Photography Basics Part 1
An article by January 23, 2008on
I’m not sure if there will be a part 2, but I thought it would be a good idea to keep it open just incase. After walking someone through the first steps of understanding photography from a SLR (Single Lens Reflex) perspective I thought I would write down the first lesson so that others could also benefit from it. It’s nothing you won’t read in a Photography text book, but then again, how many people do you know that just pickup a Photography text book for light reading?
In theory the perfect photo is a mix of the right light coming into the camera for a correct amount of time. We’ve all seen photos that were either too dark or too light, that’s the result of not having the correct combination. If you were to shoot an image that is too dark you can correct that by allowing more light into the camera. There are two (three, but we’ll get to the third one later on…) ways you can add more light to the image, make the hole that allows the light into the camera bigger or keep that hole uncovered for a longer time.
The size of the hole is called the Aperture and is marked by “F” and then a number. (F16, F5.6, etc.) When you have a number like F25 it indicates that the hole is very small whereas a number such as F3 would be large. By adjusting this setting you permit more or less light to enter the camera over a given amount of time, thus adding more light or shadow to the final image.
The aperture is only open for a certain amount of time, otherwise you would either have a completely black image or a completely white image. Your camera has a built in mechanism called a “shutter” that moves back and forth over the aperture. When you click the button to take your photo the shutter opens according to your instructions. If you only allow your shutter to be opened for a short amount of time you will need to be in bright light or have your aperture wide open to make the correct shot. On the other hand if your shutter is open for a few seconds you need to be in a dark area or have a closed shutter (and a tripod, because no matter who you are it will shake and become blurry.)
Combination of Speed and Light
Those two values work together to make your image. On my Nikon D80 I have a meter that tells me if the image is overexposed, underexposed or correct. If I were to look at the image and see that it is underexposed (or too dark) I could open the aperture or leave the shutter open longer. If it was overexposed (too light) I could go the other direction and close down the aperture or keep the shutter open for a shorter amount of time.
Personally I think that “the perfect exposure” meter (my name for it) is overrated and that it should be used only as a guideline. If you’re shooting a picture of something gray sitting on white snow your camera will quite possibly have a problem. You have to consider the focal point of your image. If you had that something gray on the snow you will probably need to keep the shutter open longer than suggested in order to capture the true color of the gray. It might overexpose but that can be a desirable look in some cases, you’ll have to watch the images on your screen to know (assuming you’re using a digital camera.)
The Third Part of the Equation: ISO
Once you’ve worked with aperture and shutter speed for some time and have started to get the feeling for it you should consider the ISO number of your film as a third piece of the exposure equation.
The ISO, back in the days of film, was intended to tell you how fast the film is at taking on light. If you shoot with a film that is rated at 1000 ISO it needs much less light than film rated at 100 ISO to make an image. This is really important for the perfect image because there are times that you can’t open or close the aperture any more and the shutter speed is already too fast or too slow for the proper exposure.
In the example mentioned before of the gray object sitting in the snow, if the final image is really bright and you had already closed the aperture almost entirely and sped up the shutter speed as much as possible then you probably need to change the ISO of your shot to a lower number. On the opposite side, if you’re at night and your aperture is wide open and your shots are blurring before they expose then you need to raise the ISO number.
What’s the Catch?
ISO numbers can be great if you need to make a quick adjustment to your settings. (if you’re using film don’t change the ISO to anything except what your film is rated to be shot at, you’ll be sorry otherwise. Ask me for the long answer of why I love digital SLR’s over film SLR’s and this will be part of my answer.) But the catch is this, if you’re shooting in a low light situation and you need to up the ISO number it’s going to start to look grainy.
You might not see it on your mid-range ISO numbers but it will start to show up quickly as your push the numbers higher. That’s why I typically shoot at 100 ISO unless I’m forced to do so otherwise. This might not be an issue for you if you don’t ever think you will blow your photos up past scrapbook size. I will also say that I have been really surprised at how well the Nikon D80 handles the grain on a photo shot at 1000 ISO, you just can’t see it like you used to on film.
There is a lot that goes in to making a photo work, sometimes it feels right to just let the camera handle it all for you but if you want the ability to really push the details yourself then you have to make the jump to operating your camera manually. There’s much more to say about the subject but that’s all a topic for a different time.
If you would like some supplemental reading or clarification reading here are some articles I would suggest, if you don’t look at anything else I highly recommend the first link listed below, it has a visual representation of the image as taken with different aperture and shutter speed values.