I do most of my picture taking outdoors while hiking. In my experience, the best answer is a decent day pack, having nothing specific to do with photography. When you're going for short distances and times, this stuff doesn't matter much anyway. When you're out there longer, then you always need other stuff along with the photo gear.
The hiking community has long ago found ways to comfortably bring "stuff" along. It really doesn't matter whether that stuff is a windbreaker, extra sweater, two liters of water, etc, or a few camera lenses. The method of being able to carry it all comfortably is the same.
That said, there are some differences between camera gear and other stuff you would bring in a day pack for normal hiking reasons. Camera gear is generally denser, ridgid, has hard edges, and more fragile.
There are two basic options for bringing stuff with you hiking:
- Day pack. These have straps over both shoulders, the weight is carried by your shoulders, and the pack rests up against your back. I consider this the preferred solution unless you need to bring unusually heavy or bulky stuff. I'd say these are good for up to 10 pounds or so, but of course that depends a lot on you too. I am basing this on having carried a gallon of water (8 pounds) with a little additional stuff, and that was about the limit for my normal-sized day pack.
Nowadays, these all come with padded straps. These are wide to spread the load on your shoulders. But instead of being just webbing, they are hollow with foam inside. That does help to keep the strap from digging in to a particular part of your shoulder. Again, you'd have a hard time finding a reasonable pack today that doesn't have these.
Particular for camera gear (ridig, hard edges), make sure to get a pack with a foam layer against your back. That adds very little weight, but helps a lot in keeping a hard edge from uncomfortably digging into your back. If you are doing anything more than a short hike, you're going to bring other stuff anway, like a windbreaker at least. Use the other stuff as extra padding to wrap the camera gear in. That not only makes it more comfortable to carry, but it keeps multiple lenses (for example) from rubbing against each other, and protects them a little more when you set down the pack.
- Overnight pack, sometimes also called a frame pack, although the two are not necessarily the same. Most frame packs will be overnight packs, but not always the other way around. In any case, these are bigger and intended for more bulk and weight that then basic day pack design allows you to carry comfortably and safely. The main ditinction is that the weight is mostly transferred to your hips, with shoulder straps more for ballance and keeping the pack from flopping around. Your back only touches the pack itself. In most designs, especially with the true frame packs, there is actually a gap between the load and your back. Rigid objects digging into your back aren't a issue, only the pack does that.
These packs are designed for strapping on additional items externally. If you're going to go so far as to take a tripod, you probably want to take a pack like this. Due to the larger capacity, both volume and weight, you can bring more lenses and the like.
The downside is that these packs make you feel more encumbered, aren't as quick and dirty like a day pack, and take more time and hassle to take on and off and to adjust just right.
What I do most of the time, even on all-day hikes, is to take a decent day pack. There must be enough room in the pack for all the gear in case you need it there, but most of the time I keep the camera (with one of the lenses of course) around my neck and one shoulder. Hiking with a camera just around the neck doesn't work. It bounces around too much and gets uncomfortable fast. Around the neck and one shoulder works well because you can carry the weight that way easily, it doesn't flop around, but it's still quick and easy to grab and bring it up to your eye.
The pack is then mostly for all the normal hiking stuff (water, wind breaker, etc), plus additional photo gear. With the camera outside the pack, the extra photo gear is then usually just one or two additional lenses.
I wrap each individual piece of photo gear in its own plastic grocery bag when it is in the pack. That gives some minor protection against dirt and wetness, keeps multiple items from rubbing up against each other, but without taking significant space or weight. Special bags or carriers for individual lenses are more trouble than they are worth. They only fit a particular lens, are often bulky, and sometimes it's actually not that easy and quick to get the lens out or put it back in. The nice thing about grocery bags is that they are interchangable. The lens that comes off the camera goes into the bag the new lens came out of. It's quick and simple. You can also set them down onto possibly moist soil without harm.
As I said, most of the time you want to keep the camera ready for use around your neck and one shoulder. However, there will be times when you're done taking pictures for the day, you just want to hike, it's late and the focus is getting back to the car before dark, it's raining, etc. Those times you want to toss the camera in the pack too. These situations come up whether you planned on them or not, so the pack always has to be sized for all the gear. That also means you have to have another plastic grocery bag for the camera.
I would start out with the day pack method on a few smaller hikes so that you can tune your system. Only you can ultimately say what you are comfortable carrying, although it will take some experience to arrange things optimally and thereby get the most comfort for the most stuff you can bring. Don't expect this to happen after just a couple hikes. Do a few local hikes where you can easily abort back to the car when things don't work out right. Try a all day hike, but locally where you can quit easily when needed. Realize it will take time and experience to tune your system.
One you are reasonably comfortable with the day pack setup, try to set up and tune a frame pack system. Again, this will take time and experience. Expect the first few outings to be uncomfortable and not work out right. On these, you can bring more stuff, like probably all the lenses you have, maybe a flash for macro shots, and a tripod. You will probably have to experiment with strapping the tripod, or possibly even putting it inside your pack. Tripods are a hassle when hiking. It will take some tuning to find a system that works for you.
However, don't let any of this scare you. Taking pictures in the wild away from people can be a rewarding experience and can yield great pictures. I don't mean to make it sound like it's difficult to do, since it's not. It does take some tweaking and experience to find a system that works for you with the tradeoffs of comfort, flexibility, safety, and photographic capabilities that you will like. Everyone is different.