Hi, I did the 4 day hike in 2014 and can offer some suggestions. I used one weather sealed camera and short zoom 24-80mm equivalent for the entire trip. It was the perfect set up (I carried two other lenses that never left my duffel bag). Maybe an extra wide lens could be handy, but the zoom should stay on your camera full time. I also had 4 extra batteries and a back up power brick as there are no charging stations on the trail. Bring plenty of extra brand name memory cards, a blower and lens cloth. A mini portable tripod is useful, but don't bother with full size. You will not appreciate the weight and added bulk, and will not be allowed to use it at the Machu Pitchu site. Hiking poles are a necessity, as is a day pack with a Camelback style hydration insert. I wore my camera on a sling strap wherever we went. We never had any theft issues on the trail or in Cusco or felt threatened except maybe in Lima. Leave your jewelry and nice clothes at home-try to not look affluent and you will be fine both in town and on the trail. We used a Peruvian based tour company and the service was excellent. There is lots of information on the internet about preparation. Also, carry multi purpose antibiotic tablets just in case you pick up a stomach bug (in town); this will save you a lot of discomfort. Enjoy, it is truly a once in a lifetime experience.
I kept a photo journal of the trip. https://trankstertravels.wordpress.com/2014/08/31/from-cusco-to-machu-picchu-trekking-the-inca-trail/
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