I get asked a lot of questions about shooting weddings, and a lot of them are about cameras and gear, which is understandable since there are so many choices and so many different opinions out there.
There have never been so many DSLR camera choices available as there are today. Even a few years ago, some DSLR cameras were much better suited than others for the task of shooting a wedding. These days, a competent photographer could easily shoot a wedding with pretty much any DSLR on the market.
That said, there are DSLR cameras that are better suited to weddings than others.
The Nikon D3s and Nikon D700 are the best DSLR cameras ever available for shooting weddings. Their insane image quality at high ISO settings allows the photographer a wide latitude of creativity options that just aren't possible with any other camera. Add to that their incredible image quality, the fact that they have the best auto focus system on the planet today, and are built to withstand a nuclear explosion, and you have a pair of really incredible DSLR's that are perfectly suited for the challenges of photographing a wedding.
What's that? The D3s and D700 are a little out of your price range?
No problem. The Nikon D300s or the Nikon D90 are excellent alternatives that are a little lighter on the pocket book. I'd have no problem shooting a wedding with a pair of Nikon D90 DSLR's, and at less than $1,000 per body, their probably the best value on the market today. The image quality from the Nikon D90 is exceptional, and the auto focus performance is VERY good.
So far I've only mentioned Nikon DSLR cameras. While I think Nikon makes the best DSLR cameras available today, and certainly offers the BEST warranty of any DSLR manufacturer, there are certainly some other great camera options out there outside of the Nikon line-up. Canon, Sony, and Pentax all have some excellent DSLR offerings for the wedding photographer.
Canon's 5D MkII is a full frame favourite among a lot of wedding photographers. It's high ISO abilities are very good... not in the same league as the Nikon D3s or D700, but still very good.
The new Canon 7D is also fast becoming a wedding photographer favourite for those who shoot Canon. A crop sensor DSLR, which at 18MP produces images which are a little noisy for my taste, the 7D features a new and improved Canon auto focus system.
I'd stay away from the Canon 50D if you're shopping. It produces images that are noisy by comparison and are not of a quality that is worthy of a Canon DSLR in my opinion. You're better off with the previous Canon 40D.
The Canon Rebel XSi is a pretty decent little performer if you are on a tight budget. Not a bad idea to buy 2 of these bodies and spend the rest of your money on high quality lenses if you can't afford the more expensive bodies and the better lenses. I'd steer clear of the Rebel T1i as it has a similar chip to the 50D so you get the same image quality issues as the 50D.
For those of you considering a Canon DSLR purchase, Canon quality control is not the best, so be careful to test your new Canon DSLR if you buy one to make sure it doesn't have auto focus problems, exhibit banding in the images, or have other functional problems. You can find numerous accounts of folks who have problems with Canon DSLR's if you search the net, and I really hope they address the problem soon.
Sony has quite a few options in the DSLR arena now and are obviously looking to establish themselves as a major player. If you're a Sony fan, consider the full frame A850 as an excellent pro featured DSLR at a bargain price. I personally don't know of any pros shooting weddings with Sony equipment, but I'm sure that will change as they continue to improve their offerings.
Pentax fans can have a look at the K7, a great value that is one of the most full featured DSLR cameras on the market today. For the price, it's a bargain. My only caveat to the Pentax system is that their auto focus isn't quite up to par with Nikon or Canon (when Canon auto focus works).
My #1 Recommendation for a Wedding Photographer's DSLR is the Nikon D3s. It's simply the best DSLR out there right now.
My #2 Recommendation for a Wedding Photographer's DSLR is the Nikon D700. Lighter and less expensive than the D3s, you still get 90% of the D3s goodness at almost half the price.
My #3 Recommendation for a Wedding Photographer's DSLR is the Nikon D90. To date, the Nikon D90 is the best value in a DSLR ever. If your budget doesn't allow for a D700 or a D3s, the D90 will do you just fine.
Unfortunately, Canon's quality control issues, auto focus problems, and shorter warranties, prevent me from recommending them in my top 3 recommendations. I feel that these problems just shouldn't exist in top quality equipment, and therefore I can't recommend them in good conscience.
Remember, if you're charging money to shoot weddings, you ABSOLUTELY have to have a back-up body. If you can't afford a D3s or D700 and a backup body, you NEED to be looking at two less expensive bodies like the D90 that fit in your budget.
Professional photographers ALWAYS need to have backup equipment. Don't even think about skimping here. You could be sued if you've been paid to shoot a wedding and you have an equipment failure and no backup. And rightly so. ALWAYS have backup equipment on hand.