My girlfriend and I will be going on a 3 day/2 night safari in Kenya (Masai Mara). I'm looking for an inexpensive way to upgrade our equipment in the best way possible. We know next-to-nothing about photography.
She has a Canon EOS Rebel Ti1, with just the standard lens (18-55mm). I have an iPhone and a broken Canon S95 (it takes photos, but most buttons don't work so it's stuck on a lot of settings - no flash, for example, but it can zoom).
First for her and her SLR:
I assume we'll need some kind of zoom capabilities. I was looking at lenses like this 75-300mm which at $109 seems very inexpensive. I assume that 300mm will get us close enough, but I am completely confused about things like EF vs. EF-S, image stabilization (needed?), etc. I'm also confused about why a seemingly identical lens can cost 5 times the price. (That's one of my biggest questions!) Would that lens (the first one I linked to be appropriate).
Also I'm concerned that this is not versatile enough - will having this zoom lens all the time prevent her from taking photos of things that are closer to us? Or is 75mm "close" enough?
I'm considering getting something like the Canon SX510. From what I hear, it's so cheap because it will be awful in low light. But it has 30X zoom, and the majority of what we see will be during the day, and some of the reviews on Amazon say it's good in low light. Is there something else I should consider? This ($200) is the price range I'm looking at. I hate big cameras and there's a good chance I will never touch this thing again. If it can't fit in my pocket comfortably, I'll never use it - so you should assume this will be solely be for this trip (and maybe something similar that would happen once every few years). I could go significantly higher if there was something that had serious zoom and was tiny.
That's some background. I guess I could sum up the question as "if I have a SLR with a 55mm lens, what's the best way to get TWO safari-worthy cameras for $400 or less?"