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| A DJI Mavic 3 drone photo, taken above the Outeniqua Pass foothills in South Africa by Agnieszka Taggart |
Written by Agnieszka Taggart
Agnies is a licensed drone pilot and instructor in Johannesburg, South Africa.
Drones are becoming more popular among photographers so it’s no surprise that with the improving specifications, they are also becoming usable in night sky photography.
There are couple things to consider though.
One is the legal side of flying drones at night as some countries only allow drones during the day or with special permissions.
The second one is drone capability to take long exposure photos. Modern drones are quite good at holding the position, but what’s considered good in the world of drones, may not always be good enough in terms of optics and photography.
Typically, the longest exposure from a drone is 8 seconds, but it does not mean that all your exposures taken at 8s will be usable - this is to the fact that even within this rime, the drone will have some movement, usually caused by wind.
Drones typically use the below systems to hold the position:
- GPS: modern drones use as many satelites as they can detect, 12-15 satelites is needed for good position lock, sometimes even more. Accuracy increases with number of available satellites
- Compass/ gyroscope: this defines which way the drone is pointing
- Visual sensors: many drones are equipped with visual sensors for position hold. The sensors scan the ground and register the image - the more contrast and illumination, the better the visual position hold.
In order to get good position lock, hover over something bright and with good contrast - you might want to put a torch on a landing pad.
Accuracy of visual sensors decreases with height, so do not fly high if you don’t have to. In most cases, you only need to clear the height of the roof and trees, so 10-15m above the ground should be enough. Wind is also weaker close to the ground and increases and often changes direction as you mice up.
* Do not take off from a car roof, there is a lot of interference from car electronics that might affect the accuracy of the drone compass. If you chose to hover above a car, take off from a different spot and move over once you reach required height.
Based on the above, you might need to adjust your regular work flow for all types of night time photography.
1) Single exposures
As mentioned, you will be limited to 8 seconds. That’s short, so in order to have usable image, you will need to dial up your ISO. I typically use ISO3200 on my Mavic 3. In case of single exposures, sensor size is the key. You might get away with 1 inch sensor, but 4/3 will produce better results. Take many shots and choose best - they will not all be usable. The types of photos that work well in this situation are naturally contrasty and well illuminating landscapes (snow, sand, water, pale rocks such as sandstone and dolomites), landscape with busy road to capture the trailing lights and non-aggressive light painting
2) Blending and stacking
Typically you would take some shots at “blue hour” and then some night sky shots later. With this technique, it is critical to keep the drone in same position. It is extremely unlikely that you will do this with a single battery, so you will have to record the exact drone position, direction and height. You may want to create a waypoint if your drone app has this function.
3) Composites
Using drone for night time photography is challenging and you may be left with no option than to create composite. If you do, make sure that it is true to nature - check the directions and star positions. It is useful to take a shot with most prominent stars and combine it with shots from the ground. And of course ALWAYS reveal the technique.
