I have a Canon 7D and often take my camera on the road while traveling. In the past I've taken my Sigma 17-70 f/2.8-4 and my Canon 70-300 f/4-5.6, which means that I must switch out lenses quite a bit, depending on what I'm shooting. I get a much better overall image with the 70-300, but the 17-70 gets the big picture. Should I invest in a third lens for better travel portraits, close-up lenses to save space, or just a better lens overall (such as the Canon 24-105 f/4L)? I do love having low f stops for great focus and blur, but I also like having options, macro equipment, and reach. Perhaps there's no easy solution, but what would you do to travel relatively lightly in such a situation? Thanks!
You have performed a pretty thorough analysis of your predicament, and after sitting here for a while, an analysis is all I can really come up with myself. It is a tough predicament, wanting to have your cake, and eat it too. I have ONE recommendation to offer, that may help, or may not, and really isn't an ideal solution...but at least it is a one-lens solution. Its an expensive solution, and I can't say whether it is a viable option for you.
I would look into the Canon EF 28-300mm f/3.5-5.6 L IS USM lens. This lens was essentially designed to solve the particular problem you currently face. Its an expensive solution, but its a quality solution, as the lens is top-shelf. Being an L-series lens it uses the best glass available, and brings all the luxury bells and whistles to the table, including ring-type USM, image stabilization, and a zoom range to die for. The lens is heavy at nearly 60 ounces, but it would be the only lens you need to cover just about everything you can imagine outside of those ultra-wide angle scenes.
There are some alternatives from third-party vendors, such as Sigma's 50-500 f/5-6.3 EX DG HSM lens, that may also fill the role of "one lens to rule them all", and at a better price point. I think you lose out on the wide angle in most cases, and gain on the long end, which might not be ideal for travel. Again, not really a perfect solution...as you still have to lug around a fair amount of weight...but you don't have to carry multiple lenses or bother with changing lenses while out and about. You might take on a few extra orders of magnitude of "nerdy tourist" as well...however there are always trade-offs to be made. ;)
If your price isn't as unlimited as the Canon EF 28-300mm f/3.5-5.6 L IS USM lens that jrista pointed out, you might want to look at the Canon EF-S 18-200mm f/3.5-5.6 IS Lens. It only weighs one third of the weight of the giant beast, and still gives a huge range. This lens is designed for the APS-C sensor that your 7D has. Just yesterday Canon Europe actually announced a 2nd version of this lens, so if you are thinking about buying one you might want to hold out for that version.
The right answer is going to depend heavily on how you like to travel. If you are traveling out of your car and don't mind the weight, then extra lenses for different purposes would be the way to go. If you want a light kit that does it all with a single lens, keeps you mobile and ready for the action, an all in one solution like one of the lenses above might be the best.
You said you want to travel relatively lightly, so I would consider something like the 18-200mm lens, with maybe a single prime lens either in the 35,50,85, or 135mm range. This will give you a light, small, fast(large aperture)lens to blur the background and shoot in low light situations that the 18-200mm lens will not perform as well.
Best case scenario in my opinion while considering price/performance/weight/and quality:
I asked a similar question here a few weeks ago, limiting the question to 1-3 lenses, while giving quality the highest value of importance. Price was not a factor in my question at all. You can see that question and its answers here.
I'm going to give an alternative answer.
Instead of taking everything, or a lens designed to everything, decide on one lens to take on a given trip, and try to see what you can do with that.
Sure, you'll miss things, but, there's a lot of world out there, and a lot of missed shots. Focus on what you can get with that lens, and if you have an idea for something that you can't make work with the equipment you have with you, maybe make that the focus for the next trip.
There's several benefits to this approach:
It might be helpful to think about "traveling lightly" vs. "minimizing lens switching" separately, even though they seem to be one in the same goal. As jrista pointed out, there's at least one lens out there that covers a really nice focal range with "L" quality, but it's hardly a lightweight option. Personally, I think that by the time you load up a 7D with any sort of zoom lens, plus a handful of extra batteries, cards, and so on, you're really pushing past "lightweight". In fact, if you were to grab that 28-300 lens, I'd bet you'd be close enough in weight to the two lenses you've got now that you wouldn't be gaining much in terms of weight or space. If your real goal is to minimize lens switches, then this might very well be the right approach for you.
