I am planning on getting the following lenses. I just want to know if
I am making the right choice. Thanks
Sigma 10-20mm
Canon 24-105 f/4L IS USM
Canon 70-200 f/4L IS
Canon 100 f/2.8 macro
These lenses are going to sit on a 40d
For wildlife, you'll need at least 300mm. The 100-400mm IS zoom and 300mm and 400mm primes are all good choices.
For portraits on a cropped body, I'd go with a prime, since you'll want a shallow DOF. The 50 f/1.4 and 85 f/1.8 are both excellent choices, as they have an equivalent focal length of approx 85mm and 135mm, respectively, on a cropped body, which are the classic portraiture focal lengths.
For general-purpose outdoor use and some indoor use (in good lighting), the EF-S 17-55 f/2.8 IS can't be beat. I think you'll find the 24-105 f/4 to be far too slow indoors without a flash and not suitable for portraits. Also, it's a great walkaround lens on a FF body, but on a cropped body, the 24mm is not wide enough. You'll want to start your general-purpose zoom at 17mm or 18mm. Either that, or you'll be swapping the 10-22 and 24-105 a lot. Also, the f/2.8 on the 17-55 is very useful. It can even be used for portraits at the 55mm end.
For general-purpose indoor use, there is no zoom which is fast enough without a flash. You'll want f/2 or faster primes. The Sigma 30mm f/1.4, Canon 50mm f/1.4, Canon 85mm f/1.8, and Canon 100mm f/2 are all high quality lenses at relatively affordable pricing. You may also want to consider the newly-released Sigma 50mm f/1.4 over the Canon 50mm f/1.4. For many (including myself), the Sigma 30mm f/1.4 plus the Canon 85mm f/1.8 seems to cover most framing situations for indoor and otherwise low-light photography on a cropped body.
With that said, you may also consider the 70-200 f/2.8 IS for portrait and wildlife. However, adding a 1.4x TC will reduce your IQ slightly and won't stand up to the 100-400mm, 300mm, or 400mm for sharpness. But, it is a highly regarded lens in its own right and can safely be extended with the 1.4x TC without sacrificing too much IQ. The 2x TC is not recommended, as it degrades IQ too much.
If you want a good quality UAW, I'd swap in either the Canon EF-S 10-22 or the Tokina 11-16 for the Sigma 10-20. The Canon 10-22 is an excellent lens in nearly all aspects, though the Tokina beats it on sharpness. The Tokina is as sharp as the EF-S 17-55.
Finally, you may want to consider the Sigma 30mm f/1.4. On a cropped body, it has an effective focal length of approx. 50mm, which is the "standard" focal length (neither wide nor telephoto). It's also very sharp and attractively priced. In other words, it has a high IQ/price ratio.
As a disclaimer, I have:
Sigma 30mm f/1.4 (my main indoor lens)
Canon 50mm f/1.8 (I hardly ever use this now)
Canon 85mm f/1.8 (my main portrait lens)
Canon EF-S 17-55mm f/2.8 IS (may main outdoor lens)
Canon 70-200 f/4 IS
...and am very happy with this setup for walk-around photography, general family shots, portraits, and landscape (with 17mm from the EF-S). However, I can't get anywhere near close enough to the wildlife with the 200mm, so if/when I do wildlife shooting, I'll likely get a lens capable of at least 400mm from the lens itself.
