Share your experience!
The camera does not work, it throws error
can you describe what error the camera is having?
try to clear camera app cache.
settings>app>camera>clear data>restart your device
also try on safe mode
Hi @brenditaloza, I'm sorry to hear about this. 
As @nolramlb mentioned for us to be able to help you in the best possible way we would need some further information.
Do you get any error message when starting the camera application in your device? Was there any difference when you cleared the data for the camera application that @nolramlb suggested? This won't delete any of your photos or videos, it will only reset the data for the application.
If there is no change after clearing data I would recommend rebooting your phone in safe mode. Does the camera application work in safe mode?
Please keep us updated! 
Hi @Shen02, I'm sorry to hear about that. 
I'd recommend that you reset the data for the camera application, this will not delete any of your photos and videos. To do that, go to Settings > Apps > 3 dots > Camera > Storage > Clear data. Is the camera application starting faster now?
If not, please try and reboot your phone in safe mode and see if the app is starting faster when rebooted to safe mode.
Let me know how it went! 
Thanks for getting back to me!
I just tried to replicate this in an Xperia M4 Aqua with the latest software installed, and I was no able to replicate it. 
What I did was I started the phone > pressed the camera icon > pressed the home button and started the camera application again, then I repeated that 20 times. I didn't notice any difference in the time it took to start the camera application.
If you try the above and you experience that the camera app gets slower and slower to start, I'd recommend performing a software repair using Xperia Companion.
Let me know how it went and have a great weekend!
Hello again!
Glad to hear that there wasn't any troubles with the phone! 
The Xperia M4 Aqua supports SD cards up to 200 GB in size and it also support 3 types of SD cards (microSD, microSDHC, microSDXC).
I hope that answers your question! 