Unfortunately DEET is one of the very few, if not only, substances that really keeps insects like (malaria) mosquitoes away. So if you are traveling to areas that have malaria, please do use repellent that contains DEET.
But keep it away from your fingertips when touching any equipment with plastics. I had my fingerprints "burned" into a camera too on one of my African trips. These days I usually put some repellent on my hands and then wash the inside of my hands before touching any equipment.