On the other hand, if you're really trying to save weight, I'm not sure there's an all-in-one lens that saves space and weight and offers quality worthy of a 7D. Maybe plan-B is to rent a 4/3 camera or something. When I bought my DSLR, I hung on to my old superzoom P&S for exactly this sort of dilemma. I don't plan on leaving the DSLR home until I get up to at least a four or five-day backpacking trip, but at that point, I think I'll be pretty happy to leave the weight behind.
With your current two lenses, you have to switch to go either side of 70mm, which to me seems quite a good switching point. But if you find you're switching lenses too much, then perhaps you'd be better off (as far as reducing switching goes) getting another lens rather than one less.
For example, if you added a Sigma 50-150 f/2.8 to your kit, you'd have:
now with quite a bit of overlap in each case so you are perhaps switching less often.
Some other good options to cover the switching range would be:
Of course you're then carrying some extra weight, but it could give you some hysteresis in your switching, which will mean less back-and-forth between lenses.
That said, if you're mostly using the extremes (17-24mm and 200-300mm) then this won't help at all!
If you're worried about the sharpness of photos, or other issues with image quality, then you won't want to get an all-in-one, and the only such options only go down to 18mm anyway. So that option can probably be ruled out if its the extremes that you really want to or really enjoy capturing.
I found myself switching lenses a lot travelling recently, mostly because I was enjoying using the really wide angle of my 10-22mm and the longest lengths of my telephoto zoom. Even though I used a 17-55 a lot more than either, I had more fun with the extremes. So if you're like me in that regard, then it might be worth considering a second body (one for each lens) rather than one fewer lens. This is obviously not a cheap route, and may make carrying your cameras more/less awkward, but definitely worth considering, if only briefly (:
For what its worth, I've not convinced myself its worth doing (mostly due to cost), but I'm always reminded of a photojournalists stories I read a while back (forgotten who exactly), who for many years had two 1D bodies, one with a 16-35, the other with a 70-200, and they pretty much stayed on there for years on end (I think he had a 50mm f/1.4 that would very occasionally come out of the bag). Where you or I would have switched to a mid-range zoom or prime, he'd take a few steps forward/back (whichever was more feasible) and reach to the left/right shoulder where the appropriate camera/lens combo was resting.
You should remember that you are taking travel pics because you are travelling, not travelling because you want to take pictures. Any sort of fatigue will be evident in your pictures so you absolutely have to travel light, so just give up the idea of travelling with everything. Personally I don't prefer the image quality of super zooms (18-xxx lenses). What lenses you choose depends on the place you are visiting:
Depending on the place you go to, pick the lens best suited for the place and one lens that you use as a walk-around lens. These should be good enough. You could also lookup pictures taken around the area you are visiting on flickr maps, decide what kind of shots you want and take the lens that'll help you get the shots.
True, you are taking pictures because you want to capture a journey. You are not travelling for photography and for that I use Tamron 18-270 all in one lens. Picture quality ise really nice and I can use this lens for almost all type of pictures.
"When you can't be with the 1 you love, love the 1 you're with." Sometimes, when travelling with my 30D, I elect to go out from my hotel each day with a different lens- a 17-70 one day, a 50mm prime the next or a 100mm prime, sometimes the 18-200. I aim to enjoy each and every experience, and shot.
I was recently out in the field with only the Canon 70-200 f2.8 with the 1.4x extender. I had about a half mile hike to get to where I wanted and I didn't want to bring my wide (and heavy) L-glass. (Did I mention I was hiking before sunrise?)
Anyway, of course the shooting plans changed when I got on site and I needed wider glass. I didn't have caps with me to take off the extender and I didn't want to since the scene was changing so fast.
So, what to do? I stitched together 4 images and Photomerged them in Photoshop. Now, I won't say this is a perfect substitute, but hey, it got the job done for me.
BTW, the original is 6800x5400 pixels.