While shooting in dark, few elementary things should be set optimally to get well exposed frame. In the night time, the amount of light is tremendously reduces and it becomes difficult for even camera sensor to reproduce the scene. In such conditions, lens aperture should be kept at its widest value to let more light to enter. Frame can be exposed at the same time by boosting the ISO speed to an optimal value. Higher the ISO, brighter frame you get but with more noise on it. So, value of ISO should be chosen wisely.
Frame can also be exposed well by increasing the shutter opening time or simply taking images on long exposure mode. You need rigid support while shooting long exposure shots to avoid camera shakes and blurs.
So, a well and optimal exposed shot can be captured by doing proper exposure settings with wise combination of aperture, ISO and the shutter speed.
All above three techniques are often used in digital photography for getting optimal exposures, but have their own distinct drawbacks as well! Fore example; higher ISO, definitely brightened the frame but it is generating digital noise on the frame in the form of grains. Boosting ISO is nothing but the increasing gain of the sensor thus increased sensitivity. However, lens aperture allows amount of light to enter the camera but it affects the depth of the scene. Wide aperture value reduces depth of field for a particular composition. Slow shutter speed; however allows frame to get more exposure, but it makes camera prone to shake and produce blur images.
So, one can get better exposed picture by using combination of all these three techniques optimally and considering the subject being shot. For example, for low light landscape photography, combination of slightly boosted ISO, slow shutter speed and large exposure can give better results. For sure, tripod must be used in that mode. If the subject being shot is an insect or any tiny thing, you need higher magnification and good depth of field to get maximum things in focus. Lowest value of aperture will give the heights depth of field but reduces the amount of light in correspondingly. Result; under exposed frame and loss of auto focus capability. To get rid on it, you need to adjust shutter speed and ISO to in combination to lowering down the aperture value.
Following is the procedure and required articles to capture the star trails by using above mentioned techniques.
Articles required:
- Camera with manual controls.
- A sturdy tripod.
- Remote shutter release cord with shutter lock slider.
- Wide angle lance, 12-24mm etc. 18-55mm kit lens will work at 18mm.
Procedure:
- Set white balance to tungsten to get the bluish night sky.
- Boost ISO till 400~800 to get more details from the dark.
- Set image quality to RAW. It helps in post processing!
- Set exposure to 30 secs and shooting mode to continues shot.
- Put camera on tripod, set focal length at minimum.
- Connect remote shutter release cord to camera and switch on camera.
- Set the focus at infinity or try to focus a distinctly located prominent star.
- De-select autofocus and press the shutter release button and lock it.
- Take two or three long exposure shots and observe the movements of stars. It will let you know the direction of star’s movement.
- Accordingly, go ahead and press the shutter release button and lock. Keep the camera untouched for a long. May be for 2~3 hours.
- Camera will take 30 sec long shots continuously.
- Get around 250 to 300 shots with same exposure values and stack all them together by using Star Trail.exe software.
Hope this article will help you in order to capture beautiful star trails in the clear night sky. One suggestion here; try to avoid city lights, hence select a place away from the city.
Happy Shooting!
Gaurav Kavathekar
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