I often get asked how to shoot a night sky / starry sky. I am not a specialist in this fields and there are better camera systems than the NX system to do astrophotography, but it’s definitely not impossible to do some kind of astrophotography. You can mainly do either star trails (capture the motion of the stars due to the rotation of the Earth) or you can simply shoot what you are seeing like in the photo below. With this article I will set the focus on the second alternative as star trails are a problem for newer NX cameras, but at the end of the article is a short round up about star trails, too.
The problems you need to be aware of
The most important factor is to find an area where light pollution is low. Light pollution means that the sky is brightened up by surrounding light sources. In areas with strong light pollution you can see much less stars than in an area without light pollution. The result will be a photo with a more or less a white and washed out sky. Actually it is not that easy to find good areas in Europe as density of population is quite high. People who watch the starry sky in a city will be really(!) impressed when looking into a night sky in an area without light pollution. During my journey to Australia I was in the outback far away from any urban light sources and was stunned by the beauty of the night sky. There are several websites on the web that serve maps showing the light pollution, even Google Earth has an overlay to show the light pollution. Find a good resource for your location and try to find a suitable location for your shooting.
Another problem is the moon. The best days to shoot the stars are the days around “new moon“. In other words: No or low light emission of the moon potentially enables you to take better pictures with more stars on it. The problem is that the moon brightens up the sky way too much and you have a similar problem as with light pollution.
The last thing you simply need to be aware of is the rotation of the earth. You can’t expose the images too long (except you want to do star trails) since you would get problems with the stars being shown as short strips. This influences the exposure settings you have to choose later.
What you need
So what do you need to take with you to shoot a night sky?
- Camera (e.g. Samsung NX20)
You need a camera with good high ISO capabilities. It either needs an integrated timer or a connection for a remote control. A swivel screen can be really handy, but is not mandatory.
- Wide angle lens (e.g. Samsung 16mm f/2.4)
The lens is best suited with a low maximum aperture and a low focal length (10-20mm).
- Remote control (if available)
If you have a remote shutter trigger for your camera you should use it. Alternatively you can use the self timer of your camera.
As you have to use slow shutter speeds a tripod is mandatory to avoid blurred photos. Make sure your tripod can hold the camera with the lens facing to the sky.
If you want to shoot a photo showing more than just the plain sky you need a (strong/bright) torch (or maybe a strong flash) to illuminate the subject. The camera light integrated in current mobile phones is usually not bright enough. Anyway it is a good idea to carry a torch when shooting at night. 😉
- “Equatorial” mount (optional)
There are devices that can be used to compensate the rotation of the earth. Those devices are called “equatorial” mount and they cost quite a lot (e.g. Vixen Polarie, about 400€). Therefore this is optional and I will show you the way how to do it without such a device.
Which settings to choose
After you arrived at your selected location you have to prepare your gear. Mount the camera with the wide angle lens on the tripod and, in case you own one, attach the remote control.
Now you need choose the proper settings. Some settings are described in depth in the Samsung NX Camera Settings Guide. You might also (re)read the Introduction to the basic concepts of photography. This might help you to understand the correlation between ISO, shutter speed and aperture which is useful to understand how you have to adjust the other respective values in case you are changing one specific setting.
- Mode (M)
Switch to manual mode (M).
- Shutter speed (about 30 seconds)
This is the most flexible setting, but it is bounded above. You should try to avoid a shutter speed longer than 45 seconds or you will slowly start see the motion of the stars. Try to start with a shutter speed of 30 seconds and adjust it later. You need to increase the shutter speed when using a slower lens or a lower ISO number and vice versa. Shutter speeds longer than 30 seconds can be used in bulb mode, but this only makes sense using a remote control as the shutter needs to be pressed during the exposure.
- Aperture (maximum aperture)
The more light you can capture the better. Set the aperture to the maximum aperture or stop down a bit to avoid vignetting and spherical aberration. I used the Samsung 16mm f/2.4 previously and tried both f/2.4 and f/2.8 but both apertures delivered good results. The Samsung 20mm f/2.8 can be used as well. Using the kit lens with it’s maximum aperture of f/3.5 or the Samsung 12-24mm f/4 you need to set the shutter speed to a much higher value. This can be problematic without an “equatorial” mount.
