How to do Time-lapse Star Trails

1.1        Overview

This article will cover how to do Time-Lapse Star trails. I usually do Time-Lapse star trails when there is too much light around you, which may spoil your photograph, or when there are some clouds around in the sky. Time-Lapse star trails method provides you with the opportunity to modify individual “frames” or remove unwanted “frames” in your photograph.

Time-Lapse Star trails in essence is taking hundreds of single photographs and then combining it at the end. This allows you to control your individual photographs light on a shorter basis, so that a singular light source from in front of your photograph does not spoil your photograph.

1.2        Composition

1.2.1          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.

 

1.2.2          How to Compose

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 Time-Lapse Star Trails photograph, and thus plans your photograph, and this will make the difference between a good photo and an awesome photograph.  

1.2.3          How do you do: Light Painting

I would recommend to perform light-painting on one of your photographs – so that you have one photograph in which the foreground is perfectly exposed. 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. 

1.2.4          Setting-up

This section will provide you with the technique for photographing the Time-Lapse star trails. The primary settings to remember is that you must use high ISO, slow shutter speed and varying apertures to compensate for the low light conditions.

The following steps show you how to get ready:
1.       Connect your camera to your Tri-Pod
2.       Connect your cable release to your camera
3.       Set your camera to M- Manual mode
4.       Set your camera to continuous shooting
5.       Set your shutter speed to 30seconds
Now you are ready to start with your Time-Lapse star trails photograph. 

1.2.5          Focusing

The next step is one of the most important parts: how to focus onto the Time-Lapse 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 Time-Lapse 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 Time-Lapse 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 Time-Lapse 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. 

1.3        Camera Settings

1.3.1          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 = 1600, Shutter Speed = 25 seconds and Aperture f/2.8,
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 (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.  

1.3.2          Settings

Now what are the right settings into taking the ultimate Time-Lapse star trails photograph? Follow the following guidelines and you will be able to photograph brilliant Time-Lapse star trails Photos. 

White Balance
Your test photograph will look very white with no colour in it. This is because your camera took the photo in neutral white as part of the auto white balance setting. To compensate for the lack of colour you must change the white balance to between 3200k and 4800k. The easiest way to do this is to 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 from AWB (Auto White Balance) to Tungsten (Tungsten is close to 3200k). This will generate a warmer photo with more colours in it. 

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. 

Aperture
I would recommend setting your lens to the maximum aperture it can go to e.g. f/2.8 so that the maximum amount of light can be captured by your camera. Sometimes I vary the maximum aperture between f/2.8 to f/7.1 to create different effects on the photo, and depending on how much natural light there is in your surroundings. For example if there is some light pollution from a city close to you then I would use an aperture of approximately f/7.1.  

Shutter Speed
The rule of 500 is used to determine the optimal shutter speed. The rule of 500 indicates: what is the optimal time to set your shutter speed before the stars lose their round shapes. This may sound confusing but it is actually simple. I’m going explain it for the crop sensor cameras and full frame cameras (If you require a more detailed explanation around the rule of 500 then please feel free to google it).

A crop frame camera crops the image by 1.6 thus the calculation is 
Shutter seconds = 500 / (Focal Length X 1.6)

Thus if your camera’s focal length is set to 18mm the calculation would be:

Shutter Seconds = 500 / (18 X 1.6) which gives you 17 seconds. This means you can leave your shutter open for 17 seconds before the stars in your photograph stars losing its sharpness and round shapes. 

A full frame camera does not crop an image, and thus the calculation would be:
Shutter Seconds = 500 / (18) which gives you 27 seconds. This means you can leave your shutter open for 27 seconds before the stars in your photograph stars losing its sharpness and round shapes. 

ISO
The last setting which you must set on your camera is the ISO. ISO will determine the sensitivity to detail in your image, the higher the ISO the more detail, and the lower the ISO fewer details will be shown in your photo. One of the drawbacks of using a higher ISO is that it will generate more noise in your photograph.

I would recommend using between 800 and 3200 ISO level, 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 Time-Lapse star trails Photos: White Balance (Tungsten), Aperture (f2.8), Shutter Speed (30seconds) and ISO (1600) 

1.4        Taking the Photographs

Now that you are ready, press your cable release and “lock it” Your camera will then start continuously shooting pictures of the night sky, I would time the length to approximately 2 hours, so that you have nice movement of the stars. The biggest thing to remember is NOT to touch your camera – as this will influence your picture, and create a “distorted” look. 

1.5        Putting it all Together

1.5.1          Overview

I use an application called StarStax to compile your hundreds of star-photos into one singular photo, which will show you star-trail beautifully.

1.5.2          StarStax

Once you have downloaded StarStax then follow the following guidelines to compile the photo:
1.       Open StarStax
2.       Click on File -> Open Images menu option
3.       Select your folder where all the photos are
4.       Click on Build->Star Trails menu option
5.       Select the radio button “Lighten-Screen-Blend (LSB without gaps, slower) option
6.       Click on OK
7.       This process should take approximately 5-10 minutes – thus go and have a cup of coffee
8.       When done then save your image to your hard drive
9.       Enjoy your photograph J

 Hope fully this article will de-mystify time-lapse star trail s photography, and make it a lot easier for you. As always please contact me if you have any questions or queries – and I will gladly assist you

 
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