The Phantom 4 RTK does a good job producing high quality images, but in low light conditions you may find that the images are of a lower quality. Typically motion blur is to blame due to a slower shutter speed, to avoid this we want a fixed faster shutter speed. We recommend using the shutter priority exposure mode to achieve this.
Setting the Exposure Mode for a mission
- Turn on the controller and craft
- Tap on Plan, and choose a mission type
- Tap on Camera Settings on the right hand side
- Enable Shutter Priority
- Adjust the shutter speed to reduce the amount of time it takes to take an individual image. If you select 800, this means the images will be taken in 1/800th of a second. 1000 is 1/1000 of a second or 0.001 seconds. We recommend 1/1000th as a starting point for shutter speed. In low light conditions you may need to slow it down a little bit.
Flying at 10 m/s
Limitations and further explanation
Taking the image as fast as possible is not always the best solution. When we are using shutter priority mode we are locking one of the 3 methods that we have available to control the exposure of the image. The other two components of the equation (Aperture and ISO (for our purposes at least)) will need to work around the limits that we have imposed.
If the shutter speed is too fast for the lighting conditions we may see the aperture fully open (f/2.8) and the ISO, which can be seen as a sensor gain, start to increase considerably. The higher the ISO, the more sensor noise will be present in the final images. Although we can still process higher ISO images if necessary, we find the best results can be produced with images taken under ISO400, preferably at the native ISO100. For more information on ISO and how it affects the imagery you're collecting check out this article.
In Winter or in lower light environments you may need to reduce both your flight speed and shutter speed to maintain the same low motion blur as the brighter environments can achieve while flying faster.
Does the Aperture have an impact on the image quality? Yes, it does and it has a sweet spot for where the camera can take the sharpest images.
Max Aperture = f/2.8: As much light as possible is hitting the sensor in this arrangement. Fortunately the image is still clear enough with this camera with the aperture fully open, but it's not the best it can be.
F/4-5.6: The sweet spot, with the aperture "stopped" down to this point your images will be as sharp as possible with regards to the aperture.
Greater than f/6.3: As the Aperture is closed even more, diffraction can occur. We want to avoid this and as such suggest that you keep it more open than f/6.3 if possible.
I still can't do it!
We wrote these articles to arm you with everything you need to get the job done on your own, but we understand that sometimes this isn't sufficient.
If you're stuck, the Propeller tech support team may be able to help. You can contact our support team by emailing firstname.lastname@example.org.