hi all , am still beginner in this type of photography , i saw many shots for the stars within the city or as landscape shots , i watched and read some tutorials to learn how to capture such shots , but still couldnt achieve it , whenever i use high iso , 3200 for example , f/3.5 and 30s shutter i still get white pic , without any details , so is there is any clear tutorial that i can learn from ?
does any one have a pic showing the stars before blending it with another shot ?
thanks for helping 


