This morning I changed the spark plugs on my 2008 Touring Prius. Car is at 128,000 miles. As I placed the old and new spark plug on top of the air cleaner (to take a comparison picture) the phone's camera-image began displaying vertical lines, scrolling across the screen from left-to-right. I have posted a snapshot of this. The vertical lines could have been much more pronounced but I backed the camera away to try and get a balance of spark plug and interference. Edit: The light source is an LED flashlight held by my son about 4 ft away. The Hybrid battery pack is several feet away from the hood area. The closer to the camera got to the air cleaner, the more pronounced the interference is.
They are the double vertical lines which are more pronounced on the left side of the picture. No, the car was not on. I was changing the spark plugs.
It's not necessary to change the spark plugs just to demonstrate your kid's strange LED flashlight issue... First step is the state of charge of the flashlight. Put a fresh set of batteries in there and see if it works better. No need to remove spark plugs this time.
It is most likely a strobe effect between the pulsed LED flashlight and the electronic 'shutter' (image sampler) of your camera. Nothing to do with the Prius. Try a different flashlight. An old fashioned incandescent flashlight or ordinary daylight should get rid of it completely. Or even just change lighting conditions, which will change the camera's exposure setting.
At least you already know you don't need to replace the spark plugs to take the picture. It's way easier for you than the OP.
