How to Photograph Star Freeze Photographs

Overview

Freezing stars is the art of taking photographs of the night sky with obviously a lot of stars in it. Stars can create awesome effects and mood inside your photograph. It is ideal to photograph Stars when there is no clouds in the sky and preferably no moon, and far away from city lights, as these environmental factors will reduce the amount of stars you can see in your photographs.

This article will show you how to photograph the Stars with the use of a tri-pod, your DSLR camera, a cable release and some patience.

Setting Up

This section will provide you with the technique for photographing the Stars. 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.    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, and
6.    Connect your cable-release to the camera 

Focusing

The next step is one of the most important parts: how to focus onto the Stars. 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 Stars 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 Stars:
1.    Set your lens to MF (there are two options AF (Auto Focus) and MF (Manual Focus)),
2.    If your lens have image stabilization, then switch it off,
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 Stars (see where there is the most stars in the sky),
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,
8.    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.
 

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.

Camera Settings

Overview

In the beginning it is difficult to remember all the camera settings, and hopefully this guide will make it easier for you to get to the right setting for your camera. 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 = 3200, Shutter Speed = 30 Seconds and Aperture f/2.8
2.    Press your cable release, and take the photograph
3.    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
4.    When the photo is finished then look at it in playback
In Playback make sure that all the stars 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. This is where photographing the Stars becomes tricky, and follows the following guidelines to correct the problem:
1.       Decrease your ISO from 3200 to 1600,
2.    Increase your aperture from f/2.8 to f/3.5 (maximum f/7.1),
3.    Decrease your shutter speed from 30 seconds to 20 seconds, and
4.    Take your photograph

Hint 1: If you want more information then please look at the rule of 500. 
Hint 2: Make sure that you do not change the focus of your camera. 

Compare then your two photographs, your second photo should not have the elongated stars when zooming in, BUT your camera now captured less light, and thus would look “dimmer” with less stars. Next we will look at what are the ideal settings into taking a Stars photograph 

Settings

Now what are the right settings into taking the ultimate Star Freeze photograph? Follow the following guidelines and you will be able to photograph brilliant Star Freeze 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 Star Freeze Photos:
White Balance (Tungsten), Aperture (f2.8), Shutter Speed (17seconds) and ISO (1600)
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