I know there is a lot to think about when you are taking photographs and I keep adding things to your list, so here's a little Aperture guide for you.
Close-up images - one person portraits - f2.8
A small vignette where you want it all in focus - two people - f5.6
A group portrait - f8/f10 (depending on how many people!)
A landscape, building, a whole room where you want it all in focus - f16
This is a rough and ready list and meant to help you have a starting point and get an idea of how different apertures can work for different images. This certainly doesn't mean this is always these are the right apertures to use!
Controlling the aperture doesn't just help with deep of field but also with shooting in low light. Do you remember on Monday when I talked about the smaller the number, the larger the aperture and therefore, the more light that is let in?
The smaller the aperture number on a lens, the more light the lens will let in and the quicker the shutter will close.
If you are photographing indoors, for example, but not near your happy window then you will need a low aperture number to capture an image that is sharp.
If you want to take a portrait in the early evening when the sun is going down or at an event indoors then instead of using the flash you can use a low aperture number.
The 50mm 1.8 lens that I mentioned on Monday is a great lens for shooting in low light.
If you need to use a higher aperture number because your lens won't go down as far as 1.8, for example, or you want to get a deep depth of field then you will need to use a tripod because the larger the aperture number, the less light the lens lets in and the longer the camera will need to keep the shutter open for. The longer the shutter is open the more you will shake...or even just breathe...and your image will be blurry.
When you are shooting in Aperture Priority mode your camera will control the shutter speed for you, so you don't need to worry about that but you do need to be aware of it, so that if you are getting blurry images then you can either put your camera on a tripod or lower your aperture number.
There is a huge difference between depth of field blur (know as bokeh) and a blurry image due to camera shake!
In film photography ISO measured the sensitivity of the film to light. The lower the number (eg 100 ISO) the less sensitive the film and the finer the grain on the images produced on that film.
In digital photography the same ISO numbers are used and the sensitivity the numbers measure is the sensitivity of the image sensor. The higher the number the more sensitive your camera is to the light and the more grain will appear on your images.
On lots of your cameras you will have the option to use Auto-ISO. I was so excited when Auto-ISO came along because it meant that for most of the time I didn't need to think about the ISO and I could get on with concentrating on composition, light, focus points etc. However, because I already had a knowledge of choosing the right ISO, when my camera wasn't doing what I wanted it to and I wanted to override the Auto-ISO then I knew what I wanted/needed to do.
So, instead of just telling you to pop your camera on Auto-ISO and never worry about it, I want you to regularly spend time taking it off Auto and choosing the ISO you need for the circumstances you are shooting in.
You can also pay attention to the ISO that your camera is choosing for you when you are shooting in Auto-ISO mode.
Here is a list of good starting points for you.
ISO 100 outside, bright day
ISO 200 outside cloudy/dull day
ISO 800+ indoors
ISO 1600+ low light
Generally, you always want to use the lowest ISO you can to avoid grainy/noisy images. Unless of course you want to create that grainy look of film in your image.
However, higher ISOs allow you to shoot in low light without having to use a flash.
If you have taken your lens down to the lowest aperture it will go but your shutter speed is still too slow and your images are all blurry, then the next thing you can adjust is the ISO.
One thing to be careful of is if you have been taking images indoors at a high ISO and then go outside and forget to reduce the ISO down to a lower number you might find your images are overexposed or even sometimes just all white. Don't panic, just reduce the ISO back down. This used to always be a nightmare when I worked as a wedding photographer and I'd leave a dark church and then open the big doors to a bright Summer's day, usually walking backwards as the bride & groom walked down the aisle and out of the door. I'd be caught up in the emotions of the moment and focussing on capturing those and the composition. The last thing I wanted to worry about was turning down the ISO...which is one of the main reasons that I fell in love with Auto-ISO when I first had it on my camera!
Have a go at experimenting with the ISO, especially when you are indoors.
Exposure compensation enables you to make an image lighter or darker than the exposure your camera is giving you.
If you're image is feeling too light you turn it down, if it's feeling too dark you turn it up.
It's pretty much as simple as that!
To change your exposure compensation you need to find a button with a +/- on it and then turn your dial up and down to change it. Some of you will see it change in your view finder, others on your display...or both!
Do be careful though. It's super sensitive, so just increase or decrease by one little point...not a whole 1 or 2. These little points are called stops.
Inside I usually shoot at 0.5 or higher and on a sunny day outside I will shoot at -0.5 or lower.
From top left to bottom right: -2, -1, -1/3, 0, +1/3, +1
If I want to have a really light and bright image I will go up higher than I might usually go. And, in the same way if I want a dark and moody image I will go down lower than I would usually go.
When I am thinking about my exposure compensation I am considering two things:
1. Do I need to adjust for the current circumstances I'm shooting in? A dark room, a really sunny day etc.
2. Do I want to adjust it to create a particular look for this image?
Have a go at changing your exposure compensation. Take several images on different settings like I have done above and see what works for you in different situations. See what you like!
Wow...That was a lot of technical things all in one lesson. You might need to read this one a few times!
Aperture...how much of this image do I want in focus? Am I working in low light?
ISO....can I leave it on Auto?
Exposure Compensation...do I want to brighten or darken this image?
Keep practising and soon all this will come together!