My wife & I both have the 4s & lately both phones have started to arbitrarily dim the brightness of the screen having nothing to do with the 5 minute "auto lock" setting. Is there a fix for this or a symptom of a bigger problem?
Is your brightness set to auto? If so you will see your screen go dimmer or brighter if it notices a change in ambient light. For example if you have your finger over the sensor or move it to where it has more light in the screen. Try turning brightness auto off and see of it still happens
I've had it happen a few random times & my auto brightness is off. For some reason the screen goes dim to where everything is just barely visible. I just lock it & unlock & it's good after that. Must be some sort of bug somewhere. I have iPhone 5 so it must be a software issue.
My 4s used to do that. But after awhile it stopped and has worked fine with auto brightness on ever since. I think I may have calibrated it somehow. I believe there was an article on here or somewhere else that showed me how. That may be what fixed the issue.