What is ISO and How Does it Influence the Images in My Drone Survey?

ISO can make images taken in low-light conditions appear brighter without sacrificing a fast shutter speed. This article takes you through some examples of what impact the ISO has and when you need to look out for it.

The recommended ISO for sunny weather (optimal flying conditions) is 100. When shutter priority is chosen as the capture mode, the ISO (and aperture) will vary to guarantee we can get a fast fixed shutter speed and thus capture sharp images.

A high ISO can cause accuracy issues when being processed due to the increased noise in the source imagery. Some cameras can support a higher ISO value than others. If you are using a Phantom 4 Pro or RTK it is best to keep the ISO below 400.

Common Question: Why is my ISO so high and blocking my upload?

Assumptions: Phantom 4 Pro or Phantom 4 RTK (can be valid for other drones as well) with Shutter Priority mode turned on.

1. Auto ISO has accidentally been turned off and a higher fixed ISO is applied. This happens often when a user is setting up the drone in the office and the ISO button is bumped. Check that the ISO is set to Auto (for the P4P and P4RTK this will be denoted by a blue circle instead of a grayed out circle).

2. The conditions are too dark for the given shutter speed. If it is really dark, come back another day.

• To start with, you can reduce the shutter speed gradually to get the ISO to come down to 100, however, your aperture will be wide open (f/2.8) on Shutter Priority mode. 
• Be careful that the motion blur does not get too high; if it increases over 20mm you should decrease the flight speed for the P4RTK or use hover and capture for the P4P. 
• Winter is the most common time for high ISO issues to occur, we typically recommend a shutter speed of 1/1000 where lighting conditions allow. In winter you may need to reduce this to 1/800, 1/640, 1/500 to allow enough light to hit the sensor. Remember to fly slower if you are reducing the shutter speed lot.

3. Very fast shutter speeds like 1/4000 → 1/8000 to fix motion blur issues. It may seem that if 1/1000 is good to reduce motion blur then even faster is better. This can catch people out as the really fast shutter speeds can have worse negative effects than benefits.

• Shutter speeds this fast do several things. The aperture will become wide open at f/2.8 to allow as much light in as possible, resulting in less than optimal sharpness.
• The ISO will increase a great deal to make the image brighter at the heavy cost of noise and noise reduction artifacts. 
• The electronic shutter will turn on at speeds greater than 1/2000. Keep the mechanical shutter turned on.
• The pilot should reduce their shutter speed to approximately 1/1000 depending on the conditions (a bit slower in low light conditions).
• Ideally, the ISO will be 100 and the Aperture will be f/4-5.6.

4. The user has accidentally enabled Aperture Priority or Manual mode and locked the aperture at f/11 or similar.

• On Aperture Priority mode, this will cause the shutter speed to drop causing motion blur and the ISO to increase causing noise.
• On Manual mode, over and underexposure is likely, depending on the other settings.
• Aperture values like these also cause diffraction artifacts to occur that further reduce the image quality.

What happens if I have a camera that can produce good results with a higher ISO but the uploader is blocking me?

Please open an Intercom chat by clicking on Support > Contact Support and report the issue to our data team. 

They'll be able to help you upload the data and will report it to the team to analyze the dataset and update the validation for that particular system.