The story about vibration is a myth!
I have found through 58 years of riding and taking a camera with me is so long as the equipment is in a padded bad which would protect the camera etc in the event of coming off. I have never had a problem. The days of taking everything including the kitchen sink, for me are long gone, My normal kit when touring Europe is one SLR body with a w/a to tele zoom fitted and a tele zoom as a back up. Currently these are a a Nikon 24/120 and a Nikon 70/300. It matters not if it is a film or full frame digital. I alternate with both. I also have a Fuji X20 as a backup with it's very handy 28/115 (equivalent) zoom. On odd occasions I also take a lightweight tripod with B&S head but have very rarely used it.
I have learned that carrying the absolute minimum you can use is far better. Stopping to take pictures is far easier if you can get to a camera and lens than faffing about trying this, that, or the other. It just doesn't work!
My bag is carried on the pillion seat using bungee hooked elastics to secure it in place. I have never had a failure yet. That avoids any injury by carrying it in a rucksack on my back.
Carrying anything solid on your back when riding is risking serious life threatening or crippling spinal injury should you come off. It does need to be waterproof or have some means of making it waterproof.
Tank bags are in some cases not secure enough to hold a bag in place with expensive and in some cases weighty gear. Probably the most secure way is to have a lockable top box fitted out inside with custom made foam padding to fit the equipment. That way it is safe to carry and moderately secure should you want to stop for a meal or comfort break.
In the event this is my take on the subject and it may not be everyone's ideal. The best way is fitted out top box to carry everything photographic. but when I go away I carry so much other stuff that space becomes a premium with clothing for 2 weeks or more so I revert to the bag on the pillion seat held by bungy straps.
This picture of my previous bike a BMW K1100lt just before I set off in June 2016 to head towards the Austrian Tyrol and Switzerland. I was camping in those day but no longer do it. The bike has to be meticulously loaded so it is not imbalanced. Trying to manhandle nearly 1/4 of a ton if it falls over isn't easy especially if the 22 litre tank is full . I also have to take tools and certain number of items I may need, 'cos on long trips you are largely on your own and in the event
of a minor break down you can be self sufficient.