Photos of the starry sky typically fall into one of the two categories:
- stars where the stars and the galaxy are sharp,
- star trails where the the apparent motion of the stars is captured.
EquipmentFirst of all I need to write a few words about necessary equipment. You will basically need 3 things:
- fast wide-angle lens - the reason you will need wide angle lens is because the longer the focal range, the shorter the time in which the stars are points - i.e. don't become star trails. With a 50 mm lens (35 mm equivalent) you will have a maximum of around 30 - 40 seconds before the stars become blurry. Therefore the wider the lens, the more time you will have. Why the lens should be fast? I think that this one is quite obvious - the faster the lens the shorter time will be necessary to correctly expose the photo (so instead of 40 seconds you will be able to use 25 seconds for instance).
Note that most of the time you will shoot wide open (more about this later) so it really makes a difference whether you use 16-35 f/2.8 lens or 17-40 f/4 lens. For all my recent astrophotos I used Canon 24 mm f/1.4 at f/1.4 which is one of the fastest wide-angle lens available on the marker. As you may notice I was using 10 seconds exposures. This means that when shooting at f/2.8 I would need to use 40 seconds exposures! So the lens makes a terrific difference. Please note that if you have f/3.5 or f/4 lens you can still take good photos but you will need to use longer exposures.
- steady tripod - this one is obvious I guess. You will shoot long exposures so any shake due to the wind or shutter being released might ruin the photo.
- remote release - same as above - this should be pretty clear. However, as described in one of my previous posts I don't use remote release at all recently. What I do instead is to use bulb feature of the Magic Lantern + 2 seconds delay.
Another useful accessory might be additional batteries. When you take long exposures and also it's quite cold (nights are usually much colder than days) the battery drains pretty quickly. So in order to have enough power for a whole shoot make sure you have more than one battery and that all of them are fully charged.
Another thing you will have to avoid is moon. Although it's beautiful it makes stars fainter than they really are. So take your star photos when there is no moon or when there is new moon (avoid full moon at all cost).
- disable Image Stabilization on your lens (or body)
- switch to manual focusing
- switch your camera to manual mode as you will definitely need to set exposure manually.
- set aperture to the widest one (as you will most probably focus on the infinity so the depth of field will be huge) unless your lens is really blurry when it is wide-opened. If so stop it by 1 - 2 EV.
If you decide to focus on the stars you will need to set your focus to infinity. Word of warning here: to get sharp photos you don't want to set focus to the point where infinity symbol is drawn on your lens - it hardly ever matches infinity (most often it's a little before or after that point). If you use Canon DSLR you can use Magic Lantern which I already mentioned in this post. Set L.V. display gain to some high value (like +5 to +7 E.V.) and also set ISO to eg. 3200 (or more). Then switch to the Live View mode. Everything will be very noisy but you will be able to see stars somewhere between the noise dots. Zoom in and move focus ring until stars become points. If you don't want to use Magic Lantern or don't own Canon's camera take a few test shots until you will have ideal focus. Just a tip here - take your shots at highest ISO possible (even if there will be a lot of noise). This will make exposure times shorter and will therefore increase your efficiency.
I could write exactly the same regarding composing your photos. You either need to compose, take a test shot, recompose, etc. until you have desired framing or use Live View mode with Magic Lantern. The second one is definitely easier but it's up to you.
|I took several exposures to capture more detail and colour|
and then merged the photos using blending modes
- Increase clarity and contrast in Adobe Camera RAW or Lightroom.
- Decrease exposure of the foreground a little bit (eg. by 1/3 or 2/3 EV) to make stars stand out more. You can use gradual filter in Lightroom or ACR for this purpose (or use one when taking a photo).