I have tested a coronas on a quite big maps and found that they disappear if you are too far away from them. Is there any solution to prevent them from disappearing, but still keeping aproximately same size, without blinding the whole screen?
Thank you for any help 
this has to do with your video settings in game. In Settings->View you can turn coronas off and change there distance.
yes but since everyone can have the own settings for this there is no way to guarantee that people are seeing what you want them to. all that you can really do is make the map as you intend it to be played and if people chose to turn down the graphic settings then that is there problem