your ISO, there should be a short stop button on the back of your Canon. Simply press that button and the different ISO options will pop up. You can also go to your menu button and scroll to ISO that way as well. Next, I have to decide at what aperture I want to shoot with; like I mentioned before, the lower the f-stop, the wider the aperture and the more shallow the DOF. To set the aperture (this is on a Canon) there is a scroll button located on the top right of your camera, next to the shutter release button. To make your f-stop lower, simply scroll to the left, and higher, scroll to the right. Now that your ISO and your aperture are set, you are read to shoot. The tricky part is making sure that you can shoot with all 3 (ISO, aperture and shutter speed) with what you have set. If there's not enough light, chances are, your camera won't be able to shoot the picture very well, if at all. If your camera is unable to shoot, your f-stop number in your viewfinder (the little green line of numbers that are on the bottom of your viewfinder show your shutter speed, f-stop and exposure meter) will flash. If it is flashing, you will need to increase your f-stop until your camera feels like it can expose the image correctly. If you get to the highest f-stop (my 28-135 goes up to 22) and is still flashing, you will need to increase your ISO setting. Be careful in increasing the ISO too high though, because like I said before, this will cause increased noise and decreased image quality. You might have to fiddle around with your settings until you are satisfied, but that is basically how you shoot in Av.
