Why do I keep getting a white screen when doing long exposures , Please Help
Overexposure!, either lower exposure time, add a density filter, lower iso or increase aperture number, that should solve the problem.
Check your exposure compensation aswell just incase you have increased compensation value as this will blow out the images aswell, its easy to miss in the heat of the moment
Make sure in these situations, check your light meter That way you can see whether the environment is too bright or dim for whatever shutter speed/aperture you have set to.
If you are trying to take long exposure during daytime, it is best to invest in a ND filter which helps filter out a lot of the light.
If you want to do a really long exposure during the day you will most likely need a very strong neutral density filter. Think sunglasses for the camera. You can also stop down a lot to something like f/16 or better, but you might find you cannot stop down enough. The photo will not look quite a good when stopped down all the way either.