How to do Long Exposure light painting star trails

What is Long exposure?

Long exposure in essence is the slowing down of your shutter speed to allow more light to enter the camera.

When you increase your ISO then you are allowing more light (digital chip more sensitive camera chip is to light) thus the higher the ISO the brighter your image will be, but the higher the ISO the more noise there will be in your image. For long exposures I recommend that you go to the lowest ISO your camera can go to: ISO 100.

The next setting to keep in mind is your f-stop. If you open your f-stop then it will allow more light into the sensor. So for long exposure photographs I recommend that you set your Aperture (f-stop) between: f/11-f/22 (small opening of your lens will allow less light to enter your camera).  Tip: if yo want to do long exposures during the day or at sunset then I would recommend that you set your Aperture to f/22, but for night time photography I would use a f/stop of f/11 – f/16. If you use a foreground object for example a tree then you can manage your depth of field with your aperture, thus with a higher numbered f-stop more of your photo will be in focus, and with a lower f-stop number your depth of field will be shallower.

The shutter speed setting will determine how long your camera’s mirror stays open to take a photograph, and will record everything in the set amount of time. Thus it is important to set your ISO and Aperture settings correct to enable your camera to capture not too much light or too little light. Primarily you will set the camera to Manual mode. In manual mode you can set your camera to BULB mode. This will enable you to connect your cable release to your camera to control the amount of time your shutter stays open, which can range from a minute to a couple of hours (depending on the life of your battery).

Composition

How to compose

Overview

Ensure that you include as much as possible sky into your photograph; this will ensure that the primary focus of the photograph is on the star trails. A good rule of thumb is between 30% and 50% of your photo frame must include the sky. Ensure that your foreground is clear, and not too distracting – but add to the value of your photograph. Lastly make double sure that your horizon is straight, off centre photographs does not look nice, and distract the viewer’s attention away from your subject.

Composition

I would recommend that you scout your location first during daylight. During the day you can properly plan your photograph, and see the “lay of the land” This will enable to choose the most optimal site with the most effect for your photograph.

Mount your camera as well on the tri-pod and take a test photograph or two to ensure that you got your desired composition correct. Ensure that you place your tri-pod as well on a solid surface – which will ensure that your photograph comes out very sharp. Another tip is to connect a 2 litre water bottle to the bottom of your tri-pod (there is usually a hook onto where you can connect the water bottle) this will assist your tri-pod to become more stable. Connect as well your cable release, as this will ensure that there is no camera movement when you activate your shutter. Camera movement will cause your photos to display blurry, no matter how well you focus on your landscape and stars.

Ensure that you include as much as possible sky into your photograph, this will ensure that the primary focus of the photograph is on the star trails. A good rule of thumb is between 33% fore-ground image and 66% sky. Ensure that your foreground can give some perspective of of your planned scene, for example to include a tree, car or a house. Make double sure that your horizon is straight, off centre photographs does not look nice, and distract the viewer’s attention away from your subject.

Composition is one of the most important parts of shooting a long exposure photograph, and thus plans your photograph, and this will make the difference between a good phto and a awesome photograph.

\How do you do: Light Painting

You can use a torch to highlight your foreground landscape when you start taking your photograph. I would suggest to carefully lighting the scene. You can do this by diffusing the light by standing far away from your subject, and flashing the light over the subject from different angles. Be careful of using too much or too little light. If you use too much light then your scene will be too white and harsh and when you use too little light your foreground scene will be too dark. Be careful of using too much light from the back of your camera as this will create a too harsh scene with too much light, but rather try and light your scene from the sides, and other angles. A good rule of thumb is 1 minute lightning for every 10 minutes of long exposure.

Setting Up

This section will provide you with the technique for photographing the Long Exposure Star Trails. The primary settings to remember is that you must use low ISO, slow shutter speed and varying apertures to compensate for the low light conditions.

The following steps show you how to get ready:

1.    Plan your trip – find a venue which is away from the city, plan around the phases of the moon (dark moon is the best). Winter is usually best for this kind of photography due to there not being a lot of clouds. Note: make sure that the venue where you take the photographs is safe,

2.    Wait for the sun to set,
3.    Take snacks and a lot of water with an extra jacket with you,
4.    Make sure you have a fully charged battery, with a spare battery, as capturing the stars takes a lot of power from your camera,
5.    Mount your camera onto your tripod,
6.    Connect your cable-release to the camera

Focusing

The next step is one of the most important parts: how to focus onto the Long Exposure Star Trails. It is important to take the time to focus your photographs to pinpoint clarity, and it is one of the few times where you cannot rely on your camera’s autofocus system. Your camera’s auto focus system will not be able to focus on the Long Exposure Star Trails as there is not enough contrast for it to focus on specific stars due to the stars being too small.

