If you were me, which lens would you buy? (24-105 vs. 70-200 f/4 IS)

[neuroanatomist]

Welcome, Matt!

And then hopefully they make the 17-40 in a IS variety by the time I'm ready to purchase my next lens

Well, if you're looking for quality glass with IS in that range, consider theEF-S 17-55mm f/2.8 IS USM, or if you want a true 'walkaround' lens and really don't mind a slow aperture, then theEF-S 15-85mm f/3.5-5.6 IS USM. Both have similar, very high IQ - the 17-55mm in particular is 'L-quality' (and L-priced, but without the robust build and weather sealing). The main downside to those is that they won't work on a FF body, so depending on how soon you plan to upgrade, that may be a show-stopper.


Personally, the EF-S 17-55mm is my most-used lens on my 7D.

At this point I'm leaning towards the 70-200.

I'd agree, in your case. I'd assume you're basing this on your current shooting patterns. I would caution you that while I think the 24-105mm is stellar on FF, the difference between 24mm and 17/18mm on the wide end is very significant on a crop body (24mm on a 1.6x body is pretty close to a 'normal' focal length. If you enjoy wide angles and sweeping vistas, you'll likely find yourself wanting wider than that (for me, even the 17mm end wasn't quite wide enough, so I also have the EF-S 10-22mm f/3.5-4.5 USM).

[mattyg1027]

At one time, the EF-S 17-55 f/2.8 IS USM was in this race, but I think I was scared off by the price vs. build quality (constantly read about dust issues), the (perhaps overly hopeful) thought that I will be upgrading to ff in the not to distant future, and the focal length range being slightly wide for most of my use. It would be great for indoor group pictures though, you should have seen me trying to take a picture of my family at the dinner table on thanksgiving with the 50/1.4. The tripod was in the other room, lol.


I really never gave that 15-85 much of a look, probably because of the slow aperture and ef-s mount. When I finally made the jump from the kit lens to the 100/2.8, I realized how nice it is to have that extra stop or two. I was actually wondering if the max of f/4 on the two lenses that I'm still considering would bother me, but I have decided that I have to make a sacrifice for the flexibility of a zoom in the price/size/weight that I find acceptable. One of the major reasons I like the fast aperture is the subject/background separation (because most of my shots have been outdoors with plenty of light anyway), and from what I've seen in the sample pics of the 24-105 and 70-200 even more so, it seems like you can still achieve that with f/4 on a longer lens. I'll give that one some thought though, thanks for the recommendation.


Still processing everyone's input, but will respond when I have a bit more time. It's kind of funny how my choice on this lens effects what I get for my next lens too. So many possible permutations!

[neuroanatomist]

At one time, the EF-S 17-55 f/2.8 IS USM was in this race, but I think I was scared off by the price vs. build quality (constantly read about dust issues), the (perhaps overly hopeful) thought that I will be upgrading to ff in the not to distant future, and the focal length range being slightly wide for most of my use.

The build quality is very good - it's a very sturdy lens (quality seems similar to my EF 100mm f/2.8<span style="color: red;"]L Macro IS USM lens, which though an L lens also has a plastic barrel). I think the dust issue is overblown - I haven't seen any problem, personally, and I think the relatively small number of people who do are very vocal about it. But as you say, any EF-S lens useless if all you have is a FF body. It certainly needs to be 'paired' with a longer lens, like a 70-200mm, 100-400mm, etc. I should note that while it's the lens that's on my camera most of the time, most of my shooting is of my family - around the house, etc., and the zoom range does very well there (I have an EF 85mm f/1.8 for indoor close-ups). I think what you're really paying for with the 17-55mm is the optical quality, which is excellent.

One of the major reasons I like the fast aperture is the subject/background separation (because most of my shots have been outdoors with plenty of light anyway), and from what I've seen in the sample pics of the 24-105 and 70-200 even more so, it seems like you can still achieve that with f/4 on a longer lens.

When you look at sample pics, be sure to pay attention to the camera used - the 1.6x FOVCF applies not only to angle of view, but also to depth of field. So if you really like the OOF blur in a sample pic at f/4 on a FF body (all of Bryan's sample pics with the 24-105mm are on FF cameras), keep in mind that will be like f/6.4 on your XSi in terms of depth of field.

It's kind of funny how my choice on this lens effects what I get for my next lens too.

So very true!