Hello Marirenwick,
To clarify, are you using an iPhone 6 with iOS 11 installed or does this behavior occur with a newer model and iOS version? If you're using iOS 12 or later, you may want to check your HDR settings:
"HDR (high dynamic range) in Camera helps you get great shots in high-contrast situations. iPhone takes several photos in rapid succession at different exposures and blends them together to bring more highlight and shadow detail to your photos.
By default, iPhone uses HDR (for the rear camera and front-facing camera) when it’s most effective. For best results, keep iPhone steady and avoid subject motion.
Turn off automatic HDR
By default, iPhone automatically uses HDR when it’s most effective. To manually control HDR instead, do the following:
- On iPhone XS, iPhone XS Max, and iPhone XR: Go to Settings
> Camera, then turn off Smart HDR. - To turn HDR back on from the Camera screen, tap HDR, then tap On.
- On iPhone X, iPhone 8, and iPhone 8 Plus: Go to Settings > Camera, then turn off Auto HDR.
- To turn HDR back on from the Camera screen, tap HDR, then tap On.
- Other models: Tap HDR at the top of the Camera screen, then tap Off."
Click here for more details here: (select the iOS version that is installed on your device)
HDR camera on iPhone
We hope this helps.
Take care.