IPhone Problem while wanting to take picture camera is black screen?

Hello. I have not the newest iPhone but the one before that I think 3G, and I know that before when my phone had zero space available when I went to use my camera after I went to the camera the screen where you see what picture your taking is all black. But I updated and cleaned out my phone and I'm still having that problem. Please Help! I'm missing so many photo taking oppurtinities.
When the screen is black and sometimes even the shutter won't open. All the buttons are there so it's not totally black but when the shutter does open it is black. Not able to take pictures.
I have tried to reset it by pushing the tip button and the round one but still noting. I have tried turning it off for an hour but still nothing.
I'm super lost and have no idea what to do. Any help would be greatly appericated. Thank you in advance.

I'm not exactly sure what you mean
But twice before I have went to take a photo on my IPhone 4s and it stayed on the screen before the grey part opens
And just freezes then goes black with a swirly loading thing
It would do that until my phone died
Well I just held down the button where you turn your phone on and off and the home button at the same time (round button) until a apple logo pops up like when your turning it on
It's then re-booting and you just wait and it'll eventually come back on
Hope this helps