Well, it’s not really “holy” per se, but it is something you NEED TO KNOW if you plan on trying to shoot in manual. How you set each of these different controls on your camera will determine if you under- or over-expose your photos. I tend to lean towards under-exposing, as my camera’s LCD screen usually shows the photos to be better exposed than they really are. Very annoying.
So…I’ll give a few quick explanations here, plus a link to someone who knows SO MUCH MORE than me, plus here is a book that gets raves reviews from amateur photographers. I have it at home…I just haven’t read it yet. I’m just far too busy taking photos to learn how to take them. 🙂
Here is a pretty detailed discussion on exposure, which is basically how light or dark your photo turns out.
ISO – Here is a great explanation of the term. Basically, you want to keep this number at 400 or lower, but truly mine is set at 800/1600 so often in the winter. This adds grain to your images, but if you have the photo exposed properly with a high ISO then it doesn’t show so much.
Shutterspeed – Again see the detailed explanation here. This is another setting that sets your light sensitivity but at the expense of movement. Since I have toddlers (i.e. faster than the speed of light movement at all times), I will set my shutterspeed as high as I can at the expense of a higher ISO.
(In brief: High ISO = BAD, High Shutterspeed = GOOD)
Aperture – Last, but not least, is the aperture. Lenses generally have a minimum/maximum aperture value. My kit lens only goes down to around 4.0, but my new lens goes down to 1.8 (happy dance!). If you can’t get your aperature down to a lower number (which means that it is wide open and lets in lots of light), then it doesn’t really matter what your settings are for the shutterspeed or ISO. This is why I absolutely needed my 50mm 1.8 lens. I really did need to have the ability to set my aperture down to the lowest setting, as indoors is hard to take pictures without that option. Setting the aperture low also gives you a shallow depth of field (meaning: a blurry background), which is great if you have subjects really close together. If you want to take group shots you need to be far away to have a setting at 1.8 (or thereabouts), but a 4.0 is usually the setting you would want otherwise not everyone will be in focus.
(In brief: Low Aperture = more light, which is good if you are okay with a shallow depth of field)
Now, you just need to figure out how all these things work together, right? Remember that book that I linked to above?? Confused yet? I like to confuse people…it’s what I do.
First, I set my aperture to what I need. Sometimes I have to go all the way to the widest/lowest setting to get the needed light. Then I start fiddling with my shutterspeed, which I like to keep above 200 at the minimum (remember those moving kids??). Next is the ISO, which I set at the lowest I can get it.
How do I know I’m exposing correctly?
There are two places on my camera that shows the exposure (well, besides the LCD screen after I have taken the picture). In the viewfinder there is a horizonal line with 0 in the middle and hash marks on either side. When my controls are all wonderfully exposed correctly, then it is at 0…if not, then it’s back to fiddling. This however doesn’t guarantee that it is properly exposed. Based on where the camera is “looking” it could be on a pretty bright area, like a window in the background, and that would under-expose the rest of the picture, which could be your cute little child sitting in front of the window.
The second place is the histogram. Here is a good discussion on using the histogram. You basically want all the lines in the middle instead of on either end.
Using all the settings is just a learning process. I can’t tell you how many photos I deleted because I didn’t have the exposure set properly. Although you can fix an under-exposed photo in Photoshop, there are limits and it does add grain to the photo. It is really hard to fix an over-exposed photo since the detail is all blown out and there isn’t anything there to bring back. So…if you are going to screw up at all, under-expose, which is why I clearly choose to screw up that way. Just kidding.
I have been trying to expose correctly, but it is hard to get it perfect. Maybe I should read that book.
That’s why Photoshop is my friend. More on that in the next installment. I have a few books on that, too, and have actually read a little of them!