Follow the following steps to focus on the Long Exposure Star Trails:

1.    Set your lens to MF (there are two options AF (Auto Focus) and MF (Manual Focus)),
2.    If your lens has image stabilization, then switch it off (the reason for this is: in the evening your lenses will constantly try to stabilize due to the low light conditions, and may soften your sharpness of your image),
3.    If your lens has the infinity symbol on the focus ring (∞) then set move the focus to there. But if your lens do not have this setting then do not stress, just continue to the next step,
4.    Switch your camera’s live view on,
5.    Move your camera that it points to the Long Exposure Star Trails,
6.    Zoom your lens out to the minimum (widest field e.g. 18mm) ,
7.    Turn your focus ring until you can see the stars with pinpoint accuracy. You achieve pinpoint accuracy when the stars do not look like blobs. This can be a painstakingly slow process, but well worth it,
Once you’ve achieved the perfect focus, and then lock your focus on your lens (another flip button on your lens. This will ensure that you have perfect focus for the whole evening’s photos.

 

Camera Settings

Overview

Always remember that your camera will pick up more stars than what your eyes can see, and thus you must always take test shots until you are happy with the outcome of your photo. I recommend that you take quite a few test shots because the image ay look fine on the live-view, but on a computer screen it may look totally different.

The three primary settings you should use is the ISO, Aperture and shutter speed. ISO, Aperture and shutter speed combination will determine the amount of light that gets captured, and it is essential that you get the combination right.

Taking your first test shot:

1.    The first step would be to set your camera to the following settings: ISO = 100, Shutter Speed = BULB Seconds and Aperture f/11,
2.    Cover your eyepiece, because that is allowing extra light from the back of your camera into the camera sensor, and this may lead to “light-leaks”. You can cover this with a small light cloth, or a camera strap,
3.    Press your cable release, and take the photograph (take your first photo for approximately 1 minute to determine your sharpness, and to check your composition),
4.    Do NOT touch the camera in any way – as this will cause vibrations, and much up your photograph. If you touched your camera by accident in this step, then please redo from step 1, and
5.    When the photo is finished then look at it in playback

In Playback make sure that all the start rails and have pinpoint accuracy. If they are not very sharp then re-focus your lens until the ultimate sharpness can be obtained. If your photo is sharp then sit back and admire your first photograph.

You may have noticed that some of your stars look elongated when you zoom into the image. This is caused by the length of exposure of your photograph.

Settings

Now what are the right settings into taking the ultimate Long Exposure Star Trails photograph? Follow the following guidelines and you will be able to photograph brilliant Long Exposure Star Trails Photos.

White Balance

Go into your white balance menu setting (if you do not know where this is then refer to your camera’s manual) and change it to AWB (Auto White Balance) this will generate a standard photograph where your camera will highlight all colours equally.

Exposure

The two primary settings to control in astrophotography are shutter speed and aperture. These two settings manage how much light will be captured by your camera. The amount of light is important because most stars are faint, and you would like to capture as much as possible of this faint light in the dark.

Note: Just ensure that there is NO artificial light coming into the camera as this may and will ruin your shot.

Aperture

I would recommend setting your lens to the mid-range aperture e.g. f/11 so that you capture enough light to see, but not too much that your photograph is overexposed. Sometimes I vary the maximum aperture between f/11 to f/22 to create different effects on the photo, and depending on how much natural light there is in your surroundings.

Shutter Speed

Set your shutter speed to BULB mode. This will allow you to control the amount of time your shutter stays open. Connect your cable release to your camera, and use a stopwatch to determine how long the camera has been taking the photograph.

The question is: How long should you keep your shutter open when photographing a long exposure photograph. This depends on the length of the star trails you would require or want in your shot. I would suggest that you first take a test shot of approximately 1-5 minutes to ensure that your composition is good. Thereafter I would take a shot of about a hour and a half. The next evening I would then push that time to at least two and a half hours to ensure that you have nice movement of the stars in your star trails.


ISO
I would recommend using ISO level of 100, but the most important part is that you take a couple of test shorts with each ISO level to ensure that your photograph produces the best result with your type of DSLR camera.

What Settings do I use?
Finally, to summarise I would use the following settings to take great Long Exposure Star Trails Photos:

Set your White Balance (AWB), Aperture (f11), Shutter Speed (BULB) and ISO (100). Now you are ready to start taking your photograph. I would recommend leaving your shutter open for approximately a hour and a half to two and a half hours to maximize the amount of star trails. And lastly remember to have fun, because two and a half can seem veeery long 😉
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