- Focus (Infinity)
This is tricky since you usually don’t have enough light to use the autofocus. You need to set the focus to infinity. There are mainly four options, which you should try in the following order until you found a working solution:
- Newer NX cameras have a “Smart Mode” called “Fireworks” which can set the focus to infinity. Additionally you need a lens that has a AF/MF switch. Change the mode dial to the Smart Mode (not Auto Mode!) where you can select different predefined shooting modes, e.g. Macro, Rich Tones or Fireworks. Select the Fireworks mode and press the shutter button half and a green focus confirmation will show up. The camera is set the focus to infinity. Afterwards change the AF/MF switch to MF and rotate to the mode dial to whatever mode you want to use (probably M).
- If there is any light source far away you can try to focus on this point. Afterwards set the focus to manual focus to lock it.
- If the previous failed try to set your ISO to the maximum value, turn on the framing mode and enable manual focus with the MF Assist setting set to “Enlarge 8x”. This is only for focussing and is needed to show you the stars as bright as possible on your display. Now try to focus until you see sharp dots or at least one proper focussed star. You can reset the changed settings (framing mode, MF assist, ISO) after you got a proper focus.
- In the case the previous methods fail you need to do some try and error on focussing, sorry. 😉
- ISO (1600)
Set the ISO number to a value which delivers barely acceptable image quality. Using the sensor used in the NX20/1000 I would suggest using ISO1600. With one of the newer sensors you might also try ISO 3200.
- Noise Reduction » Long Term NR (On)
Turn this setting on to remove disturbing image noise.
For star trails you would need to turn it off to avoid gaps in the star trails.
- OIS (Off)
As you have mounted the camera on a tripod there shouldn’t be anything to stabilise. On a tripod the OIS can lead to blurry images and therefore you should switch it off.
- Quality (RAW)
For astrophotography you should use RAW or RAW+JPEG SF. The camera applies noise reduction algorithms to JPEG files and this can be a problem as stars are similar to image noise. To avoid any noise reduction in camera you should use RAW. You can apply some slight noise reduction during development of the RAW files if needed.
Small hint for the swivel display: You can use it to change the latest settings, but before starting to shoot images you should turn it away from the lens around to avoid that the light from the screen is reaching the lens. This could influence the photo in a bad way.
What about the torch?
You can also include the surrounding into your photo as shown below. (Actually this image is not the best. It was quite windy and the tree is unsharp at some areas, but it is enough to give you a short impression.)
That’s where the torch might get in. Depending on the brightness of the object you want to have on your photo you might need to use the torch to lighten it. Just try to quickly light all areas of the subject once in case it is too dark.
What about star trails?
The problem with star trails using a newer NX camera is that Samsung restricted the bulb mode (can be found in M mode) to a maximum time of four seconds (minor problem) and additionally you can’t disable the Long Term NR for the bulb mode (major problem). This is a problem for shooting star trails as the photos are delayed in time. The cameras with the “old” 14 MP sensors (NX5, 10, 11, 100) don’t have those restrictions and additionally they have the possibility to use an external power supply. If you have one of those cameras (I bought a cheap NX100 for this) you can play around with star trails. The newer cameras like the NX30 have a feature for interval captures integrated. This helps a lot as you can recharge the camera via USB while shooting.
Star trails are nowadays made from many single shots and combined using image editing software later. There is a free software for this special procedure written from Achim Schaller. Visit his website startrails.de for more information.
Postprocessing the photo is optional and depends on your personal taste. I am using Lightroom for postprocessing and wanted to brighten my photo up a little bit. I increased the exposure, increased the whites, decreased the blacks and played around with the highlights.
I haven’t used noise reduction (luminance) in Lightroom as I want to avoid that the stars are removed as they are falsely detected as noise. You can carefully try to use the noise reduction sliders in Lightroom until the result is pleasant for you, but I would recommend to leave the noise as is.
The second photo was developed a bit longer as the tree was overall too bright. I added a partial brush for the tree and set the highlights for the brush to -100 and the exposure to -0,7. The other development settings are similar to the ones I used for the first photo:
As you can see the structure in the night sky has improved and the tree fits in better.
Have fun shooting the night sky and enjoy the “wow”s from your family and friends. 😉
By the way: There is an official introduction on this topic from Samsung as well: Photographing the night stars.