Controls & Settings
Controls that you will need to know - I won't bore you with controls you don't need to know or already do know.
Settings Dial (Found on top of your camera)
Ignore everything on this dial apart from M and B (If your camera has it).
M - Manual mode, does what it says, this is complete manual override and allows you to control shutter speed, aperture and ISO
B - BULB mode, if your cameras has this as a separate setting, other wise it will be on M past 30". You need a shutter release to use this mode, when you press the shutter release down the shutter opens when you release the shutter release the shutter closes. It's a vital tool for long exposures.
Settings Screen (Found on top of your camera)
WB - This button can control the white balance, which can be seen in the top left hand corner box. This can be a great tool for correcting orange tones in the sky, or I will explain later how this can be a handy tool to trick the camera in to changing the colour of the sky.
AWB stands for automatic white balance and is often the prefered option as it can be changed it RAW editor.
AF.DRIVE - We don't really need this button as it controls the frame rate and the different types of focusing. This can be seen in the two bottom right hand corner boxes.
ISO - This button controls the ISO, we can see the ISO at the bottom, and need to set ours to 100/500 depending on how well your camera handles noise, the higher the ISO the noiser your image will be.
The light - This may sound like a silly button but at night it's a bit of a life saver, I wouldn't suggest using it while in an exposure as you can slightly move your camera, I have ways around this which I will talk about later. It is good for checking and adjusting your settings.
Aperture - The aperture can be adjusted with the large dial on the back of the my camera and I mainly shoot at F/5.6 as this is a happy medium for a good exposure time and a sharp image.
Shutter speed - The shutter speed is also at the top of the screen so we need to bring that down to BULB which can be altered by turning the scroll button above the ISO control, or turn your settings dials to B if your camera has it.
The Battery level is displayed in the bottom left hand corner, which you will need to keep an eye on. Depending on your camera you can go in to your menu and it will tell you what percentage of battery your camera has left, otherwise you will just have to go on how many bars are left. I wouldn't let it get too low, make sure you charge your battery every time before you go out if it's below half or you have a big night of shooting planned.
Just to the right of the battery level you will see the light meter, you can ignore this totally at night as it will just tell you your image is under exposed. In BULB mode the light meter does not function at all.
Just above the light meter is a small box which tells you what file format your shooting in. I tend to only shoot in RAW because it has the most potential. If I shot RAW and JPG it takes up more precious space on my compact flash card. Some people only shoot JPG, some people like to shoot both. The only valid reason I can see you wouldn't shoot RAW is because your photoshop does not have the correct RAW patch which can be downloaded easily for free or you like the pure unedited jpg files.
Noise Reduction - Another useful control to have that can be found in the menu is the noise reduction tool. Depending on the camera sometimes is is vital to have it on, the higher end cameras can handle noise a lot better than the lower end ones, if you are not using noise reduction you will soon tell if you need it when you start shooting on the amount of noise that are in your images. I would not suggest using post production noise reduction as it smooths the image and loses a lot of vital detail.
Just right of this box is the spot metering, again you can ignore this because you don't use it at night. That's all the controls we need to know for our settings.
What The Controls Do
If you don't know these settings and what they do, here they are and a brief explanation of how they relate and work with each other.
There are 3 main aspects that will effect the exposure of your picture and they are Shutter speed, Aperture and ISO.
Shutter Speed - The shutter speed is the amount of time that light is coming in to the camera. For example at night a shot at 1/100 of a second will let in no light because of how dark it is, but a shot at 30" will let in a lot of light and help us to get the exposure we are after.
Aperture - The aperture is the amount of light coming in to the camera. For example an aperture of F/3.5 will let in a lot of light in to the camera but an aperture of F/22 will let in very little light.
ISO - The ISO is the sensitivity of the cameras sensor inside the camera (what the image is recorded on to). On most cameras ISO 100 is the lowest setting and ISO 1600 is the highest (1600 being the most sensative to light). Both produce very different results. ISO 100 will produce very little noise but ISO 1600 will produce very high amounts of noise especially at night.
Here are a few examples with theoretical situations of how these 3 settings have to work together to produce a good exposure. Just because an exposure is correct does not mean it is aesthetically pleasing. So we need to find a exposure combination that produces a correct exposure but with minimal noise. Remember at night we have to let a lot of light in to the camera to get our exposure. We also need to find a nice aperture that does not produce problems, aperture does not only let in more or less light it controls depth of field. If you don't know what depth of field is there are two types of depth of field and they are shallow depth of field and deep depth of field. Deep depth of field is where the whole image is in focus and can be achieved by using a smaller aperture like F/22. A shallow depth of field is where only part of the image is in focus and the rest is out of focus, a shallow depth of field can be achieved with a wider aperture like F/1.8. We don't really use shallow depth of field at night because it is not really successful in long exposures. So at night this can make the image look soft or out of focus because the distance in focus is smaller than if we were to use a smaller aperture but the smaller the aperture we use the longer the image will take to expose
Lets say we set an aperture of F/3.5 at ISO 100 for 30" - the image will be exposed some what correctly but the image may appear soft because of the shallow depth of field.
Lets say we set an aperture of F/22 at ISO 1600 for 30" - The image again will be some what correctly exposed but will now be very noisy because we have made the ISO higher.
If we were to shoot ISO 100 at F/22 we would have to expose the image for over an hour for our correct exposure, so we need to find a happy medium where the image is sharp and does not take too long to expose.
So my main rule is to keep the camera at ISO 100/500 at all times depending what your camera can handle, just to eliminate as much noise as possible. You can be temped to make the ISO higher to shorten your exposure and it may not look too bad on the back of your camera but wait until you get it on to a computer screen and you will see the noise as bad as it is. So now we are shooting at ISO 100/500 at all times that only leaves us two elements to sort out, Aperture and Shutter speed.
The shutter speed will obviously be on BULB so we need to find a nice aperture than can handle the exposure times we are going to be doing. I like to think of it this way, I set off my shot and go do my lighting for a few minutes by the time I come back and turn off my camera it should be about done, maybe a minute waiting or so. (you will get a better feel for it after some trial and error)
You do not want an aperture so high that you have to do your lighting for longer wasting your batteries in your flashguns and torches, but also you will have to wait around longer waiting for the sky to expose, resulting in an unsatisfying underexposed image. So I think F/5.6 or F/6 is a good aperture to shoot at, its wide enough to have a shorter exposure but not wide enough to make the image soft.
I think F/8 is a little too high but depending on the situation but it may be called for. In a highly light polluted city you may have to shoot at F/8 but in very dark environments with no street lights F/5.6 is a good place to start. Your situation will be different every time, look around you and make an informed decision about your aperture. Shooting in full moon light will expose faster than if there was full cloud coverage.