The expression on that monkey is priceless!
Also like the shot of the monkeys sitting looking for the tourists - them looking at us, looking at them...
My technique for long lenses it this:
I take the focal length of the lens, so 200mm in this case, double it, so that makes 400 - then go into shutter priority mode, Tv, and set the shutter speed to 1/400 sec.
This speed of shutter will avoid camera shake or camera movement blur in your shots, and that formula works for any tele lens.
So a 300mm lens will need 1/600 sec, a 400mm lens will need 1/800 sec etc etc
Then I play with the ISO setting until I get a decent aperture for that shutter speed when shooting - ideally I'm after f8 - so I keep upping the ISO until my chosen shutter speed gives me f8 when I point the camera at the subject.
You don't have to have f8 of course - you could go for less depth of field with a smaller f number.
Using this technique I've waved tele lenses around after high speed cars and jets, and got sharp shots - it's a great place to start when shooting with long glass.