For my next trip, I'm planning to bring a new Canon Rebel XTi, which has a 1.6X magnification factor vs 35mm film cameras.

This presents a problem for selecting a wide angle lens. If I were bringing a film camera, I'd probably go for something like a 24mm prime lens. However, in the digital world, the equivalent lense would be 15mm because 24*(1/1.6)=15. When I look for lenses in this focal range online, the descriptions usually include "fisheye" and "vignetting," two things I don't want.

Are these descriptions only valid for 35mm film cameras and full-framed digital cameras, or will they still apply for a cropped camera?

If you have used the Rebel XT, 30D, or another camera with the same sensor, can you recommend a prime and/or zoom wide angle lens?

Sorry, but you have your calculation reversed. The 1.6 is a magnification factor, so for a 24mm lens, on the Rebel XTi, it would be equivalent to a 38.4mm lens, not a 15mm lens.

I use the Canon 17-40mm L zoom and it works quite well. It give me an equivalent 27.2-64mm lens. Not good for extreme wide angle shots, but good for general purpose wide angle work.

Mitch

djperry's focal length calculation is correct. He wants the equivalent FOV on his DSLR that a 24mm would give him on film... so he'll need a 15mm for the Rebel.

I've read good reviews of the Tokina 12-24mm and Sigma 10-20mm. You might want to check out one of those. I'm a Nikon user so I don't know if Canon has an equivalent lens. Both the Tokina and Sigma lenses are rectilinear.

Yeah, you're right, you'd want something around 15mm...
The Sigi and the Tokina mentioned above are both good choices, and Canon also makes a 10-22.
I have the Sigma and I am quite happy with it. It is pretty sharp. The Tokina is also supposed to be quite sharp, though it sounds like its a bit more susceptable to flair.
The Canon does have the widest range of the 3, but it is also more expensive, and arguably of a worse build quality, tho optical it rates quite highly.

The Sigma and Canon both look good to me, but the Canon is $200 more expensive. I guess I'll have to think about it some more. I don't want to break the bank for a wide angle lens, but I want something better than the kit lens that you can get with the camera. By the way, is f4 (the Sigma's max aperture) fast enough for most indoors conditions? I wouldn't think it would be very different compared to the Canon's f3.5, but maybe.

Tamron have recently bought out a 17-50mm f/2.8, so it's faster than the f4 if you're worried about speed for indoor shooting. I haven't used it, but from all reports it's pretty decent. It's selling in the UK for around £280, but I'm not sure how much it is in the US.

I'm tossing up between getting that, or getting Tamron's 28-75mm f/2.8, which is a bit cheaper at £200. It all comes down to that wide end......

Generally 4 is not fast enough for indoor shooting unless u have a tripod (always recommended) or are shooting at a very high ISO. but 3.5 wouldn't make much difference. That tamron 17-50 would be awesome on a full frame, but not wide enough for your needs on an APS-C sensor.

I'll I can say from my own experience is that I own the Sigma 10-20 and am quite happy with it.

I JUST made this choice myself. Today, in fact. And I settled with...the Canon. After reading way more reviews, info, opinions and mtf charts than I care to mention, I concluded that the Canon is simply the best lens available, with the Tokina in a very close second.

Check out this comparison:
http://www.kenrockwell.com/tech/digital-wide-zooms/comparison.htm

It may not seem like a big deal, but the extra 2mm on the Canon is a HUGE difference. WIth that said, the only reason I got the Canon is because I got a great deal on it ($550 used). If it wasn't for that, I would've gotten the Tokina because it is $200 cheaper and comes with a hood. THe Tokina is also built better but the Canon has better optics (on par with L lenses)

Also, I believe the Canon will hold its value better than third party lenses.

Good luck on your choice!

Yeah it sounds like you made a good choice. Honestly I think you did right by not getting the Tokina. I know people rate it quite highly, but it has two major faults:
first, that 2mm at the wide end makes a big difference, I think you would really miss it on the Tokina. Second, while great in terms of sharpness and lack of distortion, the Tokina seemed to have a lot of problems with flare. Flare is a real issue when shooting with a UWA lens, so why exasorbate that problem with a lens that has flare problems?
just my 2 cents.

Anyway, let me know how you like the Canon.

Too bad we all can't afford full frame cameras like the 5D. That way we could be shooting with the 16-35L and get crazy sharpness as well as a MUCH faster lens. Oh well, a man can dream...

Thanks for all the advice. That side-by-side comparison of the four lenses was very helpful. I ended up going with the Canon, used on ebay. It should get here soon, and I'm pretty sure I'll be happy with it, despite the higher pricetag.

Congrats on the Canon!
Mine should be here any day now.
In the meantime, i've also been looking at the Hoya Pro-1 Digital HMC UV filter and circular polarizer and a hood for it.
There's a guy on ebay selling the 77mm filters very cheaply...ebay ID is besteastern
he is based in hong kong but the peeps at dpreview.com say he is legit. might even spring for the B+W filters at his prices...