About QUALITY, I really expect lower quality or lower light with a large zoom (18-250) than a smaller zoom or even a fixed fov lens. I had in my old film SLR a 28-200mm (an "wow" on those times!), made by an "alternative" brand, and knew it had lower quality than an original and lower range, but I played a lot with it due it's flexibility and the fact to be always there!
The questions are:
1 - Is the loss of quality (or light) so relevant to make it unusable?
2 - Is the loss of quality (or light) so small to allow I to buy ONLY this wide zoom lens, and do not buy a 18-55 to the indoor meetings I want to shot?
I need a SINGLE lens starting in 28mm eq and going far tele to use in tourism, landscapes, artistic and familiar use, without the need to carry 2 or to exchange in each scene. This is a not so critical situation. The question is IF I NEED the other one (18-55) to shot the events - will it make such